documentqp

TIME 1 hour

INSTRUCTIONS TO CANDIDATES

Write your name, Centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided on the question paper.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question.

You may lose marks if you do not show your working or if you do not use appropriate units.

This question paper consists of 11 printed pages and 1 blank page.MML 1439 4/01 S16048/2© CIE 2002 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONS

General Certificate of Education Advanced Level

CHEMISTRY 9701/4PAPER 4

MAY/JUNE SESSION 20021 hour

Candidates answer on the question paper.Additional materials:

Data Booklet

UNIVERSITY of CAMBRIDGELocal Examinations Syndicate

CandidateCentre Number Number

Candidate Name

FOR EXAMINER’S USE

1

2

3

4

5

6

7

TOTAL

http://www.xtremepapers.net

Answer all the questions in the spaces provided

1 (a) Write an expression for Kw.

.................................................................................................................................... [1]

(b) Use your expression to help you calculate the pH of 0.200 mol dm–3 NaOH(aq).

..........................................................................................................................................

.................................................................................................................................... [2]

(c) The pH of 0.200 mol dm–3 NH3(aq) is 11.3. Explain why this answer differs from youranswer in (b).

..........................................................................................................................................

.................................................................................................................................... [1]

(d) A 20.0 cm3 sample of 0.200 mol dm–3 NH3(aq) was titrated with 0.100 mol dm–3 HCl.On the following axes, sketch how the pH changes during this titration. Mark clearlywhere the end point occurs.

[3]

volume of added acid / cm3

pH

14

7

00 10 20 30 40 50 60

2

9701/4/S02

ForExaminer's

Use

(e) From the following list of indicators, put a tick in the box by the side of the indicator youconsider most suitable for this titration.

[1]

(f) A solution containing NH3(aq) and NH4Cl(aq) acts as a buffer solution, resistingchanges in pH when acids or alkalis are added.

Explain with the help of equations how this mixture acts as a buffer.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 10]

3

9701/4/S02 [Turn over

ForExaminer's

Use

indicatorpH at which colour

changesplace one tick only

in this column

methyl violet

methyl orange

bromothymol blue

phenolphthalein

0.0 - 1.6

3.1 - 4.4

6.0 - 7.6

8.3 - 10.0

2 The ester 4-nitrophenyl ethanoate hydrolyses in alkaline solution according to the following equation.

(a) Suggest, and briefly describe, a suitable experimental technique for studying the rateof this reaction.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [4]

(b) The reaction rate was studied using two solutions of different hydroxide ionconcentrations.

run A: [OH–] = 0.20 mol dm–3

run B: [OH–] = 0.40 mol dm–3

The following graphs show how the concentration of the ester, 4-nitrophenyl ethanoate,varied over time in the two runs.

0.001

0.0009

0.0008

0.0007

0.0006

0.0005

0.0004

0.0003

0.0002

0.0001

00 10 20 30 40 50 60

run A

run B

time /min

[est

er]/

mol

dm

–3

CH3–C–O–

O O

–NO2 + 20H– CH3–C–O– + –O– NO2 + H2O

colourless yellow

4

9701/4/S02

ForExaminer's

Use

(i) By drawing tangents on the graphs, measure and calculate the initial rates ofreaction during the two runs. Give the units in each case.

initial rate of run A ....................................................................................................

initial rate of run B ....................................................................................................[3]

(ii) By using your results, calculate the overall order of reaction with respect to [OH–].

............................................................................................................................ [1]

(iii) From the curve of run B, determine the order of reaction with respect to [ester].

............................................................................................................................ [1]

(iv) Explain how you arrived at you answer in (iii).

..................................................................................................................................

............................................................................................................................ [1]

(v) Write a rate equation for the reaction.

............................................................................................................................ [1]

(vi) Use your rate equation and the initial rates to calculate a value for the rateconstant, including units.

..................................................................................................................................

............................................................................................................................ [2]

[Total: 13]

5


ForExaminer's

Use

3 (a) Write an equation to represent the thermal decomposition of calcium nitrate, Ca(NO3)2.

.................................................................................................................................... [1]

(b) Describe and explain how the thermal stabilities of the Group II nitrates vary down thegroup.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [3]

(c) When a molten nitrate of a Group I metal is heated strongly, it evolves oxygen andleaves the metal nitrite, MNO2 (M = Na, K, Rb or Cs).

(i) Write a balanced equation for this reaction.

..................................................................................................................................

(ii) When a particular Group I metal nitrate was heated in this way until no furtherchange occurred, it lost 10.85% of its mass. Calculate the Ar of the metal andhence identify it.

[3]

[Total: 7]

6

9701/4/S02

ForExaminer's

Use

4 (a) Complete the electronic configuration of the Fe3+ ion.

1s2 2s2 2p6 3s2 3p6 .................................................................................................... [1]

(b) By quoting suitable data from the Data Booklet, explain how E o– values can be used toshow the relative oxidising abilities of

(i) the halogens Cl2, Br2, I2,

..................................................................................................................................

..................................................................................................................................

(ii) the transition metal ions Cr3+, Fe3+, Co3+.

..................................................................................................................................

..................................................................................................................................[3]

(c) Use these E o– values to predict whether a reaction will occur when the following pairsof aqueous solutions are mixed. If a reaction occurs, write a balanced equation andcalculate the E o–cell.

(i) Fe3+(aq) and Cl –(aq)

..................................................................................................................................

..................................................................................................................................

(ii) Co3+(aq) and Br–(aq)

..................................................................................................................................

..................................................................................................................................

(iii) Cr2+(aq) and I2(aq)

..................................................................................................................................

..................................................................................................................................[4]

[Total: 8]

7


ForExaminer's

Use

5 The common analgesic drug paracetamol has the following structure.

(a) Name the two functional groups in the paracetamol molecule

.............................................................. and ........................................................... [2]

(b) Draw the structural formulae of the molecules or ions formed when paracetamol reactswith

(i) Br2(aq),

(ii) NaOH(aq) in the cold,

(iii) NaOH(aq) under reflux.

[3]

(c) Paracetamol can be synthesised by reacting 4-aminophenol with compound X.

(i) Suggest a possible identity of X.

..................................................................................................................................

(ii) What reagent would you use to convert ethanoic acid, CH3CO2H, into X?

..................................................................................................................................[2]

[Total: 7]

OH + XH2N paracetamol

CH3CONH OH

8

9701/4/S02

ForExaminer's

Use

6 Methylbenzene can react with chlorine in two ways, depending on the conditions of thereaction.

(a) State the condition needed for

(i) reaction I,

..................................................................................................................................

(ii) reaction II.

..................................................................................................................................[2]

(b) One of the two compounds A and B reacts with NaOH(aq), but the other is inert.

(i) Which one (A or B) does not react? Give a reason for your answer.

..................................................................................................................................

..................................................................................................................................

(ii) Write an equation for the reaction with NaOH(aq) that does occur.

[2]

[Total: 4]

CH3

Clreaction I

CH3

reaction II

Cl2 Cl2

CH2Cl

A B

9


ForExaminer's

Use

7 Phenylamine is an important intermediate compound for the production of dyes.

phenylamine

(a) Phenylamine can be synthesised from benzene in two steps. Draw the structural formulaof the intermediate Y in the scheme below, and suggest reagents and conditions forsteps I and II.

reagent + conditions for step I .........................................................................................

reagent + conditions for step II ........................................................................................[4]

(b) Phenylamine is a weak base.

(i) Write an equation showing phenylamine acting as a base.

(ii) How would you expect its basicity to compare with that of ammonia?

..................................................................................................................................

(iii) Explain the reasoning for your answer in (ii).

..................................................................................................................................

..................................................................................................................................[3]

I

Y

II—NH2

NH2

10

9701/4/S02

ForExaminer's

Use

(c) Dyes can be made from phenylamine by first converting it into benzenediazoniumchloride, and then coupling this with a phenol.

(i) State the reagents and condition needed for step III.

..................................................................................................................................

(ii) What reagent is the phenol dissolved in for step IV to be effective?

..................................................................................................................................

(iii) Suggest the structural formula of the dye formed when benzenediazoniumchloride is coupled with 2-methylphenol.

[4]

[Total: 11]

NH2 N2+Cl –

III IVdye

+ a phenol

11

9701/4/S02

ForExaminer's

Use

BLANK PAGE

12

9701/4/S02

This document consists of 12 printed pages.

SP (NF/KN) S33030/4© CIE 2003 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education

Advanced Subsidiary Level and Advanced Level

CHEMISTRY 9701/04

Paper 4 Structured QuestionsMay/June 2003

1 hourCandidates answer on the Question Paper.Additional Materials:

Data Booklet

READ THESE INSTRUCTIONS FIRST

Write your name, Centre number and candidate number in the spaces provided at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.

Centre Number Candidate Number Name

For Examiner’s Use

If you have been given a label, look at thedetails. If any details are incorrect ormissing, please fill in your correct detailsin the space given at the top of this page.

Stick your personal label here, ifprovided.

1

2

3

4

5

6

TOTAL

www.xtremepapers.net


2

9701/04/M/J/03

Answer all the questions in the spaces provided.

1 (a) What do you understand by the term standard electrode potential?

..........................................................................................................................................

......................................................................................................................................[2]

(b) The following cell was set up between a copper electrode and an unknown metalelectrode M2+(aq) / M(s). The standard cell potential was found to be 0.76 V, and thecopper foil was the positive electrode.

(i) Use the Data Booklet to calculate the standard electrode potential of theM 2+(aq) / M(s) system.

...................................................................................................................................

(ii) Draw an arrow over the voltmeter symbol in the above diagram to show thedirection of electron flow through the voltmeter.

(iii) Predict the outcomes of the following situations. Describe what you might see andwrite ionic equations for any reactions that occur.

I A rod of metal M is dipped into a solution of 1 mol dm–3 CuSO4.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

ForExaminer’s

Use

V

copper foil

CuSO4(1 mol dm–3)

unknown metalwire, M

M 2+(1 mol dm–3)

direction of electron flow



3

9701/04/M/J/03 [Turn over

II Dilute sulphuric acid is added to a beaker containing a powdered sample of metalM.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[6]

(c) Because of its increased scarcity, cheaper copper ornaments are no longer made fromthe solid metal, but from iron that has been copper plated.

(i) Complete the following diagram showing the set-up for a copper electroplatingprocess. Show clearly the polarity (+/–) of the power source, and suggest a suitableelectrolyte.

(ii) A current of 0.500 A is passed through the electroplating cell. Calculate the timerequired to deposit a mass of 0.500 g of copper on to the ornament.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[5]

[Total : 13]

ForExaminer’s

Use

A

d.c. source

electrolyte:

object to be plated



4

9701/04/M/J/03

2 (a) Barium ions are poisonous. Patients with digestive tract problems are sometimes givenan X-ray after they have swallowed a ‘barium meal’, consisting of a suspension ofBaSO4 in water. The [Ba2+(aq)] in a saturated solution of BaSO4 is too low to causeproblems of toxicity.

(i) Write an expression for the solubility product, Ksp, for BaSO4, including its units.

...................................................................................................................................

(ii) The numerical value of Ksp is 1.30 × 10–10. Calculate [Ba2+(aq)] in a saturatedsolution of BaSO4.

...................................................................................................................................

...................................................................................................................................

(iii) The numerical value of Ksp for BaCO3 (5 × 10–10) is not significantly higher thanthat for BaSO4, but barium carbonate is very poisonous if ingested. Suggest areason why this might be so.

...................................................................................................................................

...................................................................................................................................[3]

(b) A useful commercial source of magnesium is sea water, where [Mg2+(aq)] is0.054 mol dm–3. The magnesium is precipitated from solution by adding calciumhydroxide.

Mg2+(aq) + Ca(OH)2(s) → Ca2+(aq) + Mg(OH)2(s)

(i) Write an expression for the Ksp of Mg(OH)2, including its units.

...................................................................................................................................

(ii) The numerical value for Ksp is 2.00 x 10–11. Calculate [Mg2+(aq)] in a saturatedsolution of Mg(OH)2.

...................................................................................................................................

...................................................................................................................................

ForExaminer’s

Use



5


(iii) Hence calculate the maximum percentage of the original magnesium in theseawater that this method can extract.

...................................................................................................................................

...................................................................................................................................[5]

(c) The magnesium ions in seawater are mainly associated with chloride ions.

(i) Use the following ∆H o__

f values to calculate a value for the ∆H o__ of the followingreaction.

MgCl2(s) → Mg2+(aq) + 2Cl–(aq)

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Use your answer to explain why MgCl2 is very soluble in water.

...................................................................................................................................[2]

(d) All the chlorides of Group II elements are soluble in water. The same is not true of theirsulphates. These become less soluble as the group is descended.

Explain qualitatively the variation in solubility of the sulphates of the elements inGroup II down the Group from magnesium to barium.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

[Total : 12]

ForExaminer’s

Use

species ∆H o__f /kJ mol–1

MgCl2 (s) –641

Mg2+(aq) –467

Cl – (aq) –167



6

9701/04/M/J/03

3 (a) The melting points of some oxides of Group IV elements are given below.

Describe the bonding in each oxide, and how it relates to its melting point.

(i) CO2

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) SiO2

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iii) SnO2

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

ForExaminer’s

Use

oxide meltingpoint / oC

CO2 –78

SiO2 1610

SnO2 1630



7


(b) Writing balanced equations where appropriate, describe how the above three oxidesdiffer in their reactions with

(i) NaOH(aq),

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) HCl(aq).

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[4]

(c) The last oxide in Group IV, PbO2, reacts with concentrated hydrochloric acid liberatingchlorine gas.

Use the Data Booklet to calculate the E o__

cell and to write a balanced equation for thisreaction.

..........................................................................................................................................

......................................................................................................................................[2]

[Total : 9]

ForExaminer’s

Use



8

9701/04/M/J/03

4 Chloroacetophenone (compound D, below) was formerly the most widely used tear gas,under the codename CN. It was used in warfare and in riot control. It can be synthesisedfrom ethylbenzene, A, by the following route.

(a) Suggest reagents and conditions for step I.

......................................................................................................................................[1]

(b) Suggest reagents and conditions for converting ethylbenzene into compound E, anisomer of B.

......................................................................................................................................[1]

(c) Draw the structure of the product obtained by heating ethylbenzene with KMnO4.

[1]

(d) Describe a test (reagents and observations) that would distinguish compound C fromcompound F.

reagents

..........................................................................................................................................

observation with C

..........................................................................................................................................

observation with F

..........................................................................................................................................[2]

COCH2CH3

F

CH2CH3Cl

E

ForExaminer’s

Use

CH2CH3 CHClCH3 CH(OH)CH3 COCH3 COCH2ClI II III IV

A B C D



9


(e) The efficiency of a tear gas is expressed by its ‘intolerable concentration’, I.C. The I.C.of the tear gas CN has been measured as 0.030 g m–3 of air.How many moles of chloroacetophenone need to be sprayed into a room of volume60 m3 in order to achieve this concentration?

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(f) Residues of CN can be destroyed by hydrolysis with an aqueous alkali.

Compounds G and H are isomers of compound D.

(i) Arrange the three isomers D, G and H in order of increasing ease of hydrolysis.

...................................................................................................................................

(ii) Explain the reasoning behind your choice.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

[Total : 10]

CH2COCl Cl COCH3

G H

COCH2Cl + OH– COCH2OH + Cl–

D

ForExaminer’s

Use



10

9701/04/M/J/03

5 (a) Acyl chlorides are useful intermediates for making various acid derivatives. Thefollowing reaction scheme shows some of the reactions of ethanoyl chloride.

(i) Suggest a reagent for step I.

...................................................................................................................................

(ii) Write an equation showing the reaction between phenol and NaOH(aq), thereagents in step II.

...................................................................................................................................

(iii) Draw the structural formulae of products J and K in the boxes above.[4]

CH3CO2H CH3COClOH + NaOH(aq)

J

K

step I

step II

step III NH3

ForExaminer’s

Use



11


(b) The diacid L occurs naturally and is used as a food additive to enhance the acidicflavour in some fruit drinks.

HO2CCH2CH2CO2HL

When the diacyl chloride of L is reacted with HOCH2CH2OH, a polymer is formed.

(i) What type of polymerisation is occurring here?

...................................................................................................................................

(ii) Write an equation showing the reaction between one mole of the diacyl chloride ofL and two moles of HOCH2CH2OH.

[3]

(c) The following formula represents a section of another polymer.

(i) What type of polymer is this?

...................................................................................................................................

(ii) Draw the structural formula of each of the monomers that make up this polymer.

[3]

[Total : 10]

CONHCH2CH2CH2CH2NHCO

ForExaminer’s

Use



12

9701/04/M/J/03

6 (a) Titanium is an important transition metal. The metal itself is a component of many high-strength low-weight alloys, and its oxide is used as an opaque agent in many paints and pigments.

(i) Write out the electronic configuration of the titanium atom.

...................................................................................................................................

(ii) Titanium forms two chlorides. Suggest possible formulae for them.

...................................................................................................................................[2]

(b) Anhydrous copper sulphate, CuSO4(s), is a white powder that readily dissolves in water.

(i) Describe and explain what is seen when CuSO4(s) is stirred with water.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Describe and explain the final colour change seen when an excess of NH3(aq) isadded to CuSO4(aq).

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[4]

[Total : 6]

ForExaminer’s

Use



This document consists of 11 printed pages and 1 blank page.

SP (NF/GR) S60728/4© UCLES 2004 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education


CHEMISTRY 9701/04

Paper 4 Structured QuestionsMay/June 2004

1 hour 15 minutesCandidates answer on the Question Paper.Additional Materials: Data Booklet


Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.You may use a calculator.





1

2

3

4

5

6

Total



2

9701/04/M/J/04


1 Magnesium is used extensively in the form of alloys as a constructional material due to itslow density (1.7 g cm–3, compared to 7.8 g cm–3 for iron). It is usually prepared by theelectrolysis of magnesium chloride, MgCl2, at a temperature a little above its melting point of715 °C.

(a) Suggest the half-equation that represents the production of magnesium at the cathodeduring the electrolysis.

......................................................................................................................................[1]

(b) What will be the product at the other electrode?

......................................................................................................................................[1]

(c) Suggest two properties of its atoms that could explain why magnesium is less densethan iron.

..........................................................................................................................................

......................................................................................................................................[2]

One of the reasons the melting point of magnesium chloride is quite high is because it has afairly high lattice energy.

(d) (i) Explain the term lattice energy.

...................................................................................................................................

...................................................................................................................................

(ii) Write a balanced equation including state symbols to represent the lattice energyof magnesium chloride.

...................................................................................................................................

...............................................................................................................................[4]

(e) Suggest, with an explanation in each case, how the lattice energy of magnesiumchloride might compare with that of

(i) sodium chloride, NaCl,

...................................................................................................................................

...................................................................................................................................

(ii) calcium chloride, CaCl2.

...................................................................................................................................

...............................................................................................................................[4]

ForExaminer’s

Use

© UCLES 2004



3


(f) Use the following data to calculate a value for the lattice energy of sodium chloride.

∆Hf (NaCl) = –411 kJ mol–1

∆Hat (Na) = 107 kJ mol–1

∆Hat (Cl) = 122 kJ mol–1

first ionisation energy of Na = 494 kJ mol–1

electron affinity of Cl = –349 kJ mol–1

lattice energy of NaCl = ........................................ kJ mol–1 [3]

[Total: 15]

ForExaminer’s

Use

© UCLES 2004



4

9701/04/M/J/04

2 All the Group IV elements form chlorides with the formula MCl4.

(a) Describe the bonding in, and the shape of, these chlorides.

(i) bonding .....................................................................................................................

(ii) shape ....................................................................................................................[2]

The boiling point of lead(IV) chloride cannot be measured directly because it decomposeson heating. The following table lists the boiling points of three Group IV chlorides.

(b) (i) Plot these data on the following axes and extrapolate your graph to predict what theboiling point of PbCl4 would be if it did not decompose.

(ii) Suggest why the boiling points vary in this way.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[4]

Si Ge Sn Pb50°C

100°C

150°C

ForExaminer’s

Use

© UCLES 2004

chloride b.p. / °C

SiCl4 58

GeCl4 83

SnCl4 114



5


(c) SiCl4 reacts vigorously with water whereas CCl4 is inert.

(i) Suggest a reason for this difference in reactivity.

...................................................................................................................................

(ii) Write an equation for the reaction between SiCl4 and water.

...................................................................................................................................

(iii) Suggest, with a reason, whether you would expect GeCl4 to react with water.

...................................................................................................................................

...................................................................................................................................[3]

(d) SiCl4 is used to make high-purity silicon for the semiconductor industry. After it hasbeen purified by several fractional distillations, it is reduced to silicon by heating withpure zinc.

(i) Suggest an equation for the reduction of SiCl4 by zinc.

...................................................................................................................................

(ii) Use your equation to calculate what mass of zinc is needed to produce 250 g ofpure silicon by this method.

mass of zinc = ....................... g [3]

[Total: 12]

ForExaminer’s

Use

© UCLES 2004



6

9701/04/M/J/04

3 By using iron and its compounds as examples, outline the different modes of action ofhomogeneous and heterogeneous catalysis.Choose two examples, and for each example you should• state what the catalyst is, and whether it is acting as a homogeneous or a

heterogeneous catalyst,• write a balanced equation for the reaction.

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..............................................................................................................................................[8]

[Total: 8]

ForExaminer’s

Use

© UCLES 2004



7


4 This question is about the reactions of some functional groups.

(a) (i) Draw the structural formula of an amide of your choice containing four carbonatoms.

(ii) What reagents and conditions are needed to hydrolyse this amide?

...................................................................................................................................

(iii) Write a balanced equation showing the hydrolysis of the amide whose structuralformula you drew in part (i).

...............................................................................................................................[4]

(b) (i) Draw the structural formula of an acyl chloride containing three carbon atoms.

(ii) What starting material and reagent are needed to form this acyl chloride?

...................................................................................................................................

(iii) Write a balanced equation showing the formation of an ester containing five carbonatoms from the acyl chloride you drew in part (i).

...............................................................................................................................[3]

[Total: 7]

ForExaminer’s

Use

© UCLES 2004



8

9701/04/M/J/04

5 (a) State the reagents and conditions needed to convert benzene into

(i) chlorobenzene,

...................................................................................................................................

(ii) bromobenzene,

...................................................................................................................................

(iii) nitrobenzene.

...................................................................................................................................[4]

(b) The nitration of benzene is a two-step reaction that can be represented as follows.

(i) Identify the cation A+. ...............................................................................................

(ii) Draw the structure of the intermediate B in the box. [2]

+ A+ NO2 + H+

B

ForExaminer’s

Use

© UCLES 2004



9


(c) The position of substitution during the electrophilic substitution of arenes is determinedby the nature of the group already attached to the ring.

Electron-withdrawing groups such as –CO2H or –NO2 direct the incoming group to the3-position.

On the other hand, electron-donating groups such as –CH3 or –NH2 direct the incominggroup to the 2- or 4- positions.

Use this information to suggest a likely structure for the organic product of each of thefollowing reactions.

(i)

(ii)

[2]

[Total: 8]

NH2

CO2H

chlorination

NO2

bromination

CH3 CH3

Br

CH3

Brbromination +

CO2H CO2H

NO2

nitration

ForExaminer’s

Use

© UCLES 2004



10

9701/04/M/J/04

6 Much research has been carried out in recent years investigating the exact structure of silk.The silk of a spider’s web is at least five times as strong as steel, and twice as elastic asnylon. A silk fibre is composed of many identical protein chains, which are mainly made fromthe amino acids glycine, alanine and serine, with smaller amounts of four other amino acids.

NH2–CH2–CO2H NH2–CH–CO2H NH2–CH–CO2H| |CH3 CH2OH

glycine alanine serine

(a) Amino acids can exist as zwitterions. Draw the zwitterionic structure for glycine.

[1]

(b) Amino acids can act as acids or bases. Write equations to show:

(i) the reaction between alanine and HCl(aq),

...................................................................................................................................

(ii) the reaction between serine and NaOH(aq).

...................................................................................................................................[2]

(c) Draw the structural formula of a portion of the silk protein, showing three amino acidresidues. Label a peptide bond on your structure.

[3]

(d) What type of polymer is silk protein?

......................................................................................................................................[1]

ForExaminer’s

Use

© UCLES 2004



11

9701/04/M/J/04

(e) The Mr of a silk protein molecule is about 600,000. Assuming it is made from equalamounts of the above three amino acids, calculate the average number of amino acidresidues in the protein chain. [Mr (glycine) = 75; Mr (alanine) = 89; Mr (serine) = 105]

number of residues = ................................... [3]

[Total: 10]

ForExaminer’s

Use

© UCLES 2004



12

9701/04/M/J/04

BLANK PAGE

University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department ofthe University of Cambridge.




SPA (MML 8078 3/04) S77899/2© UCLES 2005 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education


CHEMISTRY 9701/04

Paper 4 Structured Questions A2 CoreMay/June 2005



Write your name, Centre number and candidate number in the spaces at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.





5

4

3

2

1

6

TOTAL




1 A student decided to determine the value of the Faraday constant by an electrolysisexperiment. The following incomplete diagram shows the apparatus that was used.

(a) (i) Apart from connecting wires, what two additional pieces of equipment are neededfor this experiment?

..................................................................................................................................

..................................................................................................................................

(ii) Complete the diagram, showing additional equipment connected in the circuit, andshowing the powerpack connected to the correct electrodes.

(iii) List the measurements the student would need to make in order to use the resultsto calculate a value for the Faraday constant.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[7]

(b) (i) Using an equation, state the relationship between the Faraday constant, F, theAvogadro constant, L, and the charge on the electron, e.

..................................................................................................................................

(ii) The value the student obtained was: 1 Faraday = 9.63 × 104 Coulombs

Use this value and your equation in (b)(i) to calculate the Avogadro constant (takethe charge on the electron to be 1.60 × 10–19 Coulombs)

..................................................................................................................................

..................................................................................................................................[2]

[Total: 9]

hydrogen being collected

power pack

inert electrodes

–

+

dilute H2SO4

2 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



2 (a) What do you understand by the term order of reaction?

.................................................................................................................................... [1]

(b) Cyanohydrins can be made by reacting ketones with an acidified solution of sodiumcyanide.

(CH3)2C=O + H+ + CN– → (CH3)2C(OH)CN

In a series of experiments, the reaction was carried out with different concentrations ofthe three reagents, and the following relative initial rates were obtained.

(i) Use the data in the table to deduce the order of the reaction with respect to

propanone ....................................................

hydrogen ions ..............................................

cyanide ions .................................................

(ii) Hence write a rate equation for this reaction.

..................................................................................................................................

Two different mechanisms have been suggested for this reaction

Mechanism A: (CH3)2C=O + H+ → (CH3)2COH+

(CH3)2COH+ + CN– → (CH3)2C(OH)CN

Mechanism B: (CH3)2C=O + CN– → (CH3)2C(O–)CN(CH3)2C(O–)CN + H+ → (CH3)2C(OH)CN

(iii) Which mechanism is consistent with the rate equation you deduced in (ii), andwhich step in this mechanism is the slower (rate determining) step? Explain youranswer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[7]

[Total: 8]

3

[Turn over

ForExaminer's

Use

9701/04/M/J/05© UCLES 2005

experimentnumber

[(CH3)2CO]/ mol dm–3

[H+]/ mol dm–3

[CN–]/ mol dm–3

1 0.020 0.060 0.060

2 0.020 0.050 0.050

3 0.020 0.050 0.060

4 0.025 0.050 0.050

relative initial rate /mol dm–3 sec–1

1.00

0.833

1.00

1.042



3 Limestone is an important raw material, used in building, steel making and agriculture.

The first stage in using limestone is often to heat it in a kiln.

CaCO3(s) → CaO(s) + CO2(g) �H = +178 kJ mol–1 reaction 1

Water is then added to the ‘quicklime’ produced in the kiln, to make ‘slaked lime’.

CaO(s) + H2O(l) → Ca(OH)2(s) �H = –82 kJ mol–1 reaction 2

(a) (i) Suggest two reasons why reaction 1 needs heating to a high temperature.

..................................................................................................................................

..................................................................................................................................

(ii) Explain whether MgCO3 would require a higher or a lower temperature thanCaCO3 for its decomposition.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[5]

Before the widespread use of cement, bricks and stones used for buildings were bondedtogether with a mixture of slaked lime, sand and water, known as lime mortar. On exposureto the air, the lime mortar gradually set hard due to the following reaction.

Ca(OH)2(s) + CO2(g) → CaCO3(s) + H2O(l)

(b) Use the data given above to calculate the enthalpy change for this reaction.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [1]

4 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



(c) One of the major ores of magnesium is the mixed carbonate called dolomite,CaMg(CO3)2.

Calculate the percentage loss in mass that would be observed when a sample ofdolomite is heated at a high temperature until the reaction had finished.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

[Total: 8]

5

[Turn over

ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



4 (a) (i) State the electronic configuration of the iron atom.

..................................................................................................................................

(ii) Apart from its electronic structure, state two properties of iron or its compoundsthat are characteristic of a transition element.

..................................................................................................................................

..................................................................................................................................[3]

(b) Acidified solutions of iron(II) salts can be titrated using a dilute solution of potassiummanganate(VII), KMnO4.

(i) Use the Data Booklet to calculate the standard cell potential and to write abalanced ionic equation for the reaction that takes place during the titration.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Explain why no indicator is required for this titration. What colour change wouldyou see at the end point?

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

(c) Use the reaction between Fe3+ ions and water molecules to explain the meanings ofthe terms ligand and complex formation.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

6 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



(d) An important biological molecule containing iron is haemoglobin.

(i) What is the role of haemoglobin in the body?

..................................................................................................................................

(ii) Use your answer to (i) to explain why carbon monoxide is poisonous.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[2]

(e) In a possible industrial synthesis of ethanol, the complex Fe(CO)5 catalyses thereaction between carbon monoxide, hydrogen and methanol according to the followingequation.

200 °CCH3OH + 2CO + H2 –––––→ CH3CH2OH + CO2300 atm

Describe a test (reagents and observations) that would distinguish ethanol frommethanol.

reagents ...........................................................................................................................

observation with methanol ...............................................................................................

observation with ethanol ............................................................................................. [2]

[Total: 13]

7

[Turn over

ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



5 (a) Give an expression for Ka as applied to the weak acid RCO2H.

..........................................................................................................................................

.................................................................................................................................... [1]

(b) The Ka values for three carboxylic acids are listed in the table below.

(i) Describe and explain the trend in acid strength illustrated by these values.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Calculate the pH of a 0.100 mol dm–3 solution of ClCH2CO2H.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Calculate the pKa value for Cl2CHCO2H.

..................................................................................................................................

..................................................................................................................................[5]

8 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005

acid Ka / mol dm–3

CH3CO2H 1.8 × 10–5

ClCH2CO2H 1.4 × 10–3

Cl2CHCO2H 5.5 × 10–2



(c) The acid ClCH2CO2H features in the industrial synthesis of the important weedkiller2,4-D.

(i) Suggest a possible reagent for reaction I.

..................................................................................................................................

(ii) What type of reaction is

reaction I, .................................................................................................................

reaction II? ...............................................................................................................

(iii) Describe a test (reagents and observations) that would distinguish phenol fromcompound A.

reagents ...................................................................................................................

observation with phenol ...........................................................................................

observation with compound A ..................................................................................

[5]

[Total: 11]

CH2OH

compound A

OH OH

Cl

Cl

OCH2CO2H

Cl

Clphenol

+ NaOH+ ClCH2CO2H

I II

2,4-D

9

[Turn over

ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



6 The antipyretic (fever-reducing) drug antifebrin can be made from benzene and ethanoicacid by the following route.

(a) (i) What type of reaction is reaction I?

..................................................................................................................................

(ii) Suggest the reagents and conditions for reaction I.

..................................................................................................................................

(iii) Complete the following scheme showing the mechanism of reaction I, by drawingappropriate formulae in the three boxes.

[6]

(b) (i) What type of reaction is reaction II?

..................................................................................................................................

(ii) Suggest the reagents and conditions for reaction II.

..................................................................................................................................[2]

NO2

+ +

NO2 NH2

NHCOCH3

I

CH3CO2H CH3COCl antifebrinIII

IV

II

10 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



(c) Suggest the reagents and conditions for reaction III.

.................................................................................................................................... [1]

(d) (i) Apart from the benzene ring, name the functional group in antifebrin.

..................................................................................................................................

(ii) What reagents and conditions are needed to hydrolyse antifebrin?

..................................................................................................................................[2]

[Total: 11]

11 ForExaminer's

Use

9701/04/M/J/05© UCLES 2005



BLANK PAGE

12

9701/04/M/J/05

Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Everyreasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, thepublisher will be pleased to make amends at the earliest possible opportunity.

University of Cambridge International Examinations is part of the University of Cambridge Local Examinations Syndicate (UCLES), which is itself a departmentof the University of Cambridge.




SPA SJF3704 T12878/2© UCLES 2006 [Turn over



CHEMISTRY 9701/04

Paper 4 Structured Questions A2 CoreMay/June 2006



Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.



1

2

3

4

5

Total



2

9701/04/M/J/06


1 The oxidation of nitrogen monoxide occurs readily according to the following equation.

NO(g) + �� O2(g) ⎯→ NO2(g)

The following table shows how the initial rate of this reaction depends on the concentrationsof the two reactants.

(a) (i) Use the data to determine the order of reaction with respect to each of thereagents.

order with respect to NO …………………………

order with respect to O2 …………………………

(ii) Write the rate equation for the reaction, and use it to calculate a value for the rateconstant, k, stating its units.

rate equation .............................................................................................................

numerical value of k = …………………………

units of k …………………………

(iii) Use your rate equation in (ii) to calculate the rate of reaction when [NO] = [O2] = 0.0025 mol dm–3.

rate of reaction =…………………………[6]

ForExaminer’s

Use

© UCLES 2006

[NO]/ mol dm–3

0.0050

0.0050

0.010

[O2]/ mol dm–3

0.0050

0.0075

0.0075

initial rate/ mol dm–3 s–1

0.02

0.03

0.12



3


(b) Nitrogen monoxide plays an important catalytic role in the oxidation of atmospheric SO2in the formation of acid rain.

(i) State the type of catalysis shown in this process.

...................................................................................................................................

(ii) Explain the steps involved in this process by writing equations for the reactions thatoccur.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

[Total: 9]

ForExaminer’s

Use

© UCLES 2006



4

9701/04/M/J/06

2 Monuments made of marble or limestone, such as the Taj Mahal in India and the Mayantemples in Mexico, are suffering erosion by acid rain. The carbonate stone is converted bythe acid rain into the relatively more soluble sulphate.

CaCO3(s) + H2SO4(aq) → CaSO4(s) + H2O(l) + CO2(g)acid rain

(a) (i) Write an expression for the solubility product, Ksp, of CaSO4, stating its units.

...................................................................................................................................

(ii) The Ksp of CaSO4 has a numerical value of 3 x 10–5. Use your expression in (i) tocalculate [CaSO4] in a saturated solution.

...................................................................................................................................

(iii) Hence calculate the maximum loss in mass of a small statue if 100 dm3 of acid rainfalls on it. Assume the statue is made of pure calcium carbonate, and that the acidrain becomes saturated with CaSO4.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[5]

(b) The life of such monuments is now being extended by treating them with a mixture ofurea and barium hydroxide solutions. After soaking into the pores of the carbonate rock,the urea gradually decomposes to ammonia and carbon dioxide. The carbon dioxidethen reacts with the barium hydroxide to form barium carbonate.

(NH2)2CO(aq) + H2O(l) ⎯→ 2NH3(g) + CO2(g)

Ba(OH)2(aq) + CO2(g) ⎯→ BaCO3(s) + H2O(l)

Acid rain then converts the barium carbonate to its sulphate.

BaCO3(s) + H2SO4(aq) ⎯→ BaSO4(s) + H2O(l) + CO2(g)

Barium sulphate is much less soluble than calcium sulphate. A saturated solutioncontains [Ba2+] = 9.0 x 10–6 mol dm–3.

(i) Explain why barium sulphate is less soluble than calcium sulphate.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

ForExaminer’s

Use

© UCLES 2006



5


(ii) Write an expression for the Ksp of barium sulphate and use the data to calculate itsvalue.

...................................................................................................................................

...................................................................................................................................[4]

(c) (i) Explain what is meant by the term lattice energy.

...................................................................................................................................

...................................................................................................................................

(ii) Predict, with a reason, how the lattice energy of BaSO4 might compare with that ofMgSO4.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

[Total: 12]

ForExaminer’s

Use

© UCLES 2006



6

9701/04/M/J/06

3 (a) A transition element X has the electronic configuration [Ar] 4s2 3d3.

(i) Predict its likely oxidation states.

...................................................................................................................................

(ii) State the electronic configuration of the ion X3+.

...................................................................................................................................[2]

(b) Potassium manganate(VII), KMnO4, is a useful oxidising agent in titrimetric analysis.

(i) Describe how you could use a 0.0200 mol dm–3 solution of KMnO4 to determineaccurately the [Fe2+] in a solution. Include in your description how you wouldrecognise the end-point in the titration, and write an equation for the titrationreaction.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) A 2.00 g sample of iron ore was dissolved in dilute H2SO4 and all the iron in thesalts produced was reduced to Fe2+(aq). The solution was made up to a totalvolume of 100 cm3.

A 25.0 cm3 portion of the solution required 14.0 cm3 of 0.0200 mol dm–3 KMnO4 toreach the end-point.

Calculate the percentage of iron in the ore.

...................................................................................................................................[8]

ForExaminer’s

Use

© UCLES 2006



7


(c) High-strength low-alloy (HSLA) steels are used to fabricate TV masts and long spanbridges. They contain very low amounts of phosphorus and sulphur, but about 1%copper, to improve resistance to atmospheric corrosion. When dissolved in nitric acid, asample of this steel gives a pale blue solution.

(i) What species is responsible for the pale blue colour?

...................................................................................................................................

(ii) Describe and explain what you would see when dilute aqueous ammonia is addedto this solution.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[4]

[Total: 14]

ForExaminer’s

Use

© UCLES 2006



8

9701/04/M/J/06

4 The amino acids tyrosine, lysine and glycine are constituents of many proteins.

(a) State the reagents and conditions you could use to break proteins down into aminoacids.

..................................................................................................................................... [2]

(b) Draw a ring around each chiral centre in the above molecules. [1]

(c) In aqueous solution amino acids exist as zwitterions. Draw the zwitterionic structure ofglycine.

..................................................................................................................................... [1]

(d) For each of the following reactions, draw the structure of the organic compound formed.

(i) glycine + excess NaOH(aq)

...................................................................................................................................

(ii) tyrosine + excess NaOH(aq)

...................................................................................................................................

ForExaminer’s

Use

© UCLES 2006

CH2

C

O

CH

OH

tyrosine

H2N OH

(CH2)4

NH2

C

O

CH

lysine

H2N OH

H

C

O

CH

glycine

H2N OH



9


(iii) lysine + excess HCl (aq)

...................................................................................................................................

(iv) tyrosine + excess Br2(aq)

...................................................................................................................................[5]

(e) Draw the structural formula of a tripeptide formed from all three of these amino acids,showing clearly the peptide bonds.

..................................................................................................................................... [2]

(f) The formula of part of the chain of a synthetic polyamide is shown below.

(i) Identify the repeat unit of the polymer by drawing square brackets around it on theabove formula.

(ii) Draw the structures of the two monomers from which the polymer could be made.

...................................................................................................................................[3]

[Total: 14]

ForExaminer’s

Use

© UCLES 2006

CH2 CH2 CH2NH NH NHCO COCO CH2 CH2NH NHCO



10

9701/04/M/J/06

5 Benzocaine is an important local anaesthetic used in skin creams for sprains and othermuscular pains. It can be made by the following route.

(a) Suggest reagents and conditions for each of the above four reactions.

I ...................................................................................................................................

II ...................................................................................................................................

III ...................................................................................................................................

IV .............................................................................................................................. [6]

(b) Draw steps to show the mechanism of reaction I.

[2]

(c) Another local anaesthetic is amylocaine, which can be made from compound X.

(i) Apart from the benzene ring, name two functional groups in the molecule ofcompound X.

...................................................................................................................................

...................................................................................................................................

ForExaminer’s

Use

© UCLES 2006

CH3

I

CH3

NO2

II

CO2H

NO2

III

CO2H

NH2

IV

CO2CH2CH3

NH2

benzocaine

amylocaineX

CH2

CH3CH2CH3

NH2C

CO

OCH2

CH3

CH3

CH3

CH2CH3

NCCO

O



11

9701/04/M/J/06

(ii) Explain whether compound X would be more or less basic than benzocaine.

...................................................................................................................................

...................................................................................................................................[3]

[Total: 11]

ForExaminer’s

Use

© UCLES 2006



12

9701/04/M/J/06

BLANK PAGE






SP (KN) T32180/4© UCLES 2007 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Subsidiary Level and Advanced Level

*6631076049*

CHEMISTRY 9701/04

Paper 4 Structured Questions May/June 2007

1 hour 45 minutes

Candidates answer on the Question Paper.

Additional Materials: Data Booklet


Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluidDO NOT WRITE IN ANY BARCODES.

Section AAnswer all questions.

Section BAnswer all questions.

You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.

At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.


1

2

3

4

5

6

7

8

9

Total



2

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

Section A

Answer all questions in the spaces provided.

1 Zinc chloride is one of the most important compounds of zinc. It is used in dry cell batteries, as a flux for soldering and tinning, as a corrosion inhibitor in cooling towers and in the manufacture of rayon.

(a) Draw a fully labelled diagram to show how you could use a standard hydrogen electrode to measure the standard electrode potential, E o, of zinc.

[6]

(b) The electrolysis of zinc chloride can give different electrode products, depending on the conditions used.

Suggest the products formed at each electrode in the following cases. One space has been filled in for you.

conditions product at anode product at cathode

ZnCl2(l) chlorine

ZnCl2(concentrated aqueous)

ZnCl2(dilute aqueous)

[3]

(c) Use the following data, together with relevant data from the Data Booklet, to construct a Born-Haber cycle and calculate a value for the lattice energy of zinc chloride.

standard enthalpy change of formation of ZnCl2 –415 kJ mol–1

standard enthalpy change of atomisation of Zn(s) +131 kJ mol–1

electron affinity per mole of chlorine atoms –349 kJ mol–1

lattice energy = ............................................... kJ mol–1 [3]



3


ForExaminer’s

Use

© UCLES 2007

(d) Zinc is an essential element for plant and animal life. It is often administered in the form of a chelate, which is a complex between a metal ion and a polydentate ligand.

The rate of the reaction between zinc ions and the ligand 4-(2-pyridylazo)resorcinol, PAR, has been studied.

Zn2+ + 2

HO

HO

PAR

N N Zn2+

HO

–O

Zn-PAR

N

NN

N + 2H+

2

Both PAR and its zinc complex absorb radiation in the UV-visible region. The figure below shows their absorption spectra.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

abso

rban

ce

300 400 500

wavelength / nm

600 700

PAR Zn-PAR

(i) Devise a suitable experimental technique for studying how the rate of this reaction varies with [Zn2+(aq)].

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Describe a reaction you could carry out to show that PAR is a phenol.

..................................................................................................................................

.................................................................................................................................. [7]

[Total: 19]



4

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

2 (a) Write an equation showing the reaction that occurs when calcium nitrate, Ca(NO3)2, is heated.

......................................................................................................................................[1]

(b) Describe and explain the trend in thermal stability of the nitrates of the Group II elements.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(c) Gently heating ammonium nitrate, NH4NO3, in a test tube produces a mixture of two gases A and B. No residue remains in the tube.

The mass spectrum of gas A contains peaks at m/e (mass number) values of 16, 17 and 18, whereas that of gas B has peaks at m/e values of 14, 16, 28, 30 and 44.

(i) Identify the peaks in the mass spectra, and suggest the molecular formulae of the gases A and B.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Hence suggest an equation for the thermal decomposition of ammonium nitrate.

.................................................................................................................................. [5]

[Total: 9]



5


ForExaminer’s

Use

© UCLES 2007

3 Carbon forms two stable oxides, CO and CO2. Lead forms three oxides: yellow PbO, black PbO2 and red Pb3O4.

(a) Carbon monoxide burns readily in air. Heating black lead oxide produces oxygen gas, leaving a yellow residue.

(i) Suggest a balanced equation for each reaction.

..................................................................................................................................

..................................................................................................................................

(ii) Explain how these two reactions illustrate the relative stabilities of the +2 and +4 oxidation states down Group IV.

..................................................................................................................................

.................................................................................................................................. [3]

(b) Red lead oxide contains lead atoms in two different oxidation states.

(i) Suggest what these oxidation states are, and calculate the ratio in which they occur in red lead oxide.

..................................................................................................................................

..................................................................................................................................

(ii) Predict the equation for the action of heat on red lead oxide.

..................................................................................................................................

When red lead oxide is heated with dilute nitric acid, HNO3, a solution of lead(II) nitrate is formed and a black solid is left.

(iii) Suggest an equation for this reaction.

..................................................................................................................................

(iv) Explain how this reaction illustrates the relative basicities of the two oxidation states of lead.

..................................................................................................................................

.................................................................................................................................. [5]

(c) Both tin(II) oxide and tin(IV) oxide are amphoteric.

Write a balanced equation for the reaction between tin(II) oxide and aqueous sodium hydroxide.

......................................................................................................................................[1]

[Total: 9]



6

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

4 The following passage is taken from an A level Chemistry text book.

“In an isolated atom, the five d-orbitals have the same energy. In an octahedral complex ion, however, the presence of the ligands splits the five orbitals into a group of three and a group of two. These two groups have slightly different energies.”

(a) Use the following sets of axes to draw the shape of one d-orbital in each of the two groups mentioned above.

[2]

(b) Explain how the presence of the six ligands, L, in [FeL6]3+ splits the 3d orbitals into two groups of different energy, and explain whether the two-orbital group or the three-orbital group has the higher energy.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]



7


ForExaminer’s

Use

© UCLES 2007

(c) The following table lists the colours and energies of photons of light of certain wavelengths.

wavelength / nm

energy of photon

colour of photon

400 high violet

450 ↓ blue

500 lower green

600 ↓ yellow

650 low red

The visible spectra of solutions of two transition metal complexes C and D are shown in the diagram below.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

abso

rban

ce

300 400 500

wavelength / nm

600 700

CD

(i) A list of possible colours for these complexes is as follows.

yellow red green blue

Choose one of these words to describe the observed colour of each solution.

solution C ............................................ solution D ................................................

(ii) In which complex, C or D, will the energy gap between the two groups of orbitals be the larger? Explain your answer.

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 8]



8

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

5 The following scheme shows some reactions of methylbenzene.

CH3

Cl

I II

III

CH3 CH2Cl

E

F

IV

CO2H COCl

G

(a) Suggest reagents and conditions for reactions I to IV.

I ........................................................................................................................................

II .......................................................................................................................................

III ......................................................................................................................................

IV ..................................................................................................................................... [4]

(b) What type of reaction is each of the following?

reaction I ..........................................................................................................................

reaction III ........................................................................................................................ [2]



9


ForExaminer’s

Use

© UCLES 2007

(c) Compound F can be converted into 2-phenylethylamine in a two-stage process. Suggest a structure for the intermediate, H, in the box below, and suggest reagents and conditions for the steps V and VI.

CH2Cl

V VI

CH2CH2NH2

HF

reagents and conditions for step V ..................................................................................

reagents and conditions for step VI ................................................................................. [4]

(d) The compounds E, F and G react at different rates with nucleophilic reagents. Draw structures for the products of each compound with the following reagents.

If no reaction occurs, write “no reaction” in the box.

compoundreagent

cold water hot NaOH(aq)

E

F

G

[6]

[Total: 16]



10

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

6 Chemists use skeletal or partial-skeletal formulae to represent larger structures. For example the structure

CH3CH2

CH2

CH2

CH2

H2C

H2C CH

CC H

OH

may also be represented as follows.

CH3H

H

OH

Oestradiol is one of the hormones that controls the reproductive cycle in female mammals.

CH3

H

H

H

H

HO

HO

oestradiol

(a) (i) On the above structure of oestradiol, circle one chiral centre.

(ii) What is the total number of chiral centres in the oestradiol molecule? ..................... [2]

(b) Complete the following part-structures (which have the -OH groups removed) to show the products obtained when oestradiol (above) is reacted with the stated reagents.

(i) sodium metal

CH3

H

H

H



11


ForExaminer’s

Use

© UCLES 2007

(ii) Br2(aq)

CH3

H

H

H

(iii) NaOH(aq)

CH3

H

H

H

(iv) CH3COCl

CH3

H

H

H

(v) hot acidified K2Cr2O7

CH3

H

H

H

[7]

[Total: 9]



12

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

Section B – Applications of Chemistry


7 (a) (i) In a protein, amino acids are joined together by a process called condensation polymerisation. Addition polymerisation is used in some synthetic polymers, such as poly(propene).

State two important differences between condensation polymerisation and addition polymerisation.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Using the amino acids glycine and alanine shown, draw the displayed formula of the dipeptide ala-gly, clearly labelling the peptide link.

CO2HC

H

glycine

H

H2N CO2HC

CH3

alanine

H

H2N

[4]

(b) The diagram below shows a section of DNA. Identify the blocks labelled X, Y and Z.

X XA Z

X XC G

Y Y

X XC G

Y Y

Y Y

X ...................................... Y ...................................... Z ...................................... [3]



13


ForExaminer’s

Use

© UCLES 2007

(c) The table below shows the 3-base codes used by RNA.

UUUUUCUUAUUG

phepheleuleu

UCUUCCUCAUCG

serserserser

UAU UACUAA UAG

tyrtyr

stopstop

UGU UGCUGA UGG

cyscysstoptrp

CUUCUCCUACUG

leuleuleuleu

CCU CCCCCACCG

propropropro

CAU CACCAA CAG

hishisglngln

CGU CGCCGACGG

argargargarg

AUUAUCAUAAUG

ileileile

met/start

ACU ACCACAACG

thrthrthrthr

AAU AACAAA AAG

asnasnlyslys

AGU AGCAGA AGG

serserargarg

GUU GUCGUAGUG

valvalvalval

GCU GCCGCAGCG

alaalaalaala

GAU GACGAA GAG

aspaspgluglu

GGU GGCGGAGGG

glyglyglygly

(i) What amino acid sequence would the following base code produce? (You may use abbreviations in your answer.)

-AUGUCUAGAGACGGGUAA-

..................................................................................................................................

..................................................................................................................................

(ii) What would be the effect on the amino acid sequence if a mutation caused the base G at position 13 in the sequence to be replaced by U?

..................................................................................................................................

.................................................................................................................................. [3]

(d) (i) Name a disease which results from a genetic defect.

..................................................................................................................................

(ii) Explain how the genetic defect can bring about your named disease.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 13]



14

9701/04/M/J/07

ForExaminer’s

Use

© UCLES 2007

8 (a) Electrophoresis can be used to separate amino acids which are produced by the hydrolysis of a polypeptide.

Using glycine as an example, explain why the result of electrophoresis depends on pH.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) The diagram below shows the results of electrophoresis in neutral solution. At the start of the experiment a spot of a solution containing a mixture of amino acids P, Q, R and S was placed in the middle of the plate. Following electrophoresis the amino acids had moved to the positions shown in the lower diagram.

before + –

after + –

P Q R S

(i) Which amino acid existed mainly as a zwitterion in the buffer solution? Explain your answer.

..................................................................................................................................

..................................................................................................................................

(ii) Assuming amino acids R and S carry the same charge when in this buffer solution, which is likely to be the larger molecule? Explain your answer.

..................................................................................................................................

.................................................................................................................................. [2]

(c) Amino acids may also be separated by using two-dimensional paper chromatography. This involves putting a spot of the mixture on the corner of a piece of chromatography paper and allowing a solvent to soak up the paper. The paper is then dried, turned through 90° and placed in a second solvent. This method gives better separation than a one solvent method.

(i) Paper chromatography relies on partition between the solvent applied and another phase.

What is this second phase? .......................................................



15


ForExaminer’s

Use

© UCLES 2007

(ii) The table below shows the Rf values for some amino acids in two different solvents.

amino acid Rf solvent 1 Rf solvent 2

A 0.1 0.2

B 0.0 0.4

C 0.3 0.0

D 0.8 0.9

E 0.6 0.5

Use the grid below to plot the positions of the amino acids after two-dimensional paper chromatography using solvent 1 followed by solvent 2.

solvent 2

solvent 1

solventfront

solvent front

spot appliedhere

(iii) Which amino acid travelled fastest in both solvents? .................................

(iv) Which amino acid did not move at all in solvent 2? ................................. [5]

[Total: 10]



16

9701/04/M/J/07© UCLES 2007

9 (a) Graphite and buckminsterfullerene are two structural forms of carbon. By referring to diagrams of their structures, suggest three differences in their properties.

graphite buckminsterfullerene

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) Nano-sized ‘test-tubes’ can be formed from carbon structures. What is the relationship between the parts of these ‘test tubes’ and the two structural

forms of carbon shown above?

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(c) Many modern sunscreens contain nano-sized particles of titanium dioxide. This substance does not absorb ultraviolet radiation.

Suggest how these nano-particles are able to protect skin from ultraviolet radiation.

..........................................................................................................................................

......................................................................................................................................[1]

[Total: 7]

Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity.

University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.

ForExaminer’s

Use




SPA (SHW (00018 4/07) T51891/2© UCLES 2008 [Turn over



Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.DO NOT WRITE IN ANY BARCODES.





*7262307684*

CHEMISTRY 9701/04


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

10

Total



9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

Section A


1 Chlorine gas and iron(II) ions react together in aqueous solution as follows.

Cl 2 + 2Fe2+ 2Cl – + 2Fe3+

(a) The following diagram shows the apparatus needed to measure the E ocell for the above reaction.

V

S

A

B

CE

D

(i) In the spaces below, identify what the five letters A – E in the above diagram represent.

A .........................................................

B .........................................................

C .........................................................

D .........................................................

E .........................................................

(ii) Use the Data Booklet to calculate the E ocell for this reaction, and hence decide which direction (left to right, or right to left) electrons would flow through the voltmeter V when switch S is closed.

E ocell = .................................................. V

direction of electron flow ......................................................[7]

2



3


ForExaminer’s

Use

© UCLES 2008

(b) Iron(III) chloride readily dissolves in water.

FeCl 3(s) Fe3+(aq) + 3Cl –(aq)

(i) Use the following data to calculate the standard enthalpy change for this process.

species DH of / kJ mol–1

FeCl 3(s) –399.5

Fe3+(aq) –48.5

Cl –(aq) –167.2

DH o = .........................................kJ mol–1

(ii) A solution of iron(III) chloride is used to dissolve unwanted copper from printed circuit boards.

When a copper-coated printed circuit board is immersed in FeCl 3(aq), the solution turns pale blue.

Suggest an equation for the reaction between copper and iron(III) chloride and use the Data Booklet to calculate the E o for the reaction.

equation ...................................................................................................................

E o = .................................................. V[4]

[Total: 11]



4

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

2 This question is about the properties and reactions of the oxides of some elements in their +4 oxidation state.

(a) Chlorine dioxide, Cl O2, is an important industrial chemical, used to bleach wood pulp for making paper, and to kill bacteria in water supplies.

However, it is unstable and decomposes into its elements as follows.

2Cl O2(g) Cl 2(g) + 2O2(g)

(i) The chlorine atom is in the middle of the Cl O2 molecule. Using the chlorine-oxygen bond energy as 278 kJ mol–1, and other values from the Data Booklet, calculate DH for the above reaction.

DH = ........................................ kJ mol–1

(ii) Assuming the Cl -O bonds in chlorine dioxide are double bonds, predict the shape of the Cl O2 molecule. Explain your answer.

..................................................................................................................................

..................................................................................................................................

(iii) Cl O2 can be made in the laboratory by reacting KCl O3 with concentrated H2SO4. Other products are K2SO4, KCl O4 and H2O.

Construct a balanced equation for this reaction. You may find the use of oxidation numbers helpful.

..................................................................................................................................[5]

(b) Sulphur dioxide is an atmospheric pollutant.

(i) State two sources of atmospheric SO2 that arise from human activity.

..................................................................................................................................

..................................................................................................................................

(ii) Explain why SO2 is a pollutant, and state an environmental consequence of this pollution.

..................................................................................................................................

..................................................................................................................................[3]



5


ForExaminer’s

Use

© UCLES 2008

(c) All the oxides of the elements in Group IV in their +4 oxidation state are high melting point solids except CO2.

(i) Explain this observation by describing the bonding in CO2, SiO2 and SnO2.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) State the difference in the thermal stabilities of SnO2 and PbO2. Illustrate your answer with an equation.

..................................................................................................................................

..................................................................................................................................

CO2 dissolves in water to form a weakly acidic solution containing the hydrogencarbonate ion.

(iii) Write an equation for the reaction of CO2 with water, and write an expression for the equilibrium constant, Kc.

..................................................................................................................................

..................................................................................................................................

(iv) Explain the role of the hydrogencarbonate ion in controlling the pH of blood, illustrating your answer with relevant equations.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[7]

[Total: 15]



6

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

3 The elements of Group IV all form tetrachlorides with the general formula M Cl 4.

(a) Draw a diagram of a molecule of SiCl 4 stating bond angles.

[2]

(b) Describe and explain how the volatilities of the Group IV chlorides vary down the group.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(c) The relative stabilities of the M 2+(aq) and M 4+(aq) ions also vary down Group IV.

(i) Use the Data Booklet to illustrate this observation when M = Sn and M = Pb.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Use the Data Booklet to predict the products formed, and write equations for the reactions occurring, when

• an equimolar mixture of Sn2+(aq) and Sn4+(aq) is added to I2(aq),

..................................................................................................................................

..................................................................................................................................

• an equimolar mixture of Pb2+(aq) and Pb4+(aq) is added to SO2(aq).

..................................................................................................................................

..................................................................................................................................[4]



7


ForExaminer’s

Use

© UCLES 2008

(d) (i) The Sn–Cl bond energy is +315 kJ mol–1. Use this and other values from the Data Booklet to calculate DH o for the reaction

M Cl 2(g) + Cl 2(g) M Cl 4(g)

for the following cases.

• M = Si

DH o = ........................................ kJ mol–1

• M = Sn

DH o = ........................................ kJ mol–1

(ii) Do your results agree with the trend in relative stabilities of the +2 and +4 oxidation states in (c)? Explain your answer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[3]

[Total: 11]



8

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

4 Recently much interest has been shown in the production of the fuel biodiesel from algae. Up to 55% of the mass of the dried algae is composed of lipids, the majority of which are triglycerides.

To convert triglycerides into biodiesel, the following processes are carried out.

C17H35CO2CH2

3C17H35CO2H

C17H35CO2H

C17H35CO2CH2

a triglyceride, Mr = 890

biodiesel, Mr = 298

C17H35CO2CH

CH2OH

C17H35CO2CH3

CH2OH

glycerol

CHOH +I

II

(a) Name the functional group present in triglycerides.

.................................................................................................................................... [1]

(b) Suggest reactants and conditions for

reaction I,

..........................................................................................................................................

reaction II.

..........................................................................................................................................[4]

(c) Suggest the structural formula of the compound formed when glycerol is reacted with

(i) an excess of HBr(aq),

..................................................................................................................................

(ii) an excess of hot acidified K2Cr2O7(aq).

..................................................................................................................................[2]



9


ForExaminer’s

Use

© UCLES 2008

(d) Calculate the mass of biodiesel that can be produced from 1000 kg of dried algae, assuming that 50% of the algal mass is triglycerides.

mass = ........................................... kg [2]

(e) (i) Construct an equation for the complete combustion of biodiesel.

..................................................................................................................................

(ii) Use your equation to calculate the mass of CO2 produced when 10 kg of biodiesel is burned.

..................................................................................................................................

..................................................................................................................................[3]

(f) The production of biodiesel is at present an expensive process.

Suggest a reason why the development of biodiesel as an alternative to fossil fuels is important.

..........................................................................................................................................

.................................................................................................................................... [1]

[Total: 13]



10

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

5 Both ethene and benzene react with bromine, but the mechanisms and the types of products of the two reactions are different.

Br2

Br

BrCH2CH2BrH2C CH2 +

HBr+

reaction I

no heat, no light, no catalyst needed

Br2+reaction II

heat and catalyst needed

(a) State the type of reaction undergone in each of reactions I and II.

reaction I

..........................................................................................................................................

reaction II

..........................................................................................................................................[2]



11


ForExaminer’s

Use

© UCLES 2008

(b) In each of reactions I and II, the intermediate is a bromine-containing cation. In each of the following boxes, draw the intermediate and use curly arrows to show how it is converted into the product.

reaction I product

intermediate

reaction II product

intermediate

[4]

(c) Why do ethene and benzene differ in their reaction with bromine?

..........................................................................................................................................

.................................................................................................................................... [1]

[Total: 7]



12

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

6 The substituted benzene compound

Y

can be further substituted.

If Y is an electron-withdrawing group, the next substitution will be in position 3. If Y is an electron-releasing group, the next substitution will be mostly in position 4.

X + X

if Y is electron-withdrawing

+ X

if Y is electron-releasing

YYY

X

The following table lists some electron-withdrawing and electron-releasing substituents.

electron-withdrawing groups electron-releasing groups

–NO2 –CH3

–COCH3 –CH2Br

–CO2H –NH2

Use the above information to draw relevant structural formulae in the boxes in the schemes below.

CH3

(i)(ii) H+

KMnO4 + OH–

(i)(ii) H+

KMnO4 + OH–

(i)(ii) OH–

Sn + HCl

Br2 + Al Cl 3

EDC

BA

HNO3 + H2SO4

[5]

[Total: 5]



13


ForExaminer’s

Use

© UCLES 2008

7 Each of the following structures is an 8-atom segment of the chain of a commercial polymer.

For each structure,

• decide whether it is part of a condensation or an addition polymer, and • draw the structural formulae of the monomer(s) from which the polymer is made.

polymeraddition or

condensation?formulae of monomers

HN

HN

CH2

CH2

O

C

HN

O

C

O

C

O

O O

C

CH2

CH2 CH2

CH3

CH3

CH CH

O

C

CONH2

CH2

CH

CH2

CH

CH2

CH

CH2

CH

CH3 CONH2

[8]

[Total: 8]



14

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008



8 (a) State and show, using suitable diagrams, the types of bonding that occur in the primary, secondary and tertiary structures of a protein.

primary

secondary

tertiary

[6]

(b) Analysis of a polypeptide A showed that the amino-(N-)terminal end is methionine (met) and that the carboxyl-(C-)terminal end is lysine (lys).

Enzymic hydrolysis of the polypeptide produced the following tripeptides, with the amino acid residue on the left having the free amino group.

met-ala-gly gly-arg-val ala-gly-arg arg-val-lys ala-gly-ala gly-ala-gly

Work out the sequence of amino acids in A, using the 3-letter abbreviations. Use each tripeptide once only.

[2]



15


ForExaminer’s

Use

© UCLES 2008

(c) Give two examples of how interchanging the positions of two amino acids could affect the bonding in, and hence the overall structure of, the protein.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [4]

[Total: 12]



16

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

9 Much of the preparation of evidence to solve crimes now relies on instrumental analysis. This question deals with some of the techniques used.

(a) Electrophoresis can be used to separate amino acids produced by hydrolysing proteins. The amino acids are placed in a buffered solution in an electric field. In a solution of given pH, what two factors affect the movement of a given amino acid?

(i) ..................................................................................................................................

(ii) ..................................................................................................................................[2]

(b) Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry are also used in the detection of certain molecules, particularly those containing hydrogen atoms.

(i) Explain how and why the NMR spectrum of propanal, CH3CH2CHO, would be different from that of propanone, CH3COCH3, which contains the same atoms.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Explain how and why the mass spectrum of the two compounds in (i) would be different.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]



17


ForExaminer’s

Use

© UCLES 2008

(c) At one time, bromomethane, CH3Br, was widely used to control insect pests in agricultural crops and timber. It is now known to break down in the stratosphere and contribute to the destruction of the ozone layer.

Samples can be screened for traces of bromomethane by subjecting them to mass spectrometry.

(i) Which peak(s) would show the presence of bromine in the compound?

..................................................................................................................................

(ii) How could you tell by studying the M and M+2 peaks that the compound contained bromine rather than chlorine?

..................................................................................................................................

..................................................................................................................................[3]

[Total: 9]



18

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

10 (a) A number of drugs, such as insulin for diabetics, are delivered by injection rather than by mouth (oral delivery). Suggest two reasons why this might be necessary.

(i) ..................................................................................................................................

..................................................................................................................................

(ii) ..................................................................................................................................

..................................................................................................................................[2]

(b) Many patients prefer oral delivery to injection, and a number of methods for overcoming the problems of oral delivery are being investigated. Several of these use nanotechnology.

Study the passage and diagram and then answer the questions that follow.

At a 2004 meeting, engineers from the University of Texas described their research into nanospheres for oral drug delivery. Nanospheres can transport a drug safely through the hostile environment of the stomach.

The nanospheres are created from hydrogels which are stable, organic materials formed from a network of polymer chains. Hydrogels have a variety of uses including disposable nappies, soft contact lenses, dressings for burns and, more recently, drug delivery.The drug is contained in the hydrogel nanosphere as shown in the diagram below. Hydrogels absorb water and swell at a rate dependent on the pH of their environment. As the hydrogel swells, the drug is released.

capsulecontaining nanospheres nanosphere

hydrogelcoat

drug

(i) What is a nanosphere?

..................................................................................................................................

(ii) Suggest why the stomach might be a particularly hostile environment for drugs.

..................................................................................................................................

..................................................................................................................................



19

9701/04/M/J/08

ForExaminer’s

Use

© UCLES 2008

(iii) Suggest two ways in which the nanosphere shown in the diagram can be modified to change the rate of drug release.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

(c) Hydrogels may be formed as homopolymers (using a single monomer), or heteropolymers (using two or more different monomers).

By using the monomers below, you are to draw sections of both a homopolymer and a heteropolymer. Each of your drawings should show a three-monomer section of the polymer.

HOCH2CH2OH HO2CCHRNH2 HO2CCH(OH)CH2CO2H

homopolymer

heteropolymer

[3]

[Total: 9]



20

9701/04/M/J/08

BLANK PAGE





This document consists of 18 printed pages and 2 blank pages.

SP (FF/DT) T69679/1© UCLES 2009 [Turn over








*0737714930*

CHEMISTRY 9701/04


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

Total



2

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

Section A


1 (a) Explain what is meant by the Bronsted-Lowry theory of acids and bases.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(b) The Ka values for some organic acids are listed below.

acid Ka /mol dm−3

CH3CO2H 1.7 � 10−5

Cl CH2CO2H 1.3 � 10−3

Cl 2CHCO2H 5.0 � 10−2

(i) Explain the trend in Ka values in terms of the structures of these acids.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Calculate the pH of a 0.10 mol dm−3 solution of Cl CH2CO2H.

pH = ...........................................



3

9701/04/M/J/09© UCLES 2009 [Turn over

ForExaminer’s

Use

(iii) Use the following axes to sketch the titration curve you would obtain when 20 cm3 of 0.10 mol dm−3 NaOH is added gradually to 10 cm3 of 0.10 mol dm−3 Cl CH2CO2H.

00 5 10 15 20

7pH

volume of NaOH added / cm3

14

[8]

(c) (i) Write suitable equations to show how a mixture of ethanoic acid, CH3CO2H, and sodium ethanoate acts as a buffer solution to control the pH when either an acid or an alkali is added.

..................................................................................................................................

..................................................................................................................................

(ii) Calculate the pH of a buffer solution containing 0.10 mol dm−3 ethanoic acid and 0.20 mol dm−3 sodium ethanoate.

pH = ........................................... [4]

[Total: 14]



4

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

2 (a) Describe the observations you would make when concentrated sulfuric acid is added to separate portions of NaCl (s) and NaBr(s). Write an equation for each reaction that occurs.

NaCl (s): observation ................................................................................................

......................................................................................................................

equation

NaBr(s): observation ................................................................................................

......................................................................................................................

equation

[4]

(b) By quoting relevant E o- data from the Data Booklet, explain how the observations you have described above relate to the relative oxidising power of the elements.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) By referring to relevant E o- data choose a suitable reagent to convert Br2 into Br −. Write an equation and calculate the E o- for the reaction.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

[Total: 9]



5


ForExaminer’s

Use

3 (a) Explain what is meant by the term transition element.

..........................................................................................................................................

..................................................................................................................................... [1]

(b) Complete the electronic configuration of

(i) the vanadium atom, 1s22s22p6 .......................................................................

(ii) the Cu2+ ion. 1s22s22p6 ....................................................................... [2]

(c) List the four most likely oxidation states of vanadium.

..................................................................................................................................... [1]

(d) Describe what you would see, and explain what happens, when dilute aqueous ammonia is added to a solution containing Cu2+ ions, until the ammonia is in an excess.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [5]

(e) Copper powder dissolves in an acidified solution of sodium vanadate(V), NaVO3, to produce a blue solution containing VO2+ and Cu2+ ions.

By using suitable half-equations from the Data Booklet, construct a balanced equation for this reaction.

..................................................................................................................................... [2]

[Total: 11]



6

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

4 (a) The reaction between iodide ions and persulfate ions, S2O 82−, is slow.

2I− + S2O 82− I2 + 2SO 4

2− 1

The reaction can be speeded up by adding a small amount of Fe2+ or Fe3+ ions. The following two reactions then take place.

2I− + 2Fe3+ I2 + 2Fe2+ 2

2Fe2+ + S2O 82− 2Fe3+ + 2SO 4

2− 3

(i) What type of catalysis is occurring here?

..................................................................................................................................

(ii) The rates of reactions 2 and 3 are both faster than that of reaction 1. By considering the species involved in these reactions, suggest a reason for this.

..................................................................................................................................

..................................................................................................................................

(iii) The following reaction pathway diagram shows the enthalpy profile of reaction 1.

enthalpy

progress of reaction

Use the same axes to draw the enthalpy profiles of reaction 2 followed by reaction 3, starting reaction 2 at the same enthalpy level as reaction 1.

[4]



7


ForExaminer’s

Use

(b) The oxidation of SO2 to SO3 in the atmosphere is speeded up by the presence of nitrogen oxides.

(i) Describe the environmental significance of this reaction.

..................................................................................................................................

(ii) Describe a major source of SO2 in the atmosphere.

..................................................................................................................................

(iii) By means of suitable equations, show how nitrogen oxides speed up this reaction.

..................................................................................................................................

.................................................................................................................................. [4]

[Total: 8]



8

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

5 (a) In the following boxes draw the structural formulae of three alcohols having straight (i.e. unbranched) chains, with the molecular formula C5H12O.

A B C

[2]

Use the letters A, B or C as appropriate when answering the following questions. Each letter may be used once, more than once or not at all.

(b) Which of the alcohols are chiral? .................................................................................. [1]

(c) (i) Which of these alcohols react with alkaline aqueous iodine? ...................................

(ii) Describe the observation you would make during this reaction.

..................................................................................................................................

(iii) Draw the structural formulae of the products of this reaction.

[4]

(d) Draw the structural formula of the product obtained when each of the alcohols A, B and C is heated with an excess of acidified K2Cr2O7(aq).

A

B

C

[3]



9


ForExaminer’s

Use

(e) One of the many suggestions for converting biomass into liquid fuel for motor transport is the pyrolysis (i.e. heating in the absence of air) of cellulose waste, followed by the synthesis of alkanes.

(i) In the first reaction, cellulose, (C6H10O5)n, is converted into a mixture of carbon monoxide and hydrogen. Some carbon is also produced.

Complete and balance the equation for this reaction.

(C6H10O5)n ————————— + ————————— + —————————

(ii) The second reaction involves the combination of CO and H2 to produce alkanes such as heptane.

7CO + 15H2 C7H16 + 7H2O heptane

Using the value of 1080 kJ mol−1 as the value for the C�O bond energy in CO, and other relevant bond energies from the Data Booklet, calculate the ∆H for this reaction.

∆H = ......................................... kJ mol−1 [5]

[Total: 15]



10

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

6 Phenol and chlorobenzene are less reactive towards certain reagents than similar non-aromatic compounds.

Thus hexan-1-ol can be converted into hexylamine by the following two reactions,

I IICH3(CH2)5OH CH3(CH2)5Cl CH3(CH2)5NH2

hexan-1-ol 1-chlorohexane hexylamine

whereas neither of the following two reactions takes place.

OH Cl NH2

(a) (i) Suggest reagents and conditions for

reaction I, ............................................................................................................... ,

reaction II. ............................................................................................................... .

(ii) What type of reaction is reaction II? ..........................................................................

(iii) Suggest a reason why chlorobenzene is much less reactive than 1-chlorohexane.

..................................................................................................................................

.................................................................................................................................. [4]



11


ForExaminer’s

Use

(b) Phenylamine can be made from benzene by the following two reactions.

NH2NO2III IV

(i) Suggest reagents and conditions for

reaction III, .............................................................................................................. ,

reaction IV. .............................................................................................................. .

(ii) State the type of reaction for

reaction III, .............................................................................................................. ,

reaction IV. .............................................................................................................. . [5]

(c) Suggest a reagent that could be used to distinguish phenylamine from hexylamine.

reagent and conditions ....................................................................................................

observation with phenylamine ..........................................................................................

observation with hexylamine .............................................................................................[2]



12

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

(d) Phenylamine is used to make azo dyes. In the following boxes draw the structural formula of the intermediate D and of the azo dye E.

D

E

NH2

NaNO2 + HCl

in NaOH(aq)

T < 5°COH

CH3

CH3

[2]

[Total: 13]



13


ForExaminer’s

Use

Section B


7 Metals play a vital part in biochemical systems. In this question you need to consider why some metals are essential to life, whilst others are toxic.

(a) For each of the metals, state where it might be found in a living organism, and what its chemical role is.

iron location in organism .....................................................................................

role ...............................................................................................................

......................................................................................................................

sodium location in organism .....................................................................................

role ...............................................................................................................

......................................................................................................................

zinc location in organism .....................................................................................

role ...............................................................................................................

...................................................................................................................... [6]

(b) Heavy metals such as mercury are toxic, and it is important that these do not enter the food chain.

(i) Give a possible source of mercury in the environment.

..................................................................................................................................

(ii) Describe and explain two reasons why mercury is toxic, using diagrams and/or equations to help your explanation.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [4]

[Total : 10]



14

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

8 A large number of organic compounds are soluble in both water and non-aqueous solvents such as hexane. If such a compound is shaken with a mixture of water and the non-aqueous solvent, it will dissolve in both solvents depending on the solubility in each.

(a) (i) State what is meant by the term partition coefficient.

..................................................................................................................................

..................................................................................................................................

(ii) When 100 cm3 of an aqueous solution containing 0.50 g of an organic compound X was shaken with 20 cm3 of hexane, it was found that 0.40 g of X was extracted into the hexane.

Calculate the partition coefficient of X between hexane and water.

(iii) If two 10 cm3 portions of hexane were used instead of a single 20 cm3 portion, calculate the total amount of X extracted and compare this with the amount extracted using one 20 cm3 portion.

[5]



15


ForExaminer’s

Use

(b) PCBs are highly toxic compounds released into the atmosphere when some plastics are burned at insufficiently high temperatures. In recent years PCB residues have been found in the breast milk of Inuit mothers in northern Canada. Foods, such as oily fish, seal and whale meat, which are high in fat, form an important part of the Inuit diet.

(i) Suggest why berries and drinking water are not contaminated by PCBs in the same way that oily fish, seal and whale meat are.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Based on the information provided, what can you say about the partition coefficient between fat and water for PCB residues?

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [3]



16

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

(c) The diagram shows the result of two-way paper chromatography.

Xstarting point

solvent 1

solvent2

(i) How many spots were there after the first solvent had been used?

...................................

(ii) Circle the spot that moved very little in solvent 2, but moved a greater distance in solvent 1.

(iii) Draw a square around the spot that could be separated from the rest by using only solvent 1.

[3]

[Total: 11]



17

9701/04/M/J/09© UCLES 2009

ForExaminer’s

Use

9 (a) Spider silk is a natural polymer which has an exceptional strength for its weight. Kevlar is a man-made polymer designed to have similar properties. It has a wide variety of uses from sporting equipment to bullet-proof vests.

C

O

H

N

H

N

O

C

N

HC

O

O

C

N

H

O

C

Kevlar

(i) In Kevlar, the polymer strands line up to form strong sheets with bonds between the strands.

On the diagram above, draw part of a second polymer chain showing how bonds could be formed between the chains.

(ii) Suggest what type of bonds these are.

..................................................................................................................................

(iii) Draw two possible monomer molecules for making the polymer Kevlar.

[5]



18

9701/04/M/J/09© UCLES 2009

(b) The transport of oil by sea has resulted in a number of oil spills in recent years. As well as a waste of a valuable resource, these have caused major environmental problems. Traditional sorbent materials absorb water and sink. Researchers have developed new sorbent materials to help collect the spilled oil. The sorbent consists of a material called ‘hydrophobic aerogels’. This is a network of silicon(IV) oxide with some of the silicon atoms attached to fluorine-containing groups.

—O—Si—CH2—CF3

The introduction of these fluorine-containing groups allows the oil to be absorbed but not the water. Tests show that these materials can absorb more than 200 times their mass of oil without sinking.

(i) Suggest what the word hydrophobic means.

..................................................................................................................................

(ii) Suggest why the fluorine-containing groups allow oil to pass through but not water molecules.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Suggest another important fluorine-containing polymer that repels water-containing materials.

..................................................................................................................................[4]

[Total: 9]



19

9701/04/M/J/09

BLANK PAGE



20

9701/04/M/J/09



BLANK PAGE




DC (CW/DJ) 25442/4© UCLES 2010 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Level







*8342870404*

CHEMISTRY 9701/41


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

10

Total

www.XtremePapers.net


2

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

Section A


1 (a) Phosphorus and sulfur are two non-metallic elements on the right hand side of the Periodic Table.

For each of these elements describe the observations you would make when it burns in air, and write a balanced equation for the reaction.

phosphorus

observation ......................................................................................................................

equation ...........................................................................................................................

sulfur

observation ......................................................................................................................

equation ........................................................................................................................... [4]

(b) White phosphorus, P4, is produced commercially by heating calcium phosphate(V) rock with a mixture of silica, SiO2, and coke in an electric furnace at 1400 °C. Calcium silicate, CaSiO3, and carbon monoxide are the other products.

(i) Balance the following equation which represents the overall process.

___ Ca3(PO4)2 + ___ SiO2 + ___ C ___ P4 + ___ CaSiO3 + ___ CO

When heated to 400 °C in the absence of air, white phosphorus is changed into the red form of the element. The following table lists some of the properties of the two forms, which are known as allotropes.

allotropeelectrical

conductivitymelting point

/ °Csolubility in

watersolubility in benzene

white none 44 insoluble soluble

red none 500 insoluble insoluble

(ii) Suggest the type of structure and bonding in each allotrope.

allotrope type of structure type of bonding

white

red



3


ForExaminer’s

Use

(iii) In both allotropes, phosphorus has a valency of 3. Suggest by means of diagrams how the phosphorus atoms might be joined together in each allotrope.

white phosphorus

red phosphorus

[7]

[Total: 11]



4

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

2 (a) Describe three characteristic chemical properties of transition elements that are not shown by Group II elements.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(b) When NH3(aq) is added to a green solution containing Ni2+(aq) ions, a grey-green precipitate is formed. This precipitate dissolves in an excess of NH3(aq) to give a blue-violet solution.

Suggest an explanation for these observations, showing your reasoning and including equations for the reactions you describe.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [4]

(c) Dimethylglyoxime, DMG, is a useful reagent for the quantitative estimation of nickel. It forms an insoluble salt with nickel ions according to the following equation.

Ni2+(aq) + C4H8N2O2 NiC4H6N2O2(s) + 2H+(aq) DMG Ni-DMG

A small coin of mass 3.40 g was dissolved in nitric acid and an excess of DMG was added. The precipitated Ni-DMG was filtered off, washed and dried. Its mass was 4.00 g.

Calculate the % of nickel in the coin.

percentage of nickel = ..................................% [3]

[Total: 10]



5


ForExaminer’s

Use

3 (a) Describe how the behaviour of the oxides of tin and lead in their +4 oxidation states differ on heating.

..........................................................................................................................................

...................................................................................................................................... [1]

(b) Explain the following by using data from the Data Booklet where appropriate, and writing equations for all reactions.

(i) A sample of liquid PbCl4 is placed in a flask and the flask is gently warmed. A gas is evolved and a white solid is produced. When the gas is bubbled through KI(aq), purple fumes are produced.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Repeating the same experiment using liquid SnCl4 instead of PbCl4 results in no evolution of gas, and no reaction with KI(aq).

..................................................................................................................................

..................................................................................................................................[4]

(c) The molecule dichlorocarbene, CCl2, can be produced under certain conditions. It is highly unstable, reacting with water to produce carbon monoxide and a strongly acidic solution.

(i) Suggest the electron arrangement in CCl2 and draw a dot-and-cross diagram showing this. Predict the shape of the molecule.

(ii) Construct an equation for the reaction of CCl2 with water.

..................................................................................................................................[3]

[Total: 8]



6

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

4 Ethanolamine and phenylamine are two organic bases that are industrially important. Ethanolamine is a useful solvent with basic properties, whilst phenylamine is an important starting material in the manufacture of dyes and pharmaceuticals.

The following table lists some of their properties, together with those of propylamine.

compound formula Mr boiling point/ °C solubility in water

propylamine CH3CH2CH2NH2 59 48 fairly soluble

ethanolamine HOCH2CH2NH2 61 170 very soluble

phenylamine NH2 93 184

sparingly soluble

(a) Suggest why the boiling point of ethanolamine is much higher than that of propylamine. Draw a diagram to illustrate your answer.

..........................................................................................................................................

..........................................................................................................................................

[2]

(b) Describe and explain the relative basicities of propylamine and phenylamine.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(c) Write an equation showing ethanolamine acting as a Brønsted-Lowry base.

...................................................................................................................................... [1]



7


ForExaminer’s

Use

(d) Propylamine can be synthesised from bromoethane by the following route.

CH3CH2Br CH3CH2CH2NH2

step 1

X

step 2

(i) Draw the structure of the intermediate compound X in the box above.

(ii) Suggest reagents and conditions for

step 1 ........................................................................................................................

step 2 ........................................................................................................................ [3]

(e) Apart from their relative basicities, ethanolamine and phenylamine differ in many of their reactions.

For each of these two compounds, describe one test that would give a positive result with the stated compound, but a negative result with the other.

ethanolamine

test ...................................................................................................................................

observation ......................................................................................................................

phenylamine

test ...................................................................................................................................

observation ...................................................................................................................... [4]

[Total: 12]



8

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

5 Although standard electrode potentials are measured for solutions where the concentrations of ions are 1.0 mol dm–3, cells used as sources of battery power tend to operate with more concentrated solutions. This question concerns the electrode reactions involved in the hydrogen-oxygen fuel cell and the lead-acid car battery.

(a) In the hydrogen-oxygen fuel cell, H2(g) and O2(g) are fed onto two inert electrodes dipping into NaOH(aq).

V

hydrogenoxygen

NaOH(aq)

The following reactions take place.

left hand electrode (cathode): H2(g) + 2OH–(aq) 2H2O(l) + 2e–

right hand electrode (anode): O2(g) + 2H2O(l) + 4e– 4OH–(aq)

(i) Use the Data Booklet to calculate E o––cell for this reaction.

..................................................................................................................................

(ii) Construct an equation for the overall reaction.

..................................................................................................................................

(iii) By using one of the phrases more positive, more negative or no change, deduce the effect of increasing [OH–(aq)] on the electrode potential of

• the left hand electrode .......................................................................

• the right hand electrode .......................................................................

(iv) Hence deduce whether the overall Ecell is likely to increase, decrease or remain the same, when [OH–(aq)] increases. Explain your answer.

..................................................................................................................................

..................................................................................................................................

(v) Suggest one other reason why a high [NaOH(aq)] is used in the fuel cell.

..................................................................................................................................[6]



9


ForExaminer’s

Use

(b) In the cells of a lead-acid car battery the following reactions take place.

cathode: Pb(s) Pb2+(aq) + 2e–

anode: PbO2(s) + 4H+(aq) + 2e– Pb2+(aq) + 2H2O(l)

(i) Use the Data Booklet to calculate E o––cell for this reaction.

..................................................................................................................................

(ii) Construct an equation for the overall reaction.

..................................................................................................................................

The electrolyte in a lead-acid cell is H2SO4(aq). Most of the Pb2+(aq) ions that are produced at the electrodes are precipitated as the highly insoluble PbSO4(s).

(iii) Construct an equation for the overall cell reaction in the presence of H2SO4.

..................................................................................................................................

(iv) By considering the effect of decreasing [Pb2+(aq)] on the electrode potentials of the cathode and the anode, deduce the effect of the presence of H2SO4(aq) in the electrolyte on the overall Ecell.

State whether the Ecell will increase, decrease or remain the same. Overall Ecell will ................................................ .

Explain your answer.

..................................................................................................................................

..................................................................................................................................[5]

[Total: 11]



10

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

6 Acyl chlorides are useful intermediates in organic syntheses.

(a) (i) State a suitable reagent for converting carboxylic acids into acyl chlorides.

..................................................................................................................................

(ii) Construct an equation for the reaction between ethanoic acid, CH3CO2H, and the reagent you have stated in (i).

..................................................................................................................................[2]

(b) (i) In the boxes provided draw the structures of the compounds formed when benzoyl chloride undergoes the following reactions.

C2H5OH

COCl

I II

A

NH3

B

(ii) Name the functional group in

• compound A ..................................................................

• compound B ................................................................. .

(iii) What type of reaction is reaction II?

..................................................................................................................................[5]



11


ForExaminer’s

Use

(c) (i) Suggest suitable acyl chlorides to use in the following reaction. Draw their structures in the boxes provided.

+ H2NNH2

NHHN

O O

OH

OHO

O

C E

O

O On

+

D F

Compound E dissolves in, but does not react with, cold water.

(ii) Suggest the major type of intermolecular interaction that occurs between E and water.

..................................................................................................................................

(iii) A solution of the diamine H2NCH2CH2NH2 in water has pH = 11 but a solution of E in water has pH = 7. Suggest why this is the case.

..................................................................................................................................

..................................................................................................................................

(iv) What type of polymer is compound F?

..................................................................................................................................[5]

[Total: 12]



12

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

7 Predict the products of the following reactions and draw their structures in the boxes provided. Note that the molecular formula of the final product is given in each case.

Cl2 + light

C8H10O

NaOH

heat

Cl2 + AlCl3

C8H8ClO2N

HNO3 +

H2SO4

55˚C

KMnO4

+ OH–

+ heat

then H+

C10H10O4

CH3OH +conc. H2SO4

heat

[6]

[Total: 6]



13


BLANK PAGE



14

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

Section B


8 The molecule that contains the genetic information for an individual organism is called deoxyribonucleic acid, DNA.

(a) The diagram shows part of a DNA molecule. Study the diagram and identify the blocks labelled J, K, L and M as accurately as you can.

J cytosine K

adenine M

L

block letter identity

J

K

L

M [3]

(b) The DNA molecule is formed from two polymer strands. What stops these strands from separating from each other?

..........................................................................................................................................

...................................................................................................................................... [2]



15


ForExaminer’s

Use

(c) List three differences between the structures of DNA and RNA.

1. ......................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

2. ......................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

3. ......................................................................................................................................

..........................................................................................................................................

.......................................................................................................................................... [3]

(d) Outline the different roles of mRNA and tRNA in the processes of transcription and translation.

mRNA ..............................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

tRNA ................................................................................................................................

..........................................................................................................................................

.......................................................................................................................................... [2]

[Total: 10]



16

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

9 A range of modern analytical techniques has made the identification of molecules, and atoms in compounds, much more rapid than traditional laboratory analysis.

(a) One instrumental technique is NMR spectroscopy, which uses the fact that under certain conditions protons can exist in two different energy states.

Explain how these different energy states arise.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(b) When methanol, CH3OH, is examined using NMR spectroscopy, it absorbs at two different frequencies. Explain why, and predict the relative areas of the two peaks.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(c) The NMR spectrum below is that of one of three possible isomers of molecular formula C3H6O2.

1 09 8 7 6 5chemical shift, δ / ppm

A B

4 3 2 1 0



17


ForExaminer’s

Use

The compound could be propanoic acid, methyl ethanoate or ethyl methanoate.

(i) In the boxes provided, draw the structures of the three compounds.

propanoic acid methyl ethanoate ethyl methanoate

(ii) Explain which compound produced the spectrum shown, indicating which protons are responsible for each of the peaks A and B.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) The NMR spectrum of another of the compounds has a peak at δ11.0. State which compound this would be, and identify the proton(s) responsible for this

peak.

compound ..................................................

proton(s) .................................................. [4]

(d) X-ray crystallography is a technique used to identify the relative positions of atoms in a crystal of a compound.

(i) What further information about organic macromolecules can be deduced by the use of X-ray crystallography?

..................................................................................................................................

..................................................................................................................................

(ii) Which atoms cannot be located by X-ray crystallography?

........................................................ [2]

[Total: 10]



18

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

10 The nature and variety of drugs that are available to treat diseases or life-threatening conditions has never been greater. At the same time, we are much better able to deliver drugs to their targets in the body.

(a) Some drugs have to be given by injection, rather than by mouth. Name a functional group in a drug molecule that might be broken down by the acid in

the stomach.

...................................................................................................................................... [1]

(b) The anti-cancer drug Taxol could be broken down if taken by mouth.

O

O O

O

O

O

O

O

O

O

OH

O

NH

HO

OHH

Taxol

Circle two bonds, each in a different functional group, that could be hydrolysed in the digestive system. [2]



19


ForExaminer’s

Use

(c) One way of protecting drug molecules that are taken by mouth is to enclose them in liposomes. These are artificially created spheres made from phospholipids which have an ionic phosphate ‘head’ and two hydrocarbon ‘tails’.

BA C

phospholipid

(i) State in which area of the liposome, A, B or C, each of the following types of drug would be carried.

a hydrophilic drug .........................

a hydrophobic drug .......................

(ii) For the remaining position, A, B or C, explain why this would not be a suitable area for carrying a drug.

..................................................................................................................................

..................................................................................................................................[3]

(d) One way of carrying drugs in the bloodstream is to attach them by a chemical bond to a polymer. One such polymer is polyethylene glycol or PEG.

HO – (CH2 – CH2 – O)n – H

(i) Where would a drug be attached to a molecule of PEG?

..................................................................................................................................

(ii) Suggest why a liposome can carry more drug molecules than a molecule of PEG.

..................................................................................................................................

..................................................................................................................................[2]



20

9701/41/M/J/10© UCLES 2010

ForExaminer’s

Use

(e) Better-targeted delivery of drugs allows smaller amounts to be used, which brings significant advantages.

Suggest two advantages of using smaller drug doses.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

[Total: 10]






DC (SM/CGW) 22690/3© UCLES 2010 [Turn over

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Level







*4308885825*

CHEMISTRY 9701/42


1 hour 45 minutes




1

2

3

4

5

6

7

8

Total



2

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

Section A


1 Phenacyl chloride has been used as a component of some tear gases. Its lachrymatory and irritant properties are due to it reacting with water inside body tissues to produce hydrochloric acid.

It undergoes a nucleophilic substitution reaction with NaOH(aq).

O

+ OH–

phenacyl chloride

+

Cl

(a) Write the formulae of the products of this reaction in the two boxes above. [2]

When the rate of this reaction was measured at various concentrations of the two reagents, the following results were obtained.

experiment number [phenacyl chloride] [NaOH] relative rate

1 0.020 0.10 1.0

2 0.030 0.10 1.5

3 0.025 0.20 2.5

(b) (i) What is meant by the term order of reaction?

..................................................................................................................................

(ii) Use the above data to deduce the order with respect to each reactant. Explain your reasoning.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Write the overall rate equation for the reaction.

..................................................................................................................................



3

© UCLES 2010 [Turn over9701/42/M/J/10

ForExaminer’s

Use

(iv) Describe the mechanism for this reaction that is consistent with your overall rate equation.

You should show all intermediates and/or transition states and partial charges, and you should represent the movements of electron pairs by curly arrows.

[7]

(c) (i) Describe an experiment that would show that CH3COCl reacts with water at a much faster rate than phenacyl chloride. Include the reagents you would use, and the observations you would make with each chloride.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Suggest an explanation for this difference in reactivity.

..................................................................................................................................

..................................................................................................................................[4]

[Total: 13]



4

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

2 (a) Describe and explain how the solubilities of the sulfates of the Group II elements vary down the group.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(b) The following table lists some enthalpy changes for magnesium and strontium compounds.

enthalpy change value for magnesium/ kJ mol–1

value for strontium/ kJ mol–1

lattice enthalpy of M (OH)2 –2993 –2467

enthalpy change of hydration of M 2+(g) –1890 –1414

enthalpy change of hydration of OH–(g) –550 –550

(i) Use the above data to calculate values of ΔH osolution for Mg(OH)2 and for Sr(OH)2.

Mg(OH)2 ...................................................................................................................

..................................................................................................................................

ΔH osolution = ..................................... kJ mol–1

Sr(OH)2 ....................................................................................................................

..................................................................................................................................

ΔH osolution = ..................................... kJ mol–1

(ii) Use your results in (i) to suggest whether Sr(OH)2 is more or less soluble in water than is Mg(OH)2. State any assumptions you make.

..................................................................................................................................

..................................................................................................................................

(iii) Suggest whether Sr(OH)2 would be more or less soluble in hot water than in cold. Explain your reasoning.

..................................................................................................................................

..................................................................................................................................[5]



5


ForExaminer’s

Use

(c) Calcium hydroxide, Ca(OH)2, is slightly soluble in water.

(i) Write an expression for Ksp for calcium hydroxide, and state its units.

Ksp = units ............................................

(ii) 25.0 cm3 of a saturated solution of Ca(OH)2 required 21.0 cm3 of 0.0500 mol dm–3 HCl for complete neutralisation.

Calculate the [OH–(aq)] and the [Ca2+(aq)] in the saturated solution, and hence calculate a value for Ksp.

[OH–(aq)] = .................................

[Ca2+(aq)] = ................................

Ksp = .........................................................................................

(iii) How would the solubility of Ca(OH)2 in 0.1 mol dm–3 NaOH compare with that in water?

Explain your answer.

..................................................................................................................................

..................................................................................................................................[6]

[Total: 14]



6

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

3 (a) Fluorine is much more electronegative than both silicon and sulfur, but whereas the molecule of SF4 has an overall dipole, that of SiF4 has none.

Suggest a reason for this difference.

..........................................................................................................................................

...................................................................................................................................... [1]

(b) Predict whether or not the following molecules will have an overall dipole. Place a tick in the appropriate column.

compound molecule has anoverall dipole

molecule does not havean overall dipole

BCl 3

PCl 3

CCl 4

SF6

[2]

(c) Boron and silicon are two elements adjacent to carbon in the periodic table. CCl4 does not react with water, whereas BCl 3 and SiCl4 do react.

(i) Suggest a reason for this difference in reactivity.

..................................................................................................................................

..................................................................................................................................

(ii) Construct equations showing the reaction of these two chlorides with an excess of water.

BCl 3 .........................................................................................................................

SiCl4 .........................................................................................................................[3]



7


ForExaminer’s

Use

(d) When reacted with a small quantity of water, SiCl 4 produces an oxychloride X, SixCl yOz. The mass spectrum of X shows peaks at mass numbers of 133, 149, 247, 263 and 396. (You should assume that the species responsible for all these peaks contain the 16O,

the 35Cl and the 28Si isotopes only.)

(i) Use these data to deduce the molecular formula of X.

molecular formula .........................................

(ii) Suggest the structures of the fragments responsible for the peaks at the following mass numbers.

mass number structure

133

247

263

(iii) Hence suggest the displayed formula of X.

[5]

[Total: 11]



8

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

4 (a) Complete the electronic structures of the Cr3+ and Mn2+ ions.

Cr3+ 1s22s22p6 .............

Mn2+ 1s22s22p6 .............[2]

(b) (i) Describe what observations you would make when dilute KMnO4(aq) is added slowly and with shaking to an acidified solution of FeSO4(aq) until the KMnO4 is in a large excess.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Construct an ionic equation for the reaction that occurs.

..................................................................................................................................[4]

(c) By selecting relevant E o data from the Data Booklet explain why acidified solutions of Fe2+(aq) are relatively stable to oxidation by air, whereas a freshly prepared precipitate of Fe(OH)2 is readily oxidised to Fe(OH)3 under alkaline conditions.

relevant E o values and half equations

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

explanation

..........................................................................................................................................

..........................................................................................................................................[4]



9


ForExaminer’s

Use

(d) Predict the organic products of the following reactions and draw their structures in the boxes below. You may use structural or skeletal formulae as you wish.

hot conc.MnO4

– + H+

hot conc.MnO4

– + H+

hotCr2O7

2– + H+

OH

OH

[4]

(e) KMnO4 and K2Cr2O7 are the reagents that can be used to carry out the following transformation.

E

I IICHO

OH

(i) Draw the structure of intermediate E in the box above.

(ii) Suggest reagents and conditions for the following.

reaction I ...................................................................................................................

reaction II ..................................................................................................................[3]

[Total: 17]



10

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

5 (a) (i) Briefly explain why the benzene molecule is planar.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Briefly explain why all the carbon-carbon bonds in benzene are the same length.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[2]

(b) Benzene can be nitrated by warming it with a mixture of concentrated sulfuric andnitric acids.

(i) By means of an equation, illustrate the initial role of the sulfuric acid in this reaction.

..................................................................................................................................

(ii) Name the type of reaction and describe the mechanism for the nitration reaction, including curly arrows showing the movement of electrons and all charges.

type of reaction .........................................................................................................

mechanism

[4]

(c) State the reagents and conditions needed to convert benzene into chlorobenzene.

...................................................................................................................................... [1]



11


ForExaminer’s

Use

(d) Nitrobenzene undergoes further substitution considerably more slowly than chlorobenzene. In nitrobenzene the incoming group joins to the benzene ring in the 3-position, whereas

in chlorobenzene the incoming group joins to the benzene ring in the 4-position.

(i) Use these ideas to suggest the structures of the intermediate compounds Y and Z in the following synthesis of 4-chlorophenylamine.

I II

ZY

III

NH2

Cl

(ii) Suggest the reagents and conditions needed for reaction III in the above synthesis.

..................................................................................................................................

..................................................................................................................................

(iii) Suggest the structural formulae of the products A, B, C and D of the following reactions. If no reaction occurs write “no reaction” in the relevant box.

BA

DC

NH2

Br2(aq)

OH–(aq) NaNO2+ HCl

CH3COCl

Cl

[8]

[Total: 15]



12

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

Section B


6 Human hair and silk both consist of proteins. Proteins are described as having three major levels of structure: primary, secondary and tertiary.

(a) Outline what is meant by the terms primary structure and tertiary structure of a protein.

primary structure ..............................................................................................................

..........................................................................................................................................

..........................................................................................................................................

tertiary structure ..............................................................................................................

..........................................................................................................................................

..........................................................................................................................................[2]

(b) In hair, the secondary structure consists of α-helices which are cross-linked bydisulfide bonds. The amino acid responsible for this cross-linking is cysteine, H2NCH(CH2SH)CO2H.

(i) Show by means of a diagram how the disulfide cross-links are formed.

(ii) What type of reaction is this?

..................................................................................................................................



13


ForExaminer’s

Use

(iii) State three other interactions that stabilise the tertiary structure of proteins.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

(c) The β-pleated sheet is a different form of secondary structure found in proteins, such as those in silk.

(i) What type of bonding is responsible for stabilising the β-pleated sheet in silk?

..................................................................................................................................

(ii) On the diagram below, draw a second polypeptide strand and show how bonds would be formed that stabilise this β-pleated sheet.

N

H

CH CH

CHCH

R

O R H O R

C

N

H O R H O

C

N C

N C

[3]

(d) The cysteine-containing protein in hair is called α-keratin. A similar sequence of amino acids can produce β-keratin proteins found in the scales, claws and shells of reptiles such as tortoises. In β-keratin the secondary structure of the protein is in the form of a β-pleated sheet.

Suggest what makes the β-pleated sheet in β-keratin so much less flexible than the β-pleated sheet in silk.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [1]

[Total: 10]



14

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

7 A mixture of amino acids may be separated using electrophoresis. A typical practical set-up is shown in the diagram.

d.c. power supply

+ –glass slides

filter paper soaked in buffer solutionamino acid mixture placed here

electrolyte

(a) When the power supply is switched on, some amino acids may not move, but remain stationary. Suggest an explanation for this observation.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(b) The amino acid glycine has the formula H2NCH2CO2H. Identify the species formed on the filter paper if glycine moves to the left (positive) end of the filter paper.

.................................................................. [1]

(c) The following result was obtained from another electrophoresis. What can be deduced about the relative sizes of, and charges on, the amino acid species A, B and C?

A

+ –

B

mixture placed here

C

amino acid relative size charge

A

B

C

[3]



15


ForExaminer’s

Use

(d) The sequence of amino acids in a polypeptide may be determined by partial hydrolysis of the chain into smaller pieces, often tripeptides.

(i) Following such a partial hydrolysis, the following tripeptides were obtained from a given polypeptide.

ala-gly-asp gly-ala-gly lys-val-ser ser-ala-gly val-ser-ala

Given that the N-terminal amino acid is lysine (lys) suggest the amino acid sequence of the shortest polypeptide that would give the above tripeptides.

..................................................................................................................................

The structural formulae of the amino acids in the polypeptide are given below.

abbreviation amino acid structural formula

ala alanine H2NCH(CH3)CO2H

asp aspartic acid H2NCH(CH2CO2H)CO2H

gly glycine H2NCH2CO2H

lys lysine H2NCH(CH2CH2CH2CH2NH2)CO2H

ser serine H2NCH(CH2OH)CO2H

val valine H2NCH(CH(CH3)2)CO2H

(ii) Which of the tripeptides in (i) has the lowest Mr?

..........................................................................

(iii) Select one amino acid from those listed in the table which contains an ionicside-chain at pH 8.

..........................................................................

[4]

[Total: 10]



16

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

8 The design and development of batteries has been a major research area in recent years.

(a) Lead-acid batteries, used in cars, are made up of a number of rechargeable cells in series, and were first developed in 1860. They have the disadvantage of a relatively high mass compared to the energy stored. During discharge, the electrode reactions in the cells of these batteries are as follows.

I Pb + SO42– PbSO4 + 2e–

II PbO2 + 4H+ + SO42– + 2e– PbSO4 + 2H2O

State which of these reactions occurs at the positive electrode in a lead-acid cell during discharge, explaining your answer.

..........................................................................................................................................

...................................................................................................................................... [1]

(b) Use the Data Booklet and the equations I and II above to calculate the voltage produced by a lead-acid cell under standard conditions.

[2]

(c) Nickel-metal hydride batteries were developed in the 1980s and have become increasingly common particularly for small devices such as mobile phones and digital cameras that need near-constant sources of electrical energy. These cells use nickel oxohydroxide (NiO(OH)) as one electrode and a hydrogen-absorbing alloy such as LiNi5 as the other electrode.

One reaction that takes place in these batteries is

NiO(OH) + H2O + e– Ni(OH)2 + OH–

(i) State the oxidation state of nickel in NiO(OH). .....................

(ii) Suggest a likely advantage of these batteries compared with lead-acid batteries.

..................................................................................................................................

..................................................................................................................................[2]



17

© UCLES 2010 9701/42/M/J/10

ForExaminer’s

Use

(d) Hydrogen fuel cells have been suggested as the next major advance in electrically powered vehicles. In these fuel cells hydrogen is oxidized to produce water, using a catalyst and inert electrodes.

(i) Suggest a material for the electrodes.

..........................................................................

(ii) Use your knowledge of hydrogen to suggest a disadvantage of these fuel cells in powering vehicles.

..................................................................................................................................

..................................................................................................................................[2]

(e) Many of the world’s countries are developing ways of recycling materials which are valuable or which require large amounts of energy to produce.

For each of the following recyclable materials, state whether recycling of this material is important in saving energy or in saving resources. Use your knowledge of chemistry to explain each choice.

glass ................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

steel .................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

plastics .............................................................................................................................

..........................................................................................................................................

..........................................................................................................................................[3]

[Total: 10]



18

9701/42/M/J/10© UCLES 2010

BLANK PAGE



19

9701/42/M/J/10© UCLES 2010

BLANK PAGE



20

9701/42/M/J/10© UCLES 2010

BLANK PAGE





TIME 1 hour

INSTRUCTIONS TO CANDIDATES

Write your name, Centre number and candidate number in the spaces at the top of this page.

Answer all questions.

Write your answers in the spaces provided on the question paper.

INFORMATION FOR CANDIDATES

The number of marks is given in brackets [ ] at the end of each question or part question.

You may lose marks if you do not show your working or if you do not use appropriate units.

CAMBRIDGE INTERNATIONAL EXAMINATIONS

General Certificate of Education Advanced Level

CHEMISTRY 9701/4PAPER 4

OCTOBER/NOVEMBER SESSION 20021 hour

Candidates answer on the question paper.Additional materials:

Data Booklet.

This question paper consists of 11 printed pages and 1 blank page.

(NH/CG) S14878/4© CIE 2002 [Turn over


3

2

1

4

TOTAL

6

5

CandidateCentre Number Number

Candidate Name



2

9701/4 O/N/02


1 (a) The following diagram shows the apparatus needed to measure the standard electrodepotential of copper. In the spaces below, identify or describe what the three letters A–Crepresent.

A .......................................................................................................................................

B .......................................................................................................................................

C .......................................................................................................................................[3]

(b) A student wishes to measure the standard electrode potential of the Fe3+/Fe2+

electrode. In the space below, draw and label the set-up for the right-hand beakerthat would replace the one shown in the diagram above.

[2]

(c) Predict how the E of the Fe3+/Fe2+ electrode would vary as

(i) the [Fe3+] is increased,

...................................................................................................................................

(ii) the [Fe2+] is increased.

...................................................................................................................................[1]

H2, 1 atm, 298 K

platinum black

copper

1.0 mol dm–3

CuSO4(aq)

C

A

B

ForExaminer’s

Use



3

9701/4 O/N/02 [Turn over

(d) An aqueous solution of iron(III) chloride is used to dissolve the excess of copper metalfrom printed-circuit boards.

Use the half-equations and E o– values in the Data Booklet to

(i) write an equation for this reaction,

...................................................................................................................................

(ii) calculate the E o–cell for the reaction.

...................................................................................................................................[2]

(e) The solution resulting from dissolving the copper from a small printed-circuit board wasacidified and titrated with 0.0200 mol dm–3 KMnO4. A volume of 75.0 cm3 was requiredfor the end point.

The equation for the titration reaction is as follows.

5Fe2+ + MnO4– + 8H+ → 5Fe3+ + Mn2+ + 4H2O

Calculate

(i) the number of moles of Fe2+ in the solution,

(ii) the mass of copper that had dissolved from the printed-circuit board.

[4]

[Total: 12]

ForExaminer’s

Use



4

9701/4 O/N/02

2 (a) Write an equation to represent the lattice energy of sodium oxide, Na2O.

......................................................................................................................................[1]

(b) The Born-Haber cycle shown may be used to calculate the lattice energy of sodiumoxide.

(i) In the spaces below, identify the species A and B in the cycle, including theappropriate state symbols.

species A ................................... species B ...................................

(ii) Identify the enthalpy changes labelled by the numbers 1 to 4 in the cycle.

1 ................................................................................................................................

2 ................................................................................................................................

3 ................................................................................................................................

4 ................................................................................................................................[3]

2Na+(g) + O2–(g)

2Na+(g) + B

2

1

3

4

2Na+(g) + 1/2O2(g)

A + 1/2O2(g)

2Na(s) + 1/2O2(g)

2∆Hat(Na)

Na2O(s)

∆Hat(oxygen)

ForExaminer’s

Use



5


(c) Use your cycle, the following data, and further data from the Data Booklet to calculate avalue for the lattice energy of sodium oxide.

Data: enthalpy change of atomisation for Na(s) +107 kJ mol–1

first electron affinity of oxygen –141 kJ mol–1

second electron affinity of oxygen +798 kJ mol–1

enthalpy change of formation of Na2O(s) –414 kJ mol–1

enthalpy change of atomisation for oxygen = half the bond energy for O2.

[3]

(d) (i) How would you expect the magnitude of lattice energy of magnesium oxide tocompare with that of sodium oxide? Explain your reasoning.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) State a use of magnesium oxide, and explain how the use relates to your answer inpart (d) (i).

...................................................................................................................................

...................................................................................................................................[4]

[Total: 11]

ForExaminer’s

Use



6

9701/4 O/N/02

3 (a) (i) On the following axes, sketch the variation in melting points of the elements inGoup IV.

[2]

(ii) Explain how this variation in melting point is related to the structure and bonding ofthe elements.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[2]

(b) CCl4 and SiCl4 behave differently with water.

(i) Describe the reaction (if any) of CCl4 with water.

...................................................................................................................................

(ii) Describe the reaction (if any) of SiCl4 with water.

...................................................................................................................................

(iii) Write equations for any reactions that occur.

...................................................................................................................................

...................................................................................................................................

(iv) Explain why these two chlorides differ in their behaviour with water.

...................................................................................................................................

...................................................................................................................................[4]

[Total: 8]

C Si Ge Sn Pb

meltingpoint

ForExaminer’s

Use



7


4 (a) The melting point and density of a typical transition element such as iron differ fromthose of a typical s-block element such as calcium. Describe and explain thesedifferences.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) Suggest a reason why iron forms compounds containing Fe3+ ions as well ascompounds containing Fe2+ ions, whereas calcium only forms compounds containingCa2+ ions.

..........................................................................................................................................

......................................................................................................................................[1]

(c) An important ore of iron is siderite, iron(II) carbonate. The first step in converting it intoiron is to heat it in air. When heated in air, both calcium carbonate and iron(II) carbonatedecompose, but in different ways.

(i) Write an equation to represent the thermal decomposition of calcium carbonate.

...................................................................................................................................

(ii) When siderite is heated in air, carbon dioxide is evolved and iron(III) oxide, Fe2O3,is left.

Construct an equation for this reaction.

...................................................................................................................................

(iii) Calculate how much iron(III) oxide can be obtained by heating 10 tonnes ofsiderite.

...................................................................................................................................

...................................................................................................................................[4]

[Total: 8]

ForExaminer’s

Use



8

9701/4 O/N/02

5 Benzene can be converted into nitrobenzene by a nitration reaction.

(a) State the reagents and conditions necessary to carry out this reaction.

..........................................................................................................................................

......................................................................................................................................[2]

(b) What type of reaction mechanism is this?

......................................................................................................................................[1]

(c) The reaction proceeds via two steps:

(i) Draw the structure of the intermediate Y in the box.

(ii) Identify the cation X+..................................................................................................

(iii) Identify the cation Z+..................................................................................................

(iv) Write an equation to show how X+ is produced from the reagents.

...................................................................................................................................[5]

NO2+ X+

Y

+ Z+

NO2

ForExaminer’s

Use



9


(d) Some aromatic poly-nitro compounds are used in perfumes as artificial musks. Anexample is ‘Baur musk’.

(i) Draw the structural formula of the hydrocarbon that could be nitrated in order toproduce Baur musk.

(ii) Suggest the structural formula of the compound formed by reacting Baur musk withan excess of tin and concentrated hydrochloric acid.

[2]

[Total: 10]

NO2

CH3

NO2

C(CH3)3

O2N

Baur musk

ForExaminer’s

Use



10

9701/4 O/N/02

6 Amides can be made by reacting amines with acyl chlorides, as in the example below.

CH3CH2COCl + H2NCH2CH2CH3 → CH3CH2CONHCH2CH2CH3 + HCl

(a) What type of reaction mechanism is this?

......................................................................................................................................[1]

(b) What compound could CH3CH2COCl be made from, and what reagent would you use?

..........................................................................................................................................

......................................................................................................................................[2]

(c) The amine CH3CH2CH2NH2 can be made from CH3CH2Br in two steps.

(i) Draw the structural formula of the intermediate in the box provided.

...................................................................................................................................

(ii) State the reagents and conditions for step I.

...................................................................................................................................

(iii) State the reagents and conditions for step II.

...................................................................................................................................[4]

CH3CH2BrI II

CH3CH2CH2NH2

ForExaminer’s

Use



11

9701/4 O/N/02

(d) Kevlar is a low weight, high strength polyamide used as a reinforcement in car tyres,aircraft wings and in bullet-proof vests. A portion of its chain is shown below.

(i) What type of polymerisation produces Kevlar?

...................................................................................................................................

(ii) Draw the structural formulae of the monomers from which Kevlar is made.

(iii) Suggest a reason why Kevlar is much stronger than most other polyamides.

...................................................................................................................................

(iv) What reaction conditions are needed to break the amide bonds in Kevlar?

...................................................................................................................................[4]

[Total: 11]

NH–CONH CO–NH NH

ForExaminer’s

Use



12

9701/4 O/N/02

BLANK PAGE




SP (SLC/SLC) S33029/5© UCLES 2003 [Turn over

CAMBRIDGE INTERNATIONAL EXAMINATIONS General Certificate of Education


CHEMISTRY 9701/04

Paper 4 Structured Questions A2 CoreOctober/November 2003

1 hourCandidates answer on the Question Paper.Additional Materials: Data Booklet


Write your name, Centre number and candidate number in the spaces at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.





3

2

1

4

TOTAL

6

5



2

9701/4/O/N/03

1 The reaction between iodine and propanone is catalysed by hydrogen ions.

The reaction is found to be first order with respect to [CH3COCH3] and with respect to [H+],and zero order with respect to [I2].

(a) What do you understand by the term order of reaction?

..........................................................................................................................................

......................................................................................................................................[1]

(b) Construct a rate equation for the reaction.

......................................................................................................................................[1]

The following sketches show three ways in which the concentration of reagents might varyduring the reaction.

(c) Which of the above graphs correctly describes how the concentration of reactantchanges with time for

(i) the propanone concentration, _____________________

(ii) the iodine concentration? _____________________[2]

[reactant]

time

A

[reactant]

time

B

[reactant]

time

C

H+

CH3COCH3 + I2 → CH3COCH2I + HI

ForExaminer’s

Use



3

9701/4/O/N/03 [Turn over

(d) When carried out in 0.1 mol dm–3 HCl solution, the rate was found to be0.002 mol dm–3 s–1. Predict the rate of reaction in 0.2 mol dm–3 HCl and in0.3 mol dm–3 HCl solution. Plot your figures on the following graph, and draw a linethrough the points.

[2]

(e) Only one of the following outline reaction mechanisms is consistent with the observedkinetics.

A � I2 + H+ → intermediate [slow]intermediate + CH3COCH3 → products [fast]

B � CH3COCH3 + H+ → intermediate [slow]intermediate + I2 → products [fast]

C � CH3COCH3 + H+ → intermediate [fast]intermediate + I2 → products [slow]

D � CH3COCH3 + I2→ intermediate [slow]

intermediate + H+ → products [fast]

Decide which mechanism is consistent, explaining the reasons for your choice.

Mechanism letter (A, B, C or D) _____________________

Reasons

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

00

0.002

0.004

0.006rate /mol dm–3 s–1

[HCl] /mol dm–3

0.008

0.010

0.1 0.2 0.3

ForExaminer’s

Use



4

9701/4/O/N/03

(f) When the starting concentrations of propanone, iodine and H+ were 0.20 mol dm–3,0.01 mol dm–3 and 0.5 mol dm–3 respectively, the rate of decrease of [I2] was found tobe 3.3 x 10–6 mol dm–3 s–1.

(i) Suggest a method you could use to measure [I2].

...................................................................................................................................

(ii) Use these figures and your rate equation in part (b) to calculate a value for the rateconstant k.

...................................................................................................................................

(iii) What are the units of k?

...................................................................................................................................[3]

[Total : 12]

2 (a) Methanoic acid, HCO2H, is a weak acid, with Ka = 1.77 x 10–4 mol dm–3.

(i) Write an expression for the Ka of methanoic acid.

...................................................................................................................................

(ii) Use your expression to calculate the [H+] in a 0.0500 mol dm–3

solution ofmethanoic acid.

...................................................................................................................................

(iii) Calculate the percentage of HCO2H molecules that are ionised in this solution.

(iv) Calculate the pH of this solution.

...................................................................................................................................[4]

ForExaminer’s

Use



5


(b) Calculate the pH of a 0.0500 mol dm–3 solution of the strong acid HCl.

......................................................................................................................................[1]

(c) Both HCO2H and HCl react with powdered magnesium metal, giving off hydrogen gas.For a fixed amount of magnesium, the rate equation for the reaction is as follows.

rate = k [H+(aq)]

(i) Write an equation for the reaction between HCO2H and Mg.

...................................................................................................................................

When 20.0 cm3 of a 0.0500 mol dm–3 solution of either acid is reacted with an excess ofpowdered magnesium, the same volume of hydrogen is given off, but the methanoicacid solution reacts much more slowly than the hydrochloric acid.

(ii) Calculate the volume of hydrogen given off.

...................................................................................................................................

(iii) Explain why the hydrogen is evolved more slowly from the methanoic acid solution.

...................................................................................................................................

...................................................................................................................................

(iv) Explain why, eventually, the methanoic acid solution produces just as muchhydrogen as the hydrochloric acid solution.

...................................................................................................................................

...................................................................................................................................

...............................................................................................................................[5]

[Total : 10]

ForExaminer’s

Use



6

9701/4/O/N/03

3 Potassium manganate(VII) and potassium dichromate(VI) are both used as oxidisingagents in acidic solution.

(a) Using data from the Data Booklet, write either ionic or full equations for the reactionbetween

(i) KMnO4 and FeSO4 in dilute H2SO4,

(ii) K2Cr2O7 and SO2 in dilute H2SO4.

[3]

(b) KMnO4 is often used in titrations to estimate reducing agents. It is added from a buretteto a solution of the reducing agent.

(i) What colour is KMnO4 solution?

...................................................................................................................................

(ii) How is the end point in the titration recognised?

...................................................................................................................................

(iii) A solution of 0.010 mol dm–3 KMnO4 was used to estimate the amount of FeSO4 inan iron dietary supplement tablet. The tablet was crushed under dilute H2SO4 andthe KMnO4 solution was added from the burette. It was found that 14.00 cm3 wererequired.

Calculate the mass of FeSO4 in the tablet.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[5]

ForExaminer’s

Use



7


(c) Patients are prescribed iron dietary supplement tablets to cure anaemia, which is adeficiency of haemoglobin in the blood.

(i) Describe the function of haemoglobin, and how the iron atoms it contains carry outthat function.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(ii) Explain why even a small amount of carbon monoxide in the bloodstream ispoisonous.

...................................................................................................................................

...................................................................................................................................[3]

[Total : 11]

ForExaminer’s

Use



8

9701/4/O/N/03

4 Ethyl 4-hydroxybenzoate, E, is a permitted food preservative.

(a) Name two functional groups in E.

..........................................................................................................................................

......................................................................................................................................[2]

(b) Draw the structures of the compounds formed when E reacts with

(i) sodium metal,

(ii) NaOH(aq) under reflux,

(iii) Br2(aq).

[4]

HO CO2C2H5

E

ForExaminer’s

Use



9


(c) Compounds F and G are isomers of E.

(i) Suggest the order of acid strength of E, F and G.

...................................................................................................................................

...................................................................................................................................

(ii) Based on their relative acidities, suggest how samples of E, F and G could bedistinguished from each other by the use of NaOH(aq) and Na2CO3(aq).

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[3]

[Total : 9]

HOCH2 CO2CH3

F

CH3CH2O CO2H

G

ForExaminer’s

Use



10

9701/4/O/N/03

5 The amino acid alanine, K, can be obtained from 2-hydroxypropanoic acid, H, by thefollowing route.

(a) Suggest a test you could use to distinguish H from its isomer 3-hydroxypropanoic acid, L.

HOCH2CH2CO2HL

reagents ...........................................................................................................................

observation with H ............................................................................................................

observation with L ........................................................................................................[2]

(b) How would the acidity of chloropropanoic acid, J, compare with that of propanoic acid?Briefly explain your answer.

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]

(c) Alanine reacts with both acids and bases.

Write an equation for the reaction between alanine and sodium hydroxide, drawing thedisplayed formula of the organic product.

[2]

(d) In solution, alanine exists as a zwitterion. Draw the structure of this ion.

[1]

I IICH3CH(OH)CO2H → CH3CHClCO2H → CH3CH(NH2)CO2H

H J K

ForExaminer’s

Use



11


(e) Alanine is one of about 20 amino acids that make up proteins.

(i) What type of bond joins amino acids together in proteins?

...................................................................................................................................

(ii) Draw the displayed formula of the compound formed when two alanine moleculesare joined by this bond.

[2]

(f) An excess of benzoic acid in the body (present as a preservative in many foodstuffs, orformed by oxidation of aromatic compounds present in food) is excreted as hippuricacid, M.

(i) Suggest a reagent that could be reacted with glycine in the laboratory to formhippuric acid.

...................................................................................................................................

(ii) Suggest the reagents and conditions needed to re-form glycine from hippuric acid.

...................................................................................................................................

...................................................................................................................................[3]

[Total : 12]

CONHCH2CO2H

M

ForExaminer’s

Use



12

9701/4/O/N/03

6 Many millions of tonnes of limestone, CaCO3, are quarried each year for use in the steelindustries of the world, and in agriculture. For use in agriculture, the limestone is oftendecomposed by heating it in limekilns, and then adding water.

(a) Write balanced equations representing the following two processes.

(i) heating limestone

...................................................................................................................................

(ii) then adding water

...................................................................................................................................[2]

(b) Describe the agricultural use of the product of this process.

..........................................................................................................................................

..........................................................................................................................................[1]

(c) Describe and explain the trend observed in the thermal stabilities of the carbonates of Group II.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................[3]

[Total : 6]

ForExaminer’s

Use




SPA (SJF3046/GR) S61559/4© UCLES 2004 [Turn over



CHEMISTRY 9701/04




Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs or rough working.You may use a calculator.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.




3

2

1


4

5

6

7

Total



2

9701/04/O/N04

1 Sulphuric acid is a strong dibasic acid, which ionises in solution as follows.

H2SO4(aq) 2H+(aq) + SO42–(aq)

(a) The organic base guanidine contains carbon, nitrogen and hydrogen. Its reaction withacids can be represented as follows.

B(aq) + H+ (aq) BH+(aq)

where B represents the molecule of guanidine.

When a 25.0 cm3 sample of dilute sulphuric acid was titrated against a solution ofguanidine, the following titration curve was obtained.

Use this curve to answer the following questions.

(i) Is guanidine a strong or a weak base? Explain your answer.

...................................................................................................................................

...................................................................................................................................

(ii) The pH at the start of the titration was 0.70. Calculate the [H+], and hence theconcentration of sulphuric acid, at the start of the titration.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

00

7

pH

14

10 20 30 40 50 60

Volume of guanidine added / cm3

70

ForExaminer’s

Use

© UCLES 2004



3

9701/04/O/N04 [Turn over

(iii) Calculate the concentration of guanidine in the solution in mol dm–3.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iv) The guanidine solution contained 8.68 g of the base per dm3. Use your answer to(iii) calculate the Mr of guanidine.

.............................................................................................................................. [6]

(b) One of the major industrial uses of sulphuric acid is to convert phosphate rock (calciumfluorophosphate(V)) into ‘superphosphate’ for use as a fertiliser. The process can berepresented by the following partially balanced equation.

2 Ca5(PO4)3F + 7H2SO4 → ....... CaSO4 + ....... Ca(H2PO4)2 + ....... HF‘superphosphate’

(i) Balance the above equation.

(ii) Use your balanced equation to calculate the mass of H2SO4 required tomanufacture 1.0 kg of superphosphate fertiliser.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

.............................................................................................................................. [4]

(c) Solutions of hydrogenphosphates make useful buffers for biochemical experiments.

H2PO4– HPO4

2– + H+

(i) Explain what is meant by the term buffer solution.

...................................................................................................................................

...................................................................................................................................

(ii) Calculate the pH of a buffer solution that contains 0.20 mol dm–3 NaH2PO4 and0.10 mol dm–3 Na2HPO4. [Ka (H2PO4

–) = 6.3 x 10–8 mol dm–3]

...................................................................................................................................

...................................................................................................................................

.............................................................................................................................. [3]

[Total: 13]

ForExaminer’s

Use

© UCLES 2004



4

9701/04/O/N04

2 The diagram shows a laboratory illustration of a simple hydrogen-oxygen fuel cell.

(a) Write the half equation for the reaction occurring at the left hand (oxygen) electrodewhen the cell operates.

..........................................................................................................................................

..................................................................................................................................... [1]

(b) State the polarity (+ or –) of the left hand (oxygen) electrode. ..................................... [1]

(c) Use the Data Booklet to calculate the voltage produced by this cell.

..................................................................................................................................... [1]

(d) Only a very small current can be drawn from this laboratory cell. Suggest one way inwhich it could be modified to enable a larger current to be drawn from it.

..........................................................................................................................................

..................................................................................................................................... [1]

(e) A fuel cell in an orbiting satellite is required to produce a current of 0.010 A for 400 days.Calculate the mass of hydrogen that will be needed.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

ForExaminer’s

Use

© UCLES 2004

salt bridge

inert electrodes

oxygen gas at1 atmosphere

hydrogen gas at1 atmosphere

solution ofhydrochloric acid:

[H3O+] = 1 mol dm-3

solution ofhydrochloric acid:

[H3O+] = 1 mol dm-3

V



5


(f) State one advantage, and one disadvantage of using fuel cells to power road vehiclescompared to hydrocarbon fuels such as petrol.

advantage: .......................................................................................................................

..........................................................................................................................................

disadvantage: ...................................................................................................................

..................................................................................................................................... [2]

[Total: 9]

3 Calcium sulphate is a major by-product of flue gas desulphurisation, which is an importantmethod of decreasing the emission of acid-rain gases from power stations. It is usedextensively in plaster and cement. Both magnesium sulphate and barium sulphate find usesin medicine.

Describe and explain the variation in the solubilities of the Group II sulphates in water.

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

..................................................................................................................................................

............................................................................................................................................. [4]

[Total: 4]

ForExaminer’s

Use

© UCLES 2004



6

9701/04/O/N04

4 (a) Explain what is meant by the term transition element.

..........................................................................................................................................

..................................................................................................................................... [1]

(b) (i) How do the atomic radii of the transition elements vary from chromium to copper?

...................................................................................................................................

(ii) Predict, with a reason, the variation in the densities of the transition elements fromchromium to copper.

...................................................................................................................................

.............................................................................................................................. [3]

(c) Complete the following electronic configuration of the Cu2+ ion.

1s22s22p63s23p6 [1]

(d) Copper ions in aqueous solution are pale blue, due to the formation of a complex ion.

(i) Explain what is meant by the term complex ion.

...................................................................................................................................

...................................................................................................................................

(ii) Draw the structure of the complex ion formed in a solution of Cu2+(aq).

[2]

ForExaminer’s

Use

© UCLES 2004



7


(e) When dilute aqueous ammonia is added to a solution of Cu2+(aq), the colour changesas a new complex ion is formed.

(i) State the colour of the new complex .........................................................................

(ii) Write an equation showing the formation of the new complex.

.............................................................................................................................. [2]

(f) When concentrated hydrochloric acid is added to a solution of Cu2+(aq), the colourchanges to yellow-green. On adding water, the colour returns to pale blue.

Suggest an explanation for these changes.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

[Total: 12]

ForExaminer’s

Use

© UCLES 2004



8

9701/04/O/N04

5 This question is concerned with organochlorine compounds.

(a) State the conditions needed to produce the two compounds A and B.

(i) conditions for reaction I

...................................................................................................................................

(ii) conditions for reaction II

.............................................................................................................................. [2]

(b) State the reagent needed to carry out the following reaction.

reagent for reaction III: ................................................................................................. [1]

CO2H COCl

reaction III

C

CH3 CH3 CH2Cl

reaction I reaction II

Cl

Cl2 Cl2

A B

ForExaminer’s

Use

© UCLES 2004



9


(c) The three chloro-compounds A, B and C vary in their ease of hydrolysis.

(i) Place a tick in the box corresponding to the correct relative rates of hydrolysis. [the symbol ‘>’ means ‘faster than’]

(ii) Suggest an explanation for these differences in reactivity.

...................................................................................................................................

...................................................................................................................................

.............................................................................................................................. [3]

ForExaminer’s

Use

© UCLES 2004

A > B > C

A > C > B

B > A > C

B > C > A

C > B > A

C > A > B

place onetick only inthis column



10

9701/04/O/N04

(d) Draw the structural formulae of the organic products of the following reactions ofcompound C.

[3]

[Total: 9]

COCl

OH in NaOH (aq)

C

CH3NH2

H2O

ForExaminer’s

Use

© UCLES 2004



11


6 Compounds D and E are both ketones.

CH3CH2COCH2CH3 CH3CH2CH2COCH3

D E

(a) State which one of these compound reacts with alkaline aqueous iodine, and draw thestructural formulae of the products formed during this reactions.

(i) compound (D or E) ....................................................................................................

(ii) products

.............................................................................................................................. [3]

(b) The reduction of D with NaBH4 produces just one alcohol, but a similar reduction of Eproduces two isomers in equal amounts. Explain these observations, drawing structureswhere appropriate.

..........................................................................................................................................

..........................................................................................................................................

[3]

[Total: 6]

ForExaminer’s

Use

© UCLES 2004



12

9701/04/O/N04

7 Both phenol and phenylamine react similarly with aqueous bromine.

(a) State two observations you would make when these reactions take place.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(b) Describe a simple test-tube reaction you could use to distinguish between phenol andphenylamine.

..........................................................................................................................................

......................................................................................................................................[1]

(c) The compound 3-aminobenzoic acid can be prepared by the following series ofreactions.

Suggest suitable reagents and conditions for

reaction IV, .......................................................................................................................

reaction V, ........................................................................................................................

reaction VI. .................................................................................................................. [4]

[Total: 7]

ForExaminer’s

Use

© UCLES 2004

CH3 CO2H CO2H

NO2

CO2H

NH2

reaction IV reaction V reaction VI

Every reasonable effort has been made to trace all copyright holders where the publishers (i.e. UCLES) are aware that third-party material has been reproduced.The publishers would be pleased to hear from anyone whose rights they have unwittingly infringed.





SPA (MML 8078 3/04) S77894/4© UCLES 2005 [Turn over



CHEMISTRY 9701/04




Write your name, Centre number and candidate number in the spaces at the top of this page.Write in dark blue or black pen in the spaces provided on the Question Paper.You may use a pencil for any diagrams, graphs, or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.The number of marks is given in brackets [ ] at the end of each question or part question.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.You may use a calculator.





4

3

2

1

5

TOTAL



1 Silver bromide, AgBr, is widely used in photography. In a photographic film, AgBr crystalsare precipitated into a gelatine base as ‘grains’ of diameter about 1 × 10–6 m.

(a) Calculate the approximate number of silver ions contained in a grain of AgBr of mass2.5 × 10–12 g.

..........................................................................................................................................

.................................................................................................................................... [2]

(b) AgBr is only sparingly soluble in water. The [Ag+] in a saturated solution of AgBr canbe estimated by measuring the Ecell of the following cell.

(i) In the spaces below, identify what the four letters A – D in the above diagramrepresent.

A .................................................... C ....................................................

B .................................................... D ....................................................

(ii) Predict how the potential of the right hand electrode might vary as [Ag+] isdecreased.

..................................................................................................................................

In its saturated solution, [AgBr(aq)] = 7.1 × 10–7 mol dm–3.

(iii) Write an expression for the solubility product of AgBr, and calculate its value,including units.

..................................................................................................................................

..................................................................................................................................[7]

salt bridge

H2(g), 1 atm, 298 K

[Ag+(aq)] = x mol dm–3

A

B

C

D

2

9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use



(c) (i) Write a chemical equation representing the lattice energy of AgBr.

..................................................................................................................................

(ii) Use the following data to calculate a value for the lattice energy of AgBr(s).

first ionisation energy of silver = +731 kJ mol–1

electron affinity of bromine = –325 kJ mol–1

enthalpy change of atomisation of silver = +285 kJ mol–1

enthalpy change of atomisation of bromine = +112 kJ mol–1

enthalpy change of formation of AgBr(s) = –100 kJ mol–1

..................................................................................................................................

(iii) How might the lattice energy of AgCl compare to that of AgBr? Explain youranswer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

In photography a bromide ion absorbs a photon and releases an electron which reduces asilver ion to a silver atom.

Br– → Br + e–

Ag+ + e– → Ag

(d) Predict whether it would require more energy or less energy to initiate this process ina AgCl emulsion, compared to a AgBr emulsion. Explain your answer.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [1]

[Total: 14]

3

[Turn over9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use



2 (a) What do you understand by the term standard electrode potential?

..........................................................................................................................................

.................................................................................................................................... [2]

(b) By reference to relevant E data in the Data Booklet, explain how the halogen/halideelectrode potentials relate to the relative reactivity of the halogens as oxidising agents.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(c) Use data from the Data Booklet to construct redox equations, and calculate thestandard cell potentials, for the reactions between

(i) Acidified H2O2(aq) and KI(aq),

..................................................................................................................................

(ii) Cl2(aq) + SO2(aq).

..................................................................................................................................[4]

(d) Use data from the Data Booklet to predict the likely product of the reaction betweenI2(aq) and tin metal, writing a balanced equation for the reaction.

.................................................................................................................................... [2]

[Total: 10]

4

9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use



BLANK PAGE

5




3 (a) (i) Use the following sets of axes to sketch graphs of the variations in the meltingpoints and the electrical conductivities of the Group IV elements.

(ii) Explain how the variation in conductivity is related to the structure and bonding inthe elements.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[6]

(b) Going down Group IV there is a variation in the relative stabilities of the higher andlower oxidation states of the elements in their oxides.

Illustrating your answers with balanced chemical equations, in each of the followingcases suggest one piece of chemical evidence to show that

(i) CO is less stable than CO2,

..................................................................................................................................

..................................................................................................................................

(ii) PbO is more stable than PbO2.

..................................................................................................................................

..................................................................................................................................[3]

C

low

medium

high

melting point electric conductivity

Si Ge Sn Pb C

low

medium

high

Si Ge Sn Pb

6

9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use



(c) Name one ceramic based on silicon(IV) oxide, and explain what properties of theoxide make it suitable for this use.

..........................................................................................................................................

.................................................................................................................................... [1]

(d) Tin(II) oxide reacts with both acids and alkalis.

(i) What name is given to this property of an oxide?

..................................................................................................................................

(ii) Write suitable equations to show these two reactions of tin(II) oxide.

..................................................................................................................................

..................................................................................................................................[3]

[Total: 13]

7


ForExaminer’s

Use



4 Rodinol is used as a photographic developer. In alkaline solution it is a mild reducing agent,providing electrons according to the following half equation.

Rodinol ‘develops’ a latent photographic image by reducing activated silver bromide grainsto silver metal and bromide ions.

(a) Construct a balanced equation for the reaction between rodinol and AgBr.

.................................................................................................................................... [1]

(b) Suggest, with a reason, how the basicity of rodinol might compare to that of ammonia.

..........................................................................................................................................

..........................................................................................................................................

.................................................................................................................................... [2]

(c) Suggest structural formulae for the compounds E, F and G in the following chart of thereactions of rodinol.

[3]

NH2

rodinol

OH

E

F

G

HCl

NaOH

Br2(aq)

NH2

rodinol

OH O

O

2 OH–+ + + +H2O NH3 2e–

8

9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use

E = +0.65 V



(d) Rodinol can be synthesised from phenol by the following route.

(i) Suggest reagents and conditions for step I.

..................................................................................................................................

(ii) What type of reaction is step II?

..................................................................................................................................

(iii) Place a tick in the box by the most suitable reagent for step II.(place a tick in one box only)

H3O+ + heat

OH–(aq) + heat

Cr2O72– + H+ + heat

HNO3(aq)

Sn + HCl (aq)

NH3 in ethanol + heat/pressure

(e) Rodinol is also an important intermediate in the commercial production of theanalgesic drug paracetamol.

(i) Name two functional groups in paracetamol.

..................................................................................................................................

..................................................................................................................................

(ii) Suggest a reagent to convert rodinol into paracetamol.

..................................................................................................................................[3]

[Total: 12]

OH

NH2

OH

paracetamolNHCOCH3

[3]

OH

NO2

OH OH

NH2

I II

9


ForExaminer’s

Use



5 Hydrophilic polymers find important uses in the manufacture of contact lenses and wounddressings. Their chemical structures allow them to bond with water molecules, which keepsthem soft and flexible. Sections of two hydrophilic polymers are shown below.

(a) What type of polymerisation has produced

(i) polymer H? ...................................................

(ii) polymer J? ....................................................[2]

(b) What type of attractions might occur between these polymers and molecules of water?

.................................................................................................................................... [1]

(c) Chains of polymer H can be ‘cross-linked’, i.e. joined together, by reaction with a smallbifunctional molecule.

(i) Which one of the following molecules would be most suitable for such cross-linking?

(place a tick in one box only)

HOCH2CH2OH

H2NCH2CH2NH2

HOCH2CH2CO2H

HO2CCH2CH2CO2H

H2NCH2CH2CO2H

(ii) What type of bond would be formed during the cross-linking?

..................................................................................................................................[2]

OH

CHC

CC C

O

O

H2

OH

CHCH2

OH

CHCH2

H

H

J

N

H

H2 H2

NHN

OH

OH

OH

CH

CHCH

C

OH

CH

CH2

10

9701/04/O/N/05© UCLES 2005

ForExaminer’s

Use



ForExaminer’s

Use(d) (i) Suggest the reagents and conditions needed to hydrolyse polymer J into its

monomers.

..................................................................................................................................

(ii) Draw the structural formulae of the two products of this hydrolysis reaction.

..................................................................................................................................[3]

(e) The last compound in the list in (c)(i) above is 3-aminopropanoic acid. This can bemade from potassium chloroethanoate by the following 3-stage route.

(i) In the box above write the structure of the intermediate in this route.


stage II .....................................................................................................................

stage III ....................................................................................................................[3]

[Total: 11]

11

9701/04/O/N/05© UCLES 2005

ClCH2CO2– K+ H2NCH2CH2CO2

– K+

H2NCH2CH2CO2H

KCN stage II

stage III



BLANK PAGE

12

9701/04/O/N/05






SPA (SJF3730) T02141/3© UCLES 2006 [Turn over



CHEMISTRY 9701/04




Write your name, Centre number and candidate number in the spaces at the top of this page.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.

Answer all questions.You may lose marks if you do not show your working or if you do not use appropriate units.A Data Booklet is provided.

The number of marks is given in brackets [ ] at the end of each question or part question.At the end of the examination, fasten all your work securely together.



1

2

3

4

5

Total



2

9701/04/O/N/06

1 (a) Describe and explain how the boiling points of the tetrachlorides of the Group IVelements vary down the group.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

(b) The tetrachlorides are all covalent compounds. Draw a diagram showing the shape of amolecule of silicon tetrachloride, including values for bond angles.

[2]

(c) The noble gas xenon forms a tetrafluoride, XeF4. Only four of xenon’s outer shellelectrons are used in bonding to the fluorine atoms.

(i) Draw a dot-and-cross diagram showing how the outer-shell electrons are arrangedin XeF4.

(ii) Predict the shape and the bond angles in XeF4.

...................................................................................................................................

...................................................................................................................................[4]

(d) Describe and explain how the reactions of CCl4 and SiCl4 with water differ. Write anequation for any reaction that occurs.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

ForExaminer’s

Use

© UCLES 2006



3


(e) Many tonnes of lead tetrachloride used to be produced to make the anti-knock petroladditive tetraethyl-lead, Pb(C2H5)4, by the following reaction.

PbCl4 + ………… Na + ………… C2H5Cl ⎯⎯→ Pb(C2H5)4 + ………… NaCl

Balance this equation and use it to calculate the mass of sodium needed to produce1.0 kg of tetraethyl-lead.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

[Total: 15]

ForExaminer’s

Use

© UCLES 2006



4

9701/04/O/N/06

2 Ibuprofen is one of the most commonly used non-steroidal anti-inflammatory drugs, used totreat chronic arthritic pain caused by inflammation of the joints.

ibuprofen

(a) (i) Draw a circle around any chiral centre(s) in the above structure.

(ii) Write down the molecular formula of ibuprofen.

...................................................................................................................................

(iii) Calculate the Mr of ibuprofen and use it to calculate how many grams are needed to make 100 cm3 of a 0.15 mol dm–3 solution.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

(iv) Vigorous oxidation of ibuprofen produces a dibasic acid A. A solution containing0.10 g of A required 12.0 cm3 of 0.10 mol dm–3 NaOH for neutralisation.

Suggest a structure for A, showing your working.

...................................................................................................................................[7]

(b) The Ka value for ibuprofen is 6.3 × 10–6 mol dm–3.

(i) Write an expression for Ka.

...................................................................................................................................

(ii) Use the Ka value to calculate the pH of a 0.15 mol dm–3 solution of ibuprofen.

...................................................................................................................................

...................................................................................................................................[3]

ForExaminer’s

Use

© UCLES 2006

CH

CH2CH3

CH3C

OCH

OH

CH3



5


(c) To avoid problems with digestive irritation over a long period of use, research is beingcarried out into ways of administering ibuprofen using skin patches. For this use thecompound is dissolved in a hydrophilic gel which acts as a buffer.

(i) What do you understand by the term buffer?

...................................................................................................................................

...................................................................................................................................

The buffer used in the pharmaceutical preparation is a solution containing Na2HPO4and NaH2PO4. These salts contain the HPO4

2– and H2PO4– ions respectively.

(ii) Write equations to show how this buffer reacts with

H+ ions, ....................................................................................................................

OH– ions. .................................................................................................................

(iii) A buffer solution containing equal concentrations of the two sodium phosphatesalts has a pH of 7.20.

Calculate the pH of a pharmaceutical preparation containing 0.002 mol dm–3 ofNa2HPO4 and 0.005 mol dm–3 of NaH2PO4.

[5]

[Total: 15]

ForExaminer’s

Use

© UCLES 2006



6

9701/04/O/N/06

3 (a) (i) Write an equation showing the thermal decomposition of calcium nitrate, Ca(NO3)2.

...................................................................................................................................

(ii) State and explain how the thermal stabilities of the nitrates vary down Group II.

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................

...................................................................................................................................[4]

(b) The nitrates of calcium, strontium or barium are often added to firework mixtures toproduce red or green flames. The equation for the decomposition of one such mixture isas follows.

Sr(NO3)2(s) + 3C(s) ⎯→ SrO(s) + N2(g) + 2CO2(g) + CO(g)

Calculate the volume of gas given off (measured at room temperature and pressure)when a 10.0 g sample of this mixture decomposes. [Mr: Sr(NO3)2, 211.6]

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) Explain in detail how carbon monoxide, produced in this reaction, is poisonous.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 8]

ForExaminer’s

Use

© UCLES 2006



7


BLANK PAGE



8

9701/04/O/N/06

4 Ethylbenzene is an important starting material for making polystyrene (poly(phenylethene)).

(a) (i) State the conditions needed to carry out reaction I in the laboratory.

...................................................................................................................................

(ii) State the reagent and conditions needed for reaction II.

...................................................................................................................................

(iii) Draw the structure of the repeat unit of polystyrene.

(iv) There are several polymers that consist of phenylethene co-polymerised with othermonomers. The following formula shows part of the chain of one such co-polymer.

Deduce the structural formula of the other monomer.

[5]

CH CH2CH2 CH

CN

CH2CH

CN

CH2

ForExaminer’s

Use

© UCLES 2006

CH2CH3

+ Cl 2

reaction I

CHCl CH3

reaction II

CH CH2

polystyrene

ethylbenzene B phenylethene



9


(b) Compound B undergoes the following series of reactions.

(i) Suggest reagents and conditions for reaction III.

...................................................................................................................................

(ii) What would you see when reaction IV was carried out?

...................................................................................................................................

(iii) Draw structures for C and D in the boxes above.[4]

(c) Ethylbenzene can react with chlorine under a different set of conditions to givecompound E, an isomer of compound B. Compound E undergoes the followingreaction.

(i) Draw a structure for E in the box above.

(ii) Describe the conditions used for reaction V.

...................................................................................................................................

(iii) State the reagents used for reaction VI.

...................................................................................................................................[3]

[Total: 12]

ForExaminer’s

Use

© UCLES 2006

+

CHCl CH3

reaction III

B C D

CH(OH)CH3

reaction IV

I2 + NaOH

CH2CH3

+ Cl2

Cl

reaction V

CO2H

reaction VI

E



10

9701/04/O/N/06

ForExaminer’s

Use

© UCLES 2006

5 4-Amino-1-methylbenzene, F, is a useful starting material for making several dyes. Thefollowing chart shows some of its reactions.

(a) (i) Suggest reagents and conditions for reaction I.

...................................................................................................................................

(ii) Draw the structural formulae of compounds G and H in the boxes above.

(iii) Name the functional group you have drawn in compound G.

...................................................................................................................................[4]

CH3

CH3 NH2

Br

Br

NH2

+ CH3COCl

+ HCl

reaction II

reaction I

reaction III

H

GF



11

9701/04/O/N/06

(b) The dye J can be made from F by the following series of reactions.

Suggest reagents and conditions for

(i) reaction IV, ................................................................................................................

(ii) reaction V.

...................................................................................................................................[4]

(c) Many dyestuffs used as food colourings, such as Sunset Yellow, contain sodiumsulphonate (–SO3

–Na+) groups attached to the rings. Suggest, with an explanation, areason for this.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

[Total: 10]

N

N

SO 3 Na+

Sunset Yellow

SO 3 Na+

HO

–

–

H3C NH2

reaction IV

reaction V

H3C N2Cl

H3C

H3C

CH3

N N OH

F

J

ForExaminer’s

Use

© UCLES 2006



12

9701/04/O/N/06

BLANK PAGE






SPA (KN) T34461/2© UCLES 2007 [Turn over


*5027796699*

CHEMISTRY 9701/04

Paper 4 Structured Questions October/November 2007

1 hour 45 minutes










1

2

3

4

5

6

7

8

9

10

Total



2

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

Section A


1 (a) Use the general formula of a carboxylic acid, RCO2H, to write equations to explain the following terms.

(i) Ka .............................................................................................................................

(ii) pKa ........................................................................................................................... [2]

(b) The pKa values of four carboxylic acids are listed in the table below.

acid formula of acid pKa

1 CH3CH2CO2H 4.9

2 CH3CHCl CO2H 2.8

3 CH3CCl2CO2H 1.4

4 CH2Cl CH2CO2H 4.1

(i) Describe and explain the trend in acid strength shown by acids 1, 2 and 3.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Suggest an explanation for the difference in the pKa values for acids 2 and 4.

..................................................................................................................................

..................................................................................................................................

(iii) Calculate the pH of a 0.010 mol dm–3 solution of propanoic acid (acid 1).

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[6]



3


ForExaminer’s

Use

© UCLES 2007

(c) A good way of making synthetic amino acids uses chloro-acids as intermediates.

Cl2 + trace of P

ICH3CH2CO2H CH3CH(NH2)CO2H

alanine

NH3(excess)

IICH3CHCl CO2H

(i) Suggest the role that the trace of phosphorus plays in reaction I.

..................................................................................................................................

(ii) Write a fully balanced equation for reaction I.

..................................................................................................................................

(iii) State the type of mechanism of reaction II.

..................................................................................................................................

(iv) When 10.0 g of propanoic acid was used in this 2-stage synthesis, a yield of 9.5 g of alanine was obtained.

Calculate the overall percentage yield.

.................................................................................................................................. [5]

(d) In the solid state and in aqueous solutions, alanine exists as a zwitterion. Draw the structural formula of this zwitterion.

[2]

[Total: 15]



4

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

2 (a) Describe and explain the trend in the solubilities of the sulphates of the Group II elements.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[4]

(b) The salts formed by the Group II elements with other divalent anions show a similar trend in their solubilities, whereas most of their salts with monovalent anions are very soluble.

Use this information to predict the identities of compounds A and B in the following description of some reactions of Group II compounds, and write balanced equations for the reactions.

Magnesium hydroxide, Mg(OH)2, is almost insoluble in water. Stirring a mixture of magnesium hydroxide and aqueous ethanedioic acid, H2C2O4, produces a clear colourless solution containing A. When a solution of calcium nitrate, Ca(NO3)2, is added, a white precipitate of B is formed.

identity of A ......................................... identity of B ........................................................

equations .........................................................................................................................

......................................................................................................................................[3]

(c) The solubility product, Ksp, of magnesium hydroxide has a numerical value of 2.0 × 10–11.

(i) Write an expression for the Ksp of magnesium hydroxide, stating its units.

..................................................................................................................................

(ii) Use the value of Ksp given to calculate the concentration of Mg(OH)2 in a saturated solution.

..................................................................................................................................

..................................................................................................................................

(iii) Explain whether magnesium hydroxide would be more or less soluble in 0.1 mol dm–3 MgSO4(aq) than in water.

..................................................................................................................................

.................................................................................................................................. [5]

[Total: 12]



5


ForExaminer’s

Use

© UCLES 2007

3 The following account describes the preparation of Péligot’s salt, named after the 19th century French chemist who first made it.

Place 6.0 g of potassium dichromate(VI) in a 100 cm3 beaker and add 8.0 g of concentrated hydrochloric acid and 1.0 cm3 water. Warm the mixture gently; if carefully done the dichromate(VI) will dissolve without the evolution of chlorine. On cooling the beaker in an ice bath the solution will deposit long orange-red crystals of Péligotʼs salt.

An analysis of Péligot’s salt showed that it contained the following percentages by mass: K, 22.4%; Cr, 29.8%; Cl, 20.3%; O, 27.5%.

(a) Calculate the empirical formula of Péligot’s salt.

[2]

(b) Suggest a balanced equation for the formation of Péligot’s salt.

......................................................................................................................................[1]

(c) The instructions suggest that strong heating might cause chlorine to be evolved.

(i) What type of reaction would produce chlorine in this system?

..................................................................................................................................

(ii) Use the Data Booklet to identify relevant half equations and E o values for the production of chlorine from the reaction between K2Cr2O7 and HCl.

..................................................................................................................................

..................................................................................................................................

Use these equations to write the overall full ionic equation for this reaction.

..................................................................................................................................

(iii) The use of dilute HCl (aq) does not result in the production of chlorine. Suggest why this is so.

..................................................................................................................................

(iv) Use the Data Booklet to suggest a reason why it is not possible to prepare the bromine analogue of Péligot’s salt by using HBr(aq) instead of HCl (aq).

.................................................................................................................................. [6]

[Total: 9]



6

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

4 (a) By choosing the chlorides of two of the Group IV elements as examples, describe the trend in the reactions of these chlorides with water. Suggest an explanation for any differences, and write equations for any reactions that occur.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) The standard enthalpy changes of formation of lead(II) chloride and lead(IV) chloride are given in the following table.

compound ∆H o f / kJ mol–1

PbCl2(s) –359

PbCl4(l) –329

Use these data, and also bond energy data from the Data Booklet, to calculate the enthalpy changes for the following two reactions.

(i) CCl2(g) + Cl2(g) CCl4(g)

∆H o = ........................... kJ mol–1

(ii) PbCl2(s) + Cl2(g) PbCl4(l)

∆H o = ........................... kJ mol–1

(iii) Make use of your answers to parts (i) and (ii) to suggest how the relative stabilities of the two oxidation states vary down the Group.

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 6]



7


ForExaminer’s

Use

© UCLES 2007

5 Potassium manganate(VII) can be used to estimate the percentage of hydrogen peroxide in household bleach. The following unbalanced equation represents the reaction between them.

......... MnO–4 + ......... H2O2 + ......... H+ ......... Mn2+ + ......... H2O + ......... O2

(a) Balance this equation by putting the appropriate numbers in the spaces above. [1]

(b) Use data from the Data Booklet to calculate the E ocell for the reaction.

......................................................................................................................................[1]

(c) When 0.020 mol dm–3 KMnO4(aq) was added from a burette into an acidified 25.0 cm3 sample of H2O2, 15.0 cm3 of KMnO4 was required to reach the end-point.

(i) Describe what you would see during this titration, and also at the end-point.

..................................................................................................................................

..................................................................................................................................

(ii) Calculate the concentration of H2O2 in the sample.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [4]

[Total: 6]



8

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

6 The phenol 1-naphthol is a starting point for the manufacture of carbaryl, an insecticide and a plant growth inhibitor.

OH

1-naphthol

+ NaOH

O

carbaryl

C O

+ CH3NHCOCl

CH3NH

C

(a) (i) Suggest a structure for the intermediate C and draw it in the box above.

(ii) Name the functional groups in carbaryl.

..................................................................................................................................

..................................................................................................................................

(iii) Suggest structures for the three products formed when carbaryl is hydrolysed.

(iv) What reagents and conditions would you use for this hydrolysis?

.................................................................................................................................. [7]

(b) Suggest reagents and conditions for converting 1-naphthol into each of the following compounds.

(i)

................................................................................

OH

Br

Br

(ii)

................................................................................

[2]

OH

NO2



9


ForExaminer’s

Use

© UCLES 2007

(c) Compound D is an isomer of 4-nitro-1-naphthol. D is formed as a by-product during the reaction in b(ii). It can be converted into 2-amino-1-naphthol, E.

OH

INH2

D E

(i) Suggest the structural formula of the isomer D.

(ii) Suggest reagents needed for reaction I.

..................................................................................................................................

(iii) Suggest the structural formula of the compound formed when compound E reacts with an excess of CH3COCl.

[3]

(d) When an alkaline solution of compound E is added to a solution containing Cu2+(aq) ions, a pale green-blue precipitate F forms. Analysis of F shows that its formula is Cu(C10H8NO)2(H2O)2.

(i) Complete the following structural formula of F.

O

H2O

Cu

NH2

When an excess of concentrated NH3(aq) is added to F, the precipitate dissolves to form a deep blue solution.

(ii) State the formula of the ion responsible for the deep blue colour.

..................................................................................................................................

(iii) What type of reaction is occurring here?

..................................................................................................................................[3]

[Total: 15]



10

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

7 The nitration of benzene occurs in the following steps.

+ NO2 + H+

NO2 NO2H

++

(a) What reagents and conditions are needed for this reaction?

......................................................................................................................................[2]

(b) Write an equation showing how the electrophile NO+2 is formed from the reagents.

......................................................................................................................................[1]

(c) The nitration of methylbenzene produces mainly 2-nitromethylbenzene, whereas the nitration of benzoic acid produces mainly 3-nitrobenzoic acid.

CH3

2-nitromethylbenzene

NO2

CO2H

3-nitrobenzoic acid

NO2

Use this information to suggest suitable intermediates G and H in the following two 2-stage syntheses of chlorobenzoic acids, and suggest suitable reagents for reactions I to IV.

II

I

III

G

CO2H

Cl

CH3

IV

H

CO2H

Cl

reagents:

reaction I ................................................ reaction II ................................................

reaction III .............................................. reaction IV ............................................... [4]

[Total: 7]



11


ForExaminer’s

Use

© UCLES 2007



8 (a) DNA carries the genetic code in living organisms and consists of a double helix.

(i) Describe what is meant by a double helix.

..................................................................................................................................

..................................................................................................................................

(ii) How are the strands of the double helix held together?

..................................................................................................................................

.................................................................................................................................. [2]

(b) In replicating the genetic code two RNA molecules, mRNA and tRNA, are used to perform functions called transcription and translation.

Describe the role of the RNA molecules in these two functions.

transcription .....................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

translation ........................................................................................................................

..........................................................................................................................................

......................................................................................................................................[4]

(c) When an egg is boiled, the protein changes from a viscous liquid to a solid.

(i) Suggest what causes this change as the protein is heated.

..................................................................................................................................

..................................................................................................................................

(ii) Why is there no change to the primary structure of the protein under these conditions?

..................................................................................................................................

.................................................................................................................................. [2]



12

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

(d) Describe in outline how energy is provided in animal cells.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

[Total: 11]

9 (a) Explain with reference to energy states how 1H NMR can supply information about the structure of molecules.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[3]

(b) Nuclear magnetic resonance is used in magnetic resonance imaging scanners. These scanners are increasingly used in hospitals to detect tumours. Suggest why magnetic resonance techniques are better than X-rays.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

......................................................................................................................................[2]



13


ForExaminer’s

Use

© UCLES 2007

(c) The NMR spectrum shown below was obtained from a simple organic molecule, G, CxHyO2. When a sample of G was placed in a mass spectrometer, the ratio of the M : M+1 peaks for the molecule was 14.5 : 0.66.

11

absorbance

10 9 8 7 6 5

chemical shift, �

4 3

3

3

2

2

1 0

(i) Calculate how many carbon atoms there are in the molecule.

(ii) Use the NMR spectrum and the Data Booklet to work out the structure of G.

[5]

[Total: 10]



14

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

10 Read the following article about the use of bacteria in mining, and then answer the questions that follow it.

The discovery that bacteria could ʻmine ̓metals for us was made in Spain. The Rio Tinto mine, in the southwest corner of Spain, was originally mined for copper by the Romans some 2,000 years ago. In 1752, some mining engineers looked over the mine to see if it could possibly be re-opened. They noticed streams of a blue-green liquid running from spoil heaps of the processed rock that lay around the mine. When this blue-green liquid ran over iron, it coated the iron with a brown film. The brown film was metallic copper.

There was still some copper left in the spoil heaps. At the time, everybody thought that the copper was being dissolved in the liquid through a simple chemical reaction. But in 1947, US scientists discovered that the copper was being ʻmined ̓by a bacterium called Thiobacillus ferrooxidans.

The bacterium Thiobacillus ferrooxidans lives off the chemical energy trapped in metal sulphides. In the ore, the copper exists as copper sulphide. The bacteria gain energy by converting the copper sulphide to copper sulphate, which is then excreted. At the same time, they absorb the difference in energy in the chemical bonds. These bacteria can also obtain energy in similar reactions with ores of zinc, lead and uranium.

(a) Use the Data Booklet to explain why the blue-green liquid coated the iron with copper. Write an equation for the reaction.

..........................................................................................................................................

..........................................................................................................................................

[2]

(b) Suggest two reasons why this method of extracting copper might be useful for ore containing only a small percentage of copper.

(i) .................................................................................................................................

..................................................................................................................................

(ii) .................................................................................................................................

.................................................................................................................................. [2]

(c) Suggest one disadvantage of using bacteria rather than traditional mining and smelting methods.

..........................................................................................................................................

......................................................................................................................................[1]



15

9701/04/O/N/07

ForExaminer’s

Use

© UCLES 2007

(d) In conventional copper mining, the ore will typically contain 0.5 – 2.0% copper, which gives an idea of what a valuable resource copper is.

(i) The ore from a particular mine contains 0.75% copper, and 150 000 tonnes of ore are mined each year. From this ore about 60% of the copper is extracted, and the remainder is left in the ‘spoil heaps’ of processed ore.

What mass of copper is extracted each year?

(ii) If the use of bacteria can recover a further 17% of copper from the spoil heaps, what is the extra mass of copper produced?

[2]

(e) Suggest why bacteria are unlikely to be used in the extraction of aluminium.

..........................................................................................................................................

......................................................................................................................................[1]

(f) Metals like copper and zinc from abandoned mines can contaminate ground-water. Suggest one way of removing these contaminants.

..........................................................................................................................................

......................................................................................................................................[1]

[Total: 9]



16

9701/04/O/N/07

BLANK PAGE






SHW 00019 4/07 T63628/1© UCLES 2008 [Turn over



Write your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen.You may use a pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluidDO NOT WRITE IN ANY BARCODES.





*8268374436*

CHEMISTRY 9701/04


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

10

Total



9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

Section A


1 (a) Natural bromine consists of the two isotopes 79Br and 81Br in roughly equal proportions.

The mass spectrum of bromine consists of 5 peaks.

(i) Suggest the mass numbers for the 5 peaks and the identities of the species responsible for them.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) Suggest the ratios of the relative abundances of

• the three lines with the highest mass numbers,

..................................................................................................................................

• the two lines with the lowest mass numbers.

..................................................................................................................................[4]

Esters of 2,3-dibromopropan-1-ol with phosphoric acid are useful flame retardants used in plastics and fibres.

2,3-dibromopropan-1-ol can be made from propenal by the following two-stage process.

CH2 CH2OH

CH2

Br

CHO

CH

III

propenal

Br CH

2,3-dibromopropan-1-oIA

2



3


ForExaminer’s

Use

© UCLES 2008

(b) (i) Draw the structure of the intermediate A in the box opposite.


• reaction I,

..................................................................................................................................

• reaction II.

..................................................................................................................................[3]

(c) The mass spectrum of 2,3-dibromopropan-1-ol includes the following peaks.

mass number relative abundance

31 100

106 44

108 45

185 0.3

187 0.6

189 0.3

(i) At what mass number would you expect the molecular ion to occur?

..................................................................................................................................

(ii) Identify the molecular formula (including isotopic composition where relevant) of these 6 peaks.

mass number molecular formula

31

106

108

185

187

189

[5]

[Total: 12]



4

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

2 In the late 19th century the two pioneers of the study of reaction kinetics, Vernon Harcourt and William Esson, studied the rate of the reaction between hydrogen peroxide and iodide ions in acidic solution.

H2O2 + 2I– + 2H+ 2H2O + I2

This reaction is considered to go by the following steps.

step 1 H2O2 + I– IO– + H2O

step 2 IO– + H+ HOI

step 3 HOI + H+ + I– I2 + H2O

The general form of the rate equation is as follows.

rate = k[H2O2]a[I–]b[H+]c

(a) Suggest how the appearance of the solution might change as the reaction takes place.

.................................................................................................................................... [1]

(b) Suggest values for the orders a, b and c in the rate equation for each of the following cases.

casenumerical value

a b c

step 1 is the slowest overall



[3]

A study was carried out in which both [H2O2] and [H+] were kept constant at 0.05 mol dm–3, and [I–] was plotted against time. The following curve was obtained.

0.001

0.0009

0.0008

0.0007

0.0006

0.0005

0.0004

0.0003

0.0002

0.0001

00 30 60 90 120 150 180 210 240 270 300

time / s

[I– ion] / mol dm–3



5


ForExaminer’s

Use

© UCLES 2008

To gain full marks for the following answers you will need to draw relevant construction lines on the graph opposite to show your working. Draw them using a pencil and ruler.

(c) Calculate the initial rate of this reaction and state its units.

rate = ........................ units ....................... [2]

(d) Use half-life data calculated from the graph to show that the reaction is first order with respect to [I–].

.................................................................................................................................... [2]

(e) Use the following data to deduce the orders with respect to [H2O2] and [H+], explaining your reasoning.

[H2O2] / mol dm–3 [H+] / mol dm–3 relative rate

0.05 0.05 1.0

0.07 0.05 1.4

0.09 0.07 1.8

..........................................................................................................................................

..........................................................................................................................................

order with respect to [H2O2] = .....................................................

order with respect to [H+] = .....................................................[2]

(f) From your results, deduce which of the three steps is the slowest (rate determining) step.

.................................................................................................................................... [1]

[Total: 11]



6

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

3 (a) (i) Describe and explain the trend observed in the thermal stability of the carbonates of the Group II elements.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) By quoting suitable data from the Data Booklet suggest how the thermal stabilities of

• zinc carbonate and • lead carbonate

might compare to that of calcium carbonate.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[6]

(b) Malachite is an ore of copper. It contains the following percentages by mass.

copper 57.7% oxygen 36.2% carbon 5.4% hydrogen 0.9%

Malachite reacts with dilute H2SO4 producing a gas B that turns limewater milky and leaving a blue solution C.

When heated in the absence of air, malachite produces gas B and steam, and leaves a black solid D. D reacts with dilute H2SO4 to produce the same blue solution C.

Adding iron filings to C produces a pink solid E and a pale green solution F.

(i) Calculate the empirical formula of malachite.

..................................................................................................................................



7


ForExaminer’s

Use

© UCLES 2008

(ii) Suggest the formula of the ion responsible for the blue colour of solution C.

..................................................................................................................................

(iii) Identify the black solid D and calculate the mass of D that could be obtained by heating 10 g of malachite.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iv) Use data from the Data Booklet to identify the pink solid E and the solution F, and suggest an equation for the reaction producing them.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(v) What type of reaction is the reaction that produces E and F?

..................................................................................................................................

(vi) Describe and explain what you would see happen when dilute NH3(aq) is added slowly to the solution C until it is in an excess.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[13]

[Total: 19]



8

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

4 (a) The viscosity of engine oil can be improved by the addition of certain medium chain-length polymers.

A portion of the chain of one such polymer is shown below.

–CH2CH(CH2CH2CH3)CH2CH(CH2CH2CH3)CH2–

On average, the molecules of the medium-chain polymer contain 40 carbon atoms.

(i) Suggest the structure of the monomer.

..................................................................................................................................

(ii) How many monomer units are incorporated into the average molecule of the polymer?

..................................................................................................................................[2]

(b) Used car engine oil can be recycled for use as a fuel by the processes of distillation and cracking.

(i) Assuming a typical molecule of engine oil has the formula C40H82, suggest an equation for a cracking reaction that could produce diesel fuel with the formula C16H34 and other hydrocarbons only.

..................................................................................................................................

(ii) What conditions are needed for this cracking reaction?

..................................................................................................................................

(iii) Considering only the bonds broken and the bonds formed during the reaction, use the Data Booklet to calculate the enthalpy change for the reaction you wrote in (b)(i).

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iv) Comment on how the conditions you described in (b)(ii) relate to the enthalpy change you calculated in (b)(iii).

..................................................................................................................................

..................................................................................................................................[4]

[Total: 6]



9


ForExaminer’s

Use

© UCLES 2008

5 (4-aminophenyl)ethanoic acid (4-APEA) and its derivatives are being investigated as possible drugs to treat chronic inflammation of the intestines.

The synthesis of 4-APEA from methylbenzene is shown in the following scheme.

CH3

I II

CH2Cl

G

H3O+

HNO3 + H2SO4

NO2

NO2

V IV

III

H

CH2CN

NH2

4-APEA

CH2CO2H

(a) Draw the structures of the compounds G and H in the boxes above. [2]

(b) Suggest reagents and conditions for the following steps.

• step II

..........................................................................................................................................

• step III

..........................................................................................................................................

• step V

..........................................................................................................................................[3]

[Total: 5]



10

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

6 Suggest a test or simple reaction you could carry out on each of the following pairs of compounds to enable them to be distinguished.

(a) CH3COCH2CH2CH3 CH3CH2COCH2CH3

J K

(i) description of test or reaction

..................................................................................................................................

..................................................................................................................................

(ii) observation with compound J

..................................................................................................................................

(iii) observation with compound K

..................................................................................................................................[2]

(b)

NH2 NH2

L M


..................................................................................................................................

..................................................................................................................................

(ii) observation with compound L

..................................................................................................................................

(iii) observation with compound M

..................................................................................................................................[2]



11


ForExaminer’s

Use

© UCLES 2008

(c) CH3CH2COCl CH3CH2CH2Cl

N P


..................................................................................................................................

..................................................................................................................................

(ii) observation with compound N

..................................................................................................................................

(iii) observation with compound P

..................................................................................................................................[2]

(d) CH3CH2CONH2 CH3CH2CH2NH2

Q R


..................................................................................................................................

..................................................................................................................................

(ii) observation with compound Q

..................................................................................................................................

(iii) observation with compound R

..................................................................................................................................[2]

[Total: 8]



12

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

7 (a) Explain briefly what is meant by the word protein.

..........................................................................................................................................

.................................................................................................................................... [1]

(b) Describe how peptide bonds are formed between amino acids during the formation of a tripeptide. Include diagrams and displayed formulae in your answer.

.................................................................................................................................... [3]

(c) Describe how proteins can be broken down into amino acids in the laboratory without the aid of enzymes.

.................................................................................................................................... [2]

(d) When a small polypeptide S was broken down in this way, three different amino acids were produced according to the following reaction.

CH2

S

Mr = 165

2 NH2CHCO2H

CH3

Mr = 89

2 NH2CHCO2H +

Mr = 75

3 NH2CH2CO2H +

(i) How many peptide bonds were broken during this reaction?

..................................................................................................................................

(ii) Calculate the Mr of the polypeptide S.

Mr = .....................................................[3]

[Total: 9]



13


BLANK PAGE

13



9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008



8 (a) Enzymes play a vital role in all living organisms, helping chemical reactions to take place at body temperature.

(i) The diagram below shows the reaction pathway of an enzyme-catalysed reaction without an enzyme present. On the diagram sketch the pathway if the enzyme was present.

energy

reaction pathway

reactants

products

(ii) What type of molecule are most enzymes?

..................................................................................................................................

(iii) Why do many enzymes lose their catalytic effectiveness above 40 °C?

..................................................................................................................................[3]

(b) (i) Explain the difference between competitive and non-competitive inhibition of an enzyme.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

14



15


ForExaminer’s

Use

© UCLES 2008

(ii) The graph below shows how the rate of an enzyme-catalysed reaction varies with substrate concentration in the absence of an inhibitor.

For a given amount of enzyme, Vmax represents the rate when all of the active sites on the enzyme are being used.

reaction rate

substrate concentration

Vmax

Sketch on the diagram curves to show the effect on the rate of reaction of:

I a competitive inhibitor;

II a non-competitive inhibitor.

Clearly label your curves.[4]

(c) Heavy metal ions like Hg2+ can bind irreversibly to enzymes and this can result in poisoning.

(i) Suggest to what atom or group Hg2+ ions bind.

..................................................................................................................................

(ii) Explain how this affects enzyme activity.

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 10]



16

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

9 The technology of DNA fingerprinting has enormously advanced scientific identification techniques in medicine, crime detection and archaeology in recent years.

(a) (i) In order to prepare a DNA sample for analysis, the DNA is treated with restriction enzymes. What do restriction enzymes do?

..................................................................................................................................

..................................................................................................................................

(ii) What is the next stage in DNA analysis, after the treatment with restriction enzymes?

..................................................................................................................................

(iii) How are the DNA fragments made visible?

..................................................................................................................................[3]

(b) NMR and X-ray crystallography have made significant contributions to our knowledge of the structure of proteins and, in the pharmaceutical industry, how drugs react with target proteins.

(i) Suggest an advantage of each technique in helping to determine protein structure.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) MRI scanning is a medical technique based on NMR spectroscopy. It is particularly useful for looking for tumours in healthy tissue.

Suggest how this technique can distinguish tumour tissue from healthy tissue.

..................................................................................................................................

..................................................................................................................................[3]



17


ForExaminer’s

Use

© UCLES 2008

(c) A saturated molecule of formula CxHyNO was subjected to analysis by mass spectrometry and NMR spectroscopy. In the mass spectrum of the compound, the M peak was at m/e 73 and the ratio of the heights of the M:M+1 peak was 48 : 1.7.

(i) Using the data from the mass spectrum, determine the values of x and y in the formula of the compound.

(ii) Use the data from (i) together with the NMR spectrum below to deduce a structure for the compound, explaining how you arrive at your answer.

11 10 9 8 7 6 5

chemical shift, � / ppm

4 3 2 1 0

[4]

[Total: 10]



18

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

10 (a) Silk from silkworms, used as a fabric shows a different secondary structure to that produced by spiders.

silkworm silk spider dragline silk

less ordered� sheets

glycine rich strand

highly ordered� sheets

(i) What sort of bonding would you expect to occur between adjacent parts of the protein chains in each form of silk?

silkworm ...................................................................................................................

spider .......................................................................................................................

(ii) Suggest two differences in properties that these forms of silk could have. Explain your answer.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Spider dragline silk contains large amounts of the amino acid glycine. How does this affect the properties of the silk?

..................................................................................................................................

..................................................................................................................................[5]



19

9701/04/O/N/08

ForExaminer’s

Use

© UCLES 2008

(b) Both forms of silk are condensation polymers.

(i) Explain what is meant by a condensation polymer.

..................................................................................................................................

..................................................................................................................................

(ii) Another type of polymer is called an addition polymer. Name an example of an addition polymer.

............................................................

(iii) Suggest why condensation polymers such as proteins show a wider range of properties than addition polymers.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[5]

[Total: 10]



20

9701/04/O/N/08

BLANK PAGE






DC (FF/DT) 12823/4© UCLES 2009 [Turn over








*5

64

02

44

40

7*

CHEMISTRY 9701/41


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

Total



2

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

Section A


1 (a) The Group IV oxides CO2 and SiO2 differ widely in their physical properties. Describe these differences and explain them in terms of their structure and bonding.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

(b) What are the properties of a ceramic material? Why is silicon(IV) oxide very suitable as a component of ceramics?

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) Lead(II) oxide reacts with both acids and bases.

(i) What is the name given to oxides that have this property?

..................................................................................................................................

(ii) Write a balanced equation for the reaction between PbO and NaOH.

..................................................................................................................................[2]



3

9701/41/O/N/09© UCLES 2009 [Turn over

ForExaminer’s

Use

(d) Tin forms an oxide, A, that contains the metal in both oxidation states II and IV. The formula of A can be found by the following method.

• A sample of A was dissolved in H2SO4(aq), producing solution B, which was a mixture of tin(II) sulfate and tin(IV) sulfate.

• A 25.0 cm3 sample of solution B was titrated with 0.0200 mol dm–3 KMnO4. 13.5 cm3 of KMnO4 was required to reach the end-point.

• Another 25.0 cm3 sample of solution B was stirred with an excess of powdered zinc. This converted all the tin into tin(II). The excess of zinc powder was filtered off and the filtrate was titrated with 0.0200 mol dm-3 KMnO4, as before.

This time 20.3 cm3 of KMnO4 was required to reach the end-point.

The equation for the reaction occurring during the titration is as follows.

2MnO4– + 16H+ + 5Sn2+ 2Mn2+ + 8H2O + 5Sn4+

(i) Write a balanced equation for the reaction between Zn and Sn4+.

..................................................................................................................................

(ii) Use the Data Booklet to calculate the E o- values for the reactions between

• Zn and Sn4+, ....................................................................................................

• MnO4– and Sn2+.. ................................................................................................

(iii) Use the results of the two titrations to calculate

• the number of moles of Sn2+ in the first titration sample,

..................................................................................................................................

..................................................................................................................................

• the number of moles of Sn2+ in the second titration sample.

..................................................................................................................................

..................................................................................................................................

(iv) Use the results of your calculation in (iii) to deduce the Sn2+/ Sn4+ ratio in the oxide A, and hence suggest the formula of A.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[8]



4

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

(e) A major use of tin is to make ‘tin plate’, which is composed of thin sheets of mild steel electroplated with tin, for use in the manufacture of food and drinks cans. A tin coating of 1.0 3 10–5 m thickness is often used.

(i) Calculate the volume of tin needed to coat a sheet of steel 1.0 m 3 1.0 m to this thickness, on one side only.

..................................................................................................................................

..................................................................................................................................

(ii) Calculate the number of moles of tin that this volume represents. [The density of tin is 7.3 g cm–3.]

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) The solution used for electroplating contains Sn2+ ions. Calculate the quantity of electricity in coulombs needed to deposit the amount of tin you calculated in (ii).

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

[Total: 19]



5


BLANK PAGE



6

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

2 Calcium chloride, CaCl2, is an important industrial chemical used in refrigeration plants, for de-icing roads and for giving greater strength to concrete.

(a) Show by means of an equation what is meant by the lattice energy of calcium chloride.

..................................................................................................................................... [1]

(b) Suggest, with an explanation, how the lattice energies of the following salts might compare in magnitude with that of calcium chloride.

(i) calcium fluoride, CaF2

..................................................................................................................................

..................................................................................................................................

(ii) calcium sulfide, CaS

..................................................................................................................................

..................................................................................................................................[3]

(c) Use the following data, together with additional data from the Data Booklet, to calculate the lattice energy of CaCl2.

standard enthalpy change of formation of CaCl2 –796 kJ mol–1

standard enthalpy change of atomisation of Ca(s) +178 kJ mol–1

electron affinity per mole of chlorine atoms –349 kJ mol–1

enthalpy

Ca(s) + Cl2(g)

lattice energy = ............................................ kJ mol–1 [3]



7


ForExaminer’s

Use

(d) When a solution of CaCl2 is added to a solution of the dicarboxylic acid, malonic acid, the salt calcium malonate is precipitated as a white solid. The solid has the following composition by mass: Ca, 28.2 %; C, 25.2 %; H, 1.4 %; O, 45.2 %.

(i) Calculate the empirical formula of calcium malonate from these data.

(ii) Suggest the structural formula of malonic acid.

[3]

[Total: 10]



8

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

3 One major difference between the properties of compounds of the transition elements and those of other compounds is that the compounds of the transition elements are often coloured.

(a) Explain in detail why many transition element compounds are coloured.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [3]

(b) The following graph shows the absorption spectrum of two complexes containing copper.

absorbance

[Cu(NH3)4(H2O)2]2+

[Cu(H2O)6]2+

wavelength / nm

400 500 600 700 800 900 1000

blue green yellow red infra-red

(i) State the colours of the following complex ions.

[Cu(H2O)6]2+ .................................................................................................

[Cu(NH3)4(H2O)2]2+ .................................................................................................

(ii) Using the spectra above give two reasons why the colour of the [Cu(NH3)4(H2O)2]2+ ion is deeper (more intense) than that of the [Cu(H2O)6]2+ ion.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(iii) Predict the absorption spectrum of the complex [Cu(NH3)2(H2O)4]2+, and sketch this spectrum on the above graph. [6]



9


ForExaminer’s

Use

(c) Copper forms a complex with chlorine according to the following equilibrium.

Cu2+(aq) + 4Cl –(aq) [CuCl4]2–(aq)

(i) Write an expression for the equilibrium constant, Kc , for this reaction, stating its units.

Kc = units ...................................................... ......................................................

(ii) The numerical value of Kc is 4.2 3 105. Calculate the [[CuCl4] 2–] / [Cu2+ ] ratio when [Cl – ] = 0.20 mol dm–3.

..................................................................................................................................

..................................................................................................................................[3]

[Total: 12]



10

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

4 Cyclohexanol and phenol are both solids with low melting points that are fairly soluble in water.

OH

cyclohexanol phenol

OH

(a) Explain why these compounds are more soluble in water than their parent hydrocarbons cyclohexane and benzene.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(b) Explain why phenol is more acidic than cyclohexanol.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]



11


ForExaminer’s

Use

(c) For each of the following reagents, draw the structural formula of the product obtained for each of the two compounds. If no reaction occurs write no reaction in the box.

reagent product with cyclohexanol product with phenol

Na(s)

NaOH(aq)

Br2(aq)

I2(aq) + OH–(aq)

an excess of acidified Cr2O2

7–(aq)

[7]

(d) Choose one of the above five reagents that could be used to distinguish between cyclohexanol and phenol. Describe the observations you would make with each compound.

reagent ........................................................................................

observation with cyclohexanol ........................................................................................

observation with phenol ........................................................................................[2]

[Total: 13]



12

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

5 Kevlar is a tough polyamide used in bullet-proof vests and high-specification bicycle tyres. It can be manufactured by the following process.

I IIH3C H2N NH2CH3 HO2C

C D

Kevlar

CO2H ClOC COCl

(a) (i) Suggest reagents and conditions for

reaction I, .............................................................................................................

reaction II. .............................................................................................................

(ii) Draw the structural formula of one repeat unit of Kevlar in the box above. [4]

(b) The di-acid chloride C reacts with a variety of reagents. Suggest the structural formulae of the products of the reaction of C with

(i) CH3NH2,

(ii) HOCH2CH2OH.

[3]



13


ForExaminer’s

Use

(c) The diamine D also reacts with a variety of reagents. Suggest the structural formulae of the products of the reaction of D with

(i) HCl (aq),

(ii) Br2(aq).

[3] (d) 4-aminobenzoic acid, E, is a useful intermediate for making dyes.

III IVHO2C OH

a dye

NH2 HO2C N NCl -

HO2C N=N+

E

Suggest reagents and conditions for

reaction III, .....................................................................................................................

reaction IV. .....................................................................................................................[4]

(e) 4-aminobenzoic acid, E, forms a zwitterion.

(i) What is meant by the term zwitterion?

..................................................................................................................................

..................................................................................................................................

(ii) Draw the structural formula of the zwitterion formed from 4-aminobenzoic acid.

[2]

[Total: 16]



14

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

Section B


6 (a) The diagram shows part of one strand of DNA. Draw the complementary strand, labelling the bonds formed to the original strand, and labelling the components of the strand you draw.

phosphatesugar

T

phosphatesugar

A

phosphatesugar

C

[3]

(b) Briefly describe the roles of each of the following in protein synthesis.

(i) tRNA .........................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) the ribosome ............................................................................................................

..................................................................................................................................

.................................................................................................................................. [4]



15


ForExaminer’s

Use

(c) Some diseases, such as sickle cell anaemia, are caused by a single mutation in the DNA for a particular gene. This causes the haemoglobin produced to change the shape of red blood cells, reducing their efficiency in carrying oxygen.

(i) What is meant by a mutation?

..................................................................................................................................

(ii) Explain why such a mutation could alter the bonding in haemoglobin.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................[4]

[Total: 11]



16

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

7 This question is about the modern techniques of analysis which may be used to determine molecular structures.

(a) In X-ray crystallography X-rays are diffracted by the electron clouds surrounding individual atoms in the structure.

(i) What useful information is provided by X-ray crystallography?

..................................................................................................................................

..................................................................................................................................

(ii) Why cannot hydrogen atoms in a structure be detected by this technique?

.................................................................................................................................. [2]

(b) Suggest how structures of complex molecules such as enzymes, derived from X-ray crystallography, can help explain their biochemical behaviour.

..........................................................................................................................................

..........................................................................................................................................

..................................................................................................................................... [2]

(c) NMR spectroscopy, in contrast to X-ray crystallography, is frequently used to examine protons in organic molecules.

(i) What feature of protons enables their detection by NMR spectroscopy?

..................................................................................................................................



17


ForExaminer’s

Use

(ii) The NMR spectrum below was obtained from a compound X, CxHyOz. In the mass spectrum of the compound, the M : M+1 ratio was found to be 25:2.

Determine the values of x, y and z in the formula of X and deduce a possible structure for the compound, explaining how you arrive at your conclusion.

11 10 9 8 7 6 5 4

4

3

1

δ/ppm

3 2 1 0

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

Possible structure of X

[6] [Total:10]



18

9701/41/O/N/09© UCLES 2009

ForExaminer’s

Use

8 A new method of making very light, flexible batteries using nanotechnology was announced in August 2007. Read the passage and answer the questions related to it.

Researchers have developed a new energy-storage device that could easily be mistaken for a simple sheet of black paper. The nano-engineered battery is lightweight, ultra-thin and completely flexible. It is geared towards meeting the difficult design and energy requirements of tomorrow’s gadgets, such as implantable medical devices and even vehicles.

Researchers soaked ‘paper’ in an ionic liquid electrolyte which carries the charge. They then treated it with aligned carbon nanotubes, which give the device its black colour.

The nanotubes act as electrodes and allow the storage devices to conduct electricity. The device, engineered to function as both a battery and a supercapacitor, can provide the long, steady power output comparable to a conventional battery, as well as a supercapacitor’s quick burst of high energy. The device can be rolled, twisted, folded, or cut into shapes with no loss of strength or efficiency. The ‘paper’ batteries can also be stacked, like a pile of printer paper, to boost the total power output.

1. Conventional batteries produce electrons through a chemical reaction between electrolyte and metal.

2. Chemical reaction in the ‘paper’ battery is between electrolyte and carbon nanotubes.

3. Electrons collect on the negative terminal of a battery.

4. Electrons must flow from the negative terminal, through the external circuit to the positive terminal for the chemical reaction to continue.

nanotube



19


ForExaminer’s

Use

ForExaminer’s

Use

© UCLES 2009

(a) From your knowledge of the different structures of carbon, suggest which of these is used to make nanotubes.

..................................................................................................................................... [1]

(b) Suggest a property of this structure that makes it suitable for making nanotubes.

..........................................................................................................................................

..................................................................................................................................... [1]

(c) Carbon in its bulk form is brittle like most non-metallic solids. Suggest why the energy storage device described can be rolled into a cylinder.

..........................................................................................................................................

..................................................................................................................................... [1]

(d) Name an example of an ‘ionic liquid electrolyte’ (not a solution). ..................................................................................................................................... [1]

[Total: 4]



20

9701/41/O/N/09© UCLES 2009

9 In recent years a great deal of research has been carried out into finding different anti-cancer drugs. Tumours, which are often symptoms of cancer, are produced when cells replicate uncontrollably. This in turn is brought about by the replication of DNA in these cells.

Two anti-cancer agents are mechlorethamine and cis-platin. They work by binding to the DNA and preventing replication.

CH3

NH3

NH3

Pt

N

Cl

Cl

Cl

Cl

CH3 NG

DNA

DNA

mechlorethamine crosslinked DNA cis-platin

GNH3

NH3

Pt

G

G

C

C

(a) (i) What type of bonding attaches both anti-cancer agents to the DNA?

..................................................................................................................................

(ii) Suggest how each of the anti-cancer agents prevents replication of the DNA.

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [5]

[Total: 5]

© UCLES 2009

ForExaminer’s

Use






DC (AT/CG) 14049/2© UCLES 2009 [Turn over








CHEMISTRY 9701/42


1 hour 45 minutes




1

2

3

4

5

6

7

8

9

Total

*7729777231*



2

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

Section A


1 (a) Describe and explain qualitatively the trend in the solubilities of the sulfates of the Group II elements.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(b) The major ore of barium is barytes, BaSO4. This is very unreactive, and so other barium compounds are usually made from the sulfide, BaS. This is obtained by heating the crushed ore with carbon, and extracting the BaS with water.

BaSO4(s) + 4C(s) BaS(s) + 4CO(g)

When 250 g of ore was heated in the absence of air with an excess of carbon, it was found that the CO produced took up a volume of 140 dm3 at 450 K and 1 atm.

(i) Calculate the number of moles of CO produced.

..................................................................................................................................

(ii) Calculate the number of moles of BaSO4 in the 250 g sample of the ore.

..................................................................................................................................

(iii) Calculate the percentage by mass of BaSO4 in the ore.

.................................................................................................................................. [4]



3


ForExaminer’s

Use

(c) (i) Use the following data and data from the Data Booklet to construct a Born-Haber cycle and calculate the lattice energy of BaS.

standard enthalpy change of formation of BaS(s) –460 kJ mol–1

standard enthalpy change of atomisation of Ba(s) +180 kJ mol–1

standard enthalpy change of atomisation of S(s) +279 kJ mol–1

electron affinity of the sulfur atom –200 kJ mol–1

electron affinity of the S– ion +640 kJ mol–1

lattice energy = ............................. kJ mol–1

(ii) Explain whether the magnitude of the lattice energy of BaS is likely to be greater or less than that of BaO.

..................................................................................................................................

.................................................................................................................................. [4]

[Total: 11]



4

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

2 (a) Describe and explain how the basicities of ammonia, ethylamine and phenylamine differ.

CH3CH2NH2 NH3

NH2

ammonia ethylamine phenylamine

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(b) Describe how the use of aqueous silver nitrate and aqueous ammonia can distinguish between aqueous solutions containing chloride, bromide or iodide ions by filling in the following table.

halide observation whenAgNO3(aq) is added

observation whendilute NH3(aq) is

added

observation whenconcentrated NH3(aq)

is added

chloride

bromide

iodide

[3]

(c) Silver bromide is sparingly soluble in water.

AgBr(s) Ag+(aq) + Br–(aq) Ksp = 5 × 10–13 mol2 dm–6

(i) Calculate [Ag+(aq)] in a saturated aqueous solution of AgBr.

[Ag+(aq)] = .......................... mol dm–3

(ii) State and explain whether AgBr will be less or more soluble in 0.1 mol dm–3 KBr than it is in pure water.

..................................................................................................................................

.................................................................................................................................. [2]



5


ForExaminer’s

Use

(d) Silver ions form complexes with ammonia and with amines.

Ag+(aq) + 2RNH2(aq) [Ag(RNH2)2]+(aq)

(i) Write an expression for the Kc for this reaction, and state its units.

Kc = units ...................................................... ......................................................

Kc has the numerical value of 1.7 × 107 when R = H.

(ii) Using your expression for Kc calculate the [NH3(aq)] needed to change the [Ag+(aq)] in a 0.10 mol dm–3 solution of silver nitrate to the value that you calculated in (c)(i).

[NH3(aq)] = .......................... mol dm–3

(iii) Explain whether you would expect the Kc for the reaction where R = C2H5 to be greater or less than that for the reaction where R = H.

..................................................................................................................................

.................................................................................................................................. [5]

[Total: 13]



6

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

3 Iron metal and its compounds are useful catalysts in certain reactions.

(a) Apart from its catalytic activity, state two properties of iron or its compounds that show that it is a transition element.

..........................................................................................................................................

...................................................................................................................................... [2]

(b) You are provided with a solution of KMnO4 of known concentration in a burette. Outline how you could use this solution to find out the concentration of Fe2+(aq) in a

solution. You should include relevant equations for any reactions you describe.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [4]

(c) For each of the following equations, write the oxidation number of the element printed in bold underneath its symbol, and balance the equation by adding appropriate numbers before each species.

(i) ........ MnO–4 + ........ SO2 + ........ H2O → ........ Mn2+ + ........ SO2

4– + ........ H+

oxidation numbers: ........ ........ ........ ........

(ii) ........ Cr2O27

– + ........ NO2 + ........ H+ → ........ Cr3+ + ........ NO–3 + ........ H2O

oxidation numbers: ........ ........ ........ ........ [6]



7


ForExaminer’s

Use

(d) Outline the role that Fe3+ ions play in catalysing the reaction between iodide ions and peroxydisulfate(VI) ions.

2I– + S2O28

– I2 + 2SO24

–

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

[Total: 14]



8

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

4 (a) What is meant by the term bond energy?

..........................................................................................................................................

...................................................................................................................................... [2]

(b) Describe and explain what is observed when a red-hot wire is plunged into separate samples of the gaseous hydrogen halides HCl and HI.

How are bond energy values useful in interpreting these observations?

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [3]

(c) The following reaction occurs in the gas phase.

3F2(g) + Cl2(g) 2ClF3(g), ∆H o—r = –328 kJ mol–1

Use these and other data from the Data Booklet to calculate the average bond energy of the Cl-F bond in Cl F3. [2]

[Total: 7]



9


BLANK PAGE



10

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

5 (a) All the carbon atoms in benzene lie in the same plane. This means that they are coplanar, but this is not the case with cyclohexane.

benzene cyclohexane

By rotating the molecule around its several C–C bonds, all the carbon atoms in butane can be made to lie in the same plane, but this is not the case with methylpropane.

CH2 CH3

CH2 H3C

CH3 H3C

H3C H

butane methylpropane

By considering the 3-dimensional geometry of the following five molecules, and allowing rotations around C–C bonds, decide whether or not the carbon atoms in each molecule can be arranged in a coplanar fashion. Then place a tick in the appropriate column in the table below.

A B C

D E

CH3

CH3 CH3CH(OH)CO2H

CH3

H2N

O

O

C C

H3C

H3C

O

C

NO2

H

C

compoundall carbon atomscan be coplanar

not all carbon atomscan be coplanar

A

B

C

D

E

[3]



11


ForExaminer’s

Use

(b) Methylbenzene can react with chlorine under different conditions to give the monochloro derivatives F and G.

F G

CH3 CH3

I II

CH2Cl

Cl

Suggest reagents and conditions for each reaction.

reaction I

..........................................................................................................................................

reaction II

...................................................................................................................................... [2]



12

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

(c) Benzyl benzoate is a constituent of many perfumery products, and has also been used in the treatment of the skin condition known as scabies. It can be made from methylbenzene by the following route, which uses one of the chlorination reactions from (b).

CO2H CH2OH

CH3

III

IV

V

VI

H

C CH2

O

O

benzyl benzoate

(i) Draw the structural formula of the intermediate H in the box above.



13


ForExaminer’s

Use

(ii) Suggest reagents and conditions for each reaction.

reaction Ill

..................................................................................................................................

reaction V

..................................................................................................................................

reaction VI

..................................................................................................................................

(iii) State the type of reaction occurring during

reaction Ill,

..................................................................................................................................

reaction V. ..................................................................................................................................

[6]

[Total: 11]



14

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

6 Compounds J and K are isomers with the molecular formula C5H11NO, and they contain the same functional group.

They may both be obtained from ethanol by the following routes.

CH3CH2OH

CH3CH2CN

CH3COCl

CH3CH2COCl

(C2H7N)

NH3(excess)

V

K2Cr2O7 + H2SO4 + heatHBr + heat

L M

Q P

J K

N

I II

III IV

VI VII

(a) Draw the structural formulae of the lettered compounds J to Q in the boxes above. [7]



15


ForExaminer’s

Use

(b) Suggest reagents and conditions for the following.

reaction I

..........................................................................................................................................

reaction Il

..........................................................................................................................................

reaction IV

...................................................................................................................................... [3]

(c) What type of reaction is occurring in

reaction IV,

..........................................................................................................................................

reaction VI?

...................................................................................................................................... [2]

(d) (i) Name the functional group that is common to compounds J and K.

..................................................................................................................................

(ii) Name the functional group that is common to compounds N and P.

.............................................................................................................................. [2]

[Total: 14]



16

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

Section B


7 (a) Explain, using diagrams where appropriate, the types of interaction responsible for the primary, secondary and tertiary structure of a protein.

primary structure

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

secondary structure

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

tertiary structure

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [6]



17


ForExaminer’s

Use

(b) Enzymes are particular types of protein molecule. Explain briefly how enzymes are able to help to break down molecules in the body.

..........................................................................................................................................

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(c) The graph below shows the effect of inhibition on an enzyme-catalysed reaction.

reaction rate V

Vmax

substrate concentration [S]

State the type of inhibition shown, giving a reason to support your answer.

type of inhibition ...............................................................................................................

reason ..............................................................................................................................

...................................................................................................................................... [2]

[Total: 10]



18

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

8 The residues from organohalogen pesticides are known to be a major cause of the decline in numbers of different birds of prey in many countries. These residues are concentrated in birds at the top of food chains.

(a) Analysis of the bodies of birds of prey show that the pesticide residues accumulate in the fatty tissues of the birds. This is because of the high partition coefficient between the fat in the tissues and water found in blood.

Explain what is meant by the term partition coefficient.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(b) A particular pesticide has a partition coefficient of 8.0 between the solvent hexane and water. If a 25 cm3 sample of water containing 0.0050 g of the pesticide is shaken with a 25 cm3 sample of hexane, calculate the mass of pesticide that will dissolve in the hexane layer.

[2]

(c) Compounds used as pesticides may contain bromine or chlorine.

(i) What would be the difference in the ratio of the M: M+2 peaks if the pesticide contained one chlorine rather than one bromine atom?

..................................................................................................................................

(ii) If a given pesticide contains two chlorine atoms per molecule, deduce the relative heights of the M, M+2 and M+4 peaks.

[3]



19

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

[Turn over

(d) The following graph shows the occurrence of pesticide residues in the eggs of fish-eating birds of prey upstream and downstream of a paper mill at Castlegar on the Columbia River in Canada.

Columbia River Basin

1993

1994

1995

1996

1997

downstream of Castlegar

1993

TE

Qs

part

s pe

r tr

illio

n

1994

1995

1996

1997

20

40

60

80

100

120

upstream of Castlegar

Furan 2378TCDF

Dioxin 2378TCDD

Other Dioxins / Furans

PCBs

PCBs, the dioxin 2378TCDD, and the furan 2378TCDF all come from chemicals containing chlorine.

(i) Suggest which compounds are present directly as a result of the paper mill.

..................................................................................................................................

(ii) By studying the data for 1994, suggest which chemical(s) come from sources other than the paper mill.

..................................................................................................................................

(iii) Compare the downstream data for 1994 with that for 1997. Suggest what might be responsible for the change.

..................................................................................................................................

(iv) A molecule of 2378TCDD contains four chlorine atoms. How many molecular ion peaks would this compound show in its mass spectrum?

.................................................................................................................................. [4]

[Total:11]



20

9701/42/O/N/09© UCLES 2009

9 (a) Put the following items in order of increasing size. Use the number 1 to indicate the smallest and 3 to indicate the largest.

length of DNAmolecule in a chromosome

nanosphere diameter cell diameter

[2]

(b) Nanotechnology has an increasing range of uses across a number of fields including sport. For example, golf clubs are now being made using nanomaterials.

cross-section of normalgolf club shaft

cross-section of golf clubshaft with nanomaterial fill

Use the diagrams above and your knowledge of nanomaterials to suggest two properties of the new shafts. Explain your answers.

(i) ..................................................................................................................................

..................................................................................................................................

..................................................................................................................................

(ii) ..................................................................................................................................

..................................................................................................................................

.................................................................................................................................. [2]

ForExaminer’s

Use



21

9701/42/O/N/09© UCLES 2009

ForExaminer’s

Use

(c) A mixture of nano-sized particles of tungsten and vanadium(IV) oxide can be applied to the surface of windows and reflects heat whilst letting all light in the visible range through.

Suggest how this variable reflective property is possible using nano-sized particles.

..........................................................................................................................................

..........................................................................................................................................

...................................................................................................................................... [2]

(d) Although silver is well-known as a precious metal, its medicinal properties have been used for hundreds of years. In ancient Greece silver was used to purify water and until the development of antibiotics, silver was important in the treatment of large wounds.

(i) What property of silver makes it useful for jewellery?

..................................................................................................................................

(ii) Suggest the property of silver that makes it useful in the treatment of large wounds.

..................................................................................................................................

(iii) Suggest why nano-sized silver particles are more useful in treating wounds.

..................................................................................................................................

.................................................................................................................................. [3]

[Total: 9]



22

9701/42/O/N/09

BLANK PAGE



23

9701/42/O/N/09

BLANK PAGE



24

9701/42/O/N/09



BLANK PAGE



documentqp

Documents

mol dm3 nh3aq

ester mol dm3

mol dm3 naohaq

mol dm3 hcl

examiners use

ph changes

initial rate of run

question paper