2010-al-chem 1

2A10-ALGHEM

PAPER 1

1.

2.

HONG KONG EXAMINATIONS AND ASSESSMENT AUTHORITY

HONG KONG ADVANCED LEVEL EXAMINATION 2O1O

CHEMISTRY A.LEVEL PAPER 1

Question-Answer Book

8.30 am - 11.30 arn (3 hours)

This paper rnust be answered in English

There are THREE sections in this paper, Section A,Section B and Section C.

Section A carries 60 marks,Section B carries 2A marks, andSection C carries 2A marks.

Answer ALL questions in Sections A and B, andONE question in Section C.

Some constants, characteristic infra-red absorptionwavenumber ranges, standard reduction potentialsand a Periodic Table can be found on pages 19 and20 of this Question-Answer Book.

lnstructions for Sections A and B :

After the announcement of the start of theexamination, you should first write your CandidateNumber in the space provided on page 1 of thisQuestion-Answer Book, and stick barcode labels inthe spaces indicated on pages 1, 3, 5, 7 and 9.

Write your answers in the spaces provided in thisQuestion-Answer Book. Do not write in the margins.Answers written in the margins will not be marked.

Supplementary answer sheets will be supplied onrequest. Write your Candidate Number, mark thequestion number box and stick a barcode label oneach sheet, and fasten them with string INSIDE thisbook.

No extra time will be given to candidates for stickingthe barcode labels or filling in the question numberboxes after the 'Time is up' announcement.

3.

4.

6

7.

5.

8

@6ffi4il&#t*.ffiHong Kong ExaminationsAll Rights Reserved 2A10

20IO.AL.CHEM I-I

{XWHFffiand Assessment Authority

Please stick the barcode label here.

Candidate Number

Marker'sUse Only

Examiner'sUse Only

Marker No. Examiner No.

B7

B8

B

Total

Checker's Use Only

Checker No.

A Total

B Total

A1

A2

A3

A4

A5

A6

ATotal

SECTION A

Answer ALL questions. Write your answers in the spaces provided'

l. (a) (i) Provide a piece ofevidence for the wave nature ofelectrons'

(iD For each of the following orbitals, sketch its pictorial representation and indicate the

location of the atomic nucleus in your diagram.

s orbital p orbital

(3 marks)

(b) A student made the following remark:

,The rate of an elementary gaseous reaction increases with temperature because the average

kinetic energy of the reactant molecules increases with temperature.'

Is the explanation provided by the student regarding the increase in reaction rate appropriate ?

Elaborate Your answer.

(3 marks)

Answers written in the margins will not be marked.

-o()

J4LdL.l-.

0)-o{-)oLi

Ba

bokcB

tr(l)

+-)

(){-)L..

Fu-)kc)Fa)-.

-cj()

J4*{cd)-.L.

c)-o{-)o

Fu)t-.boS{CB

F

(){-)l-.

e4

C)+-l

L<

aL<c)

a

22OIO.AL-CHEM I_2 m


-:().vt-.cB

)<-C)€{-,oFax

FaLi

ooldcS?1L.

o{-)l-.

I

c).l-)l-{Bu)$-{c.)

Bct)

EC)

J4LCd

-l-.c)-o+-)oL.

BcnI

bor<CS

L.L{

C.)

:)

()5){-)f-.

F(nl.<c)Fa


2OIO.AL-CHEM I_3

1. (c) Complete the table below by inserting relevant information of silicon and lead, both of whichare Group IV elements:

Silicon Lead

Electronicconfiguration of an

atom in ground state

Type of bonding insolid state

Electrical conductingproperty under roomtemperature and

atmospheric pressure

Chemical formula(e)of chloride(s)

(4 marks)

2. (a) Xenon is a noble gas. It reacts with fluorine forming a range of compounds including XeF2,XeF+ and XeFo ; but forms unstable compounds with chlorine.

(D Draw the three-dimensional structure of each of the following molecules:

XeF2

XeFa

(ii) Suggest why XeF3 does not exist.

(iii) Suggest why the compounds formed between xenon and chlorine are unstable.

(6 marks)

€(l)

J4L(€l-.l-r(us+.)oLr

FCA

l-a

bo$<d)rxo?a+)ii

Lra).t-)+)L{Fatrc)FaF.

'o6)

J4LcdL.l-.

c.)-o{rlotr

3aLa0L{GIcL.

c)rf-a5)

L{

?1-c).r-t+)l-{

=u)L0.)

F(n?1


2OIO-AL-CHEM I-4 4

d(l).vLcg

l-.

c,)-o+)ol-r

3cn

boL1dF

C)

|)

L{Cr)+)+-)*-.

FCAt{()B(t)

'(,q)JLCg

F

c)-o+-loF

3tt)l<bof{Cg

F

c)+-)

a.)+)+-,l-.

3CN!q)

3CN

t-r


20IO-AL.CHEM I-5


2. (b) From a saturated aqueous solution of calcium hydroxide, several 20.0 cm'aliquots of the solutionwere withdravvn. Each aliquot was titrated with 0.100 mol dm-3 hydrochloric acid using a

suitable indicator. The mean titre was 9.10 cm3.

Calculate

(i) the concentration of hydroxide ions in the saturated solution, and

(iD the solubility product of calcium hydroxide at the temperature of the experiment.

(4 marks)

Tl prg" rotrj

i

3. (a) Answer the following multiple-choice questions.

(i) Which of the following processes is endothermic ?

A. freezing of water

B. condensation of steam

C. reaction of H*(aq) with Otf(aq) to give HzO(l)

D. electrolysis of water

Answer

(iD Which of the transition metals below does its ground-state atom have an unpairedelectron in an s orbital ?

A. chromium

B. manganese

C. iron

D. cobalt

Answer :

(iiD Titanium has the ground-state electronic configuration: lsz 2s2 2p6 3s2 3p6 3dz 4s2 .

Which of the following compounds of titanium does not exist under room temperatureand atmospheric pressure ?

A. TiO2

B. TiCl3

c. K2Tio4

D. K3TiF6

Answer

(iv) r23I and tz'I are two isotopes of iodine. r23I is radioactive with a half-life of 13 hours

while r27I is not radioactive.

Which of the following statements about these two isotopes is/are conect ?

(l) r23I is chemically more reactive thant2\.(2) tt'I has a greater proton-to-neutron ratio than I27I.

(3) The number of l23I atoms in a sample drops to % of its original value after

26 hours.

A. (l) only

B. (2) only

C. (l) and (3) only

D. (2) and (3) only

Answer

(4 marks)

€q.)

Jlt.cgLrL{q)

.O*')ol-.

Bcn

bot<CBt-xl<

C)(d

*)t<

a)+j{-.)L{3at{c)FU)t-

ro(l)

J4LCg

)<H

().O+roF1:Fu)t1

bot<63)-.

c){-)x

L.()+-J+-)t{Bv)l<()3a


20IO.AL-CHEM I_6 6

!q)Jl

L<cstro

,o{r}oF

Fa-bo*-icsFC)

{-.1

a)+Jt'r3u)L<c.)

Fa

Ea)

t-.CS

F<

0)-o+=,o-Bct)

bo*rCg

L.L.q)

{-J

().l-)L{

Bct)t<q)

Fa:i


zOIO-AL-CHEM 1_7


7

3. (b) State the expected observation in each of the following experiments, and account for theobservation with the aid of chemical equation(s).

(i) adding excess HzSO+(aq) to K2CrOa(aq), and then excess FeSOa(aq) to the resultingsolution

(ii) adding NH3(aq) dropwise to CuSOo(aq) until in excess

(6 marks)

,m

4. Dimethyl fumarate can be found in most leather products since it is commonly used as a mould inhibitor.However, it was banned in Europe for all kinds of consumer goods in March 2009 because it was found tocause skin allergies. Compound A is an isomer of dimethyl fumarate. The structures and meltingpoints of these two compounds are given below:

cH?ooc H\lC:C/\

H COOCH3

dimethyl fumaratem.p. l02oc

HH\tC:C/\

cH3ooc coocH3

Am.p. -l goc

(a) (i) Name the type of isomerism involved.

(iD Explain why the melting point of A is lower than that of dimethyl fumarate.

(3 marks)

(b) Both dimethyl fumarate and A can be hydrolysed to their corresponding dicarboxylic acids, Band D.

HOOC H--- \ /C:C/\

H COOH

HH\lC:C/\

HOOC COOH

B D

(i)

m.p . 302oC m.p. 130oC

LHru _ - 8l I kJ mol -r LHr* : - 7gL kJ mol -r

Explain why the melting point of D is lower than that of B.

€C)JIt<CBl<F

c)-oIo

FCA

l-.boL{cBL.L.

o)

+)

c.){-)+Jl<

Fatr(.)

3a

Ec)JIf-.cdF

(.)

-o{-)o

3U)Lr

boLrcdF

C)(1€

(.)+.,*-{

>U)*<c)Fcnl-.


20IO-AL-CHEM 1_8


Ec)

J4t<dl-l-1

0.)

-o+Jot4

BU)

bol-iCB

l.{(){-)

l-.C)

l<

3U)f-.(,)

Ea

a.)J4t-(d

Ec)-o€oL

Fu)

bot-Cdl-l-r

C)

!)

()lJL.

3al..{0)FCA

l-

4. (b) (ii) Explainwhythe Al1rs of Bismore negativethanthatofD.

(4 marks)

(c) D can be converted to B by heating it with concenhated HCl. Propose a mechanism for theconversion.

(3 marks)


20IO-AL-CHEM 1_9 9Ti pug" rotrr

I

5. (a) Ketamine is a drug which has a wide range of effects in human including analgesics andanaesthesia. Ketamine can be synthesised from compound E by treating it with reagent F.

F.NHCH3

E

Give the systematic name of E.

ketamine

(i)

(Hint: The name for the substituen, "tp

as prefix is '2-chlorophenyl-' .)

(ii) (D Suggest what F is.

(II) Give the reaction conditions required for the above synthesis.

(iii) (r) If the mole ratio of E and F used in the synthesis is

side product(s) ? Explain the formation of the side1 :1, what is/are the organicproduct(s).

(II) Suggest ONE way to suppress the formation of the side product(s).

(6 marks)

€C)

-v${dF

0.).oo

Fct)Lr

e0L6d

F(){-.r

c)

L

Fcl)Sr(.)

>v)

Eo)

J4L.CS(a

C)-oIo-3cn

boLCC(1F

(.)

ts)(--C)]-)t{Bar<()3u)


20I0-AL-CHEM l-10 10

5. (b) Halofenozide is an insecticide commonly used for white grub control.from 2-methylpropene and methylbenzene as outlined below:

G(cHr)z c:cHz-------> (cHr)rccl H2NNH2>

(cHs):cNHNH2

2-methylpropene

It can be synthesised

CH:J----+

cHg

methylbenzene

CH:K-* L__-+>

CI

ofr-N/c(cH3)3

HKL

--*---+>(cH:):GNHNH2

room temperature

What are the reagen(s) and

synthesis ?

G:

CI

halofenozide

conditions represented by each of G, J, K and L in the above

J:

K:

L:

(4 marks)

'oC)

J4frCS

l-.L.

c)-o*-loe4-{

3(n)-a

b0t-'rcde1Lr

c.)

*.J

Lr

()+Jtr3ct)l<a)

Ba

'ci0)

JdLrcS

F

()-o|)o

BV)

bILr(€trH

C)1<'{-rF

o.r-)|)l.r

3cn*-.a)3al-.

Answers written in the rnargins will not be marked.

20I0-AL-CHEM 1-l l 11

6. Read the passage below and answer the questions that follow:

Ionic Liquids

Non-aqueous ionic liquids, or simply ionic liquids, generally have low vapour pressure and lowmelting point. They are becoming popular solvents in organic synthesis,

Ionic liquids mainly consist of ions, and at least one of them is a bulky organic ion.l-Ethyl-3-methylimidazolium tetrafluoroborate ([emim]BFa) is an example of ionic liquids.

t

---Nr.zi-- BF+-

[emim]*

Ionic liquids are also described as 'designer solvents' because their properties such as meltingpoint viscosity and hydrophobicity can be modified by changing the structure of their component ions.This enables them to meet the particular requirements of a synthesis.

(a) 1-Ethyl-3-methylimidazolium cation, [emim]*, is stabilised by dispersion of its positive charge.Draw structure(s) to show the dispersion of charge in [emim]*.

(1 mark)

(b) (D Some ionic liquids, including [emim]BFa, are liquid at room temperature. They arecalled 'room-temperature ionic liquids'. Account for the low melting point of suchionic liquids.

(ii) Explain why [emim]BFa has low vapour pressure.

-:()J4t<CC

1lL{

0).o|)o

F(n

oodF

()

c)+-)l<

V)tiC)

3v)

E(l)llt<Cg

)-.

c)-o+)oi.t

Fa

boL{csF

c)i,

o)

l<

FCNL<0)3V)


2010-AL-CHEM t-12 T2

6. (b) (iiD Replacing the ethyl group in [emim]BFa by a butyl group gives another ionic liquidlbmim]BFa. Which of these two ionic liquids would you expect to have a higherviscosity ? Explain.

(5 marks)

(c) Suggest THREE advantages of using ionic liquids over using organic solvents such as

CH3COCH3 and (C2H5)2O in organic synthesis. Explain your answer.

(3 marks)

(d) Suggest ONE reason which prevents ionic liquids from replacing organic solvents in organicsynthesis.

(1 mark)

END OF SECTION A

E;c.)Jt<cS)-.L{(.)

-o{-)ol-.

Bal.r

aol-.Gtrc)

+-l

()+rt-.Ba$-.q)

Frt)L.a

Eo)

J4L(clr

c.)-o!)oF.

3a

ool-{CS

Ll<q)

t-,

l-(c)

L{

q)La.)

Ba


2010-AL-CHEM l-13 13Ti prg" rotrr

i

Answer ALL questions. Write your answers

SECTION B

in the spaces provided.

the set-up of a titrimetric7. (a) The diagram below showsreaction:

experiment involving the following

Ba(OH)r(aq) + H2SOo(aq) --> BaSOa(s) + zHzO(t)

H2SO4(aq)

measuringdevice

-I -In* rJ1 x--r

LJ LI.;:C--3r-r

magneticstirrer

Ba(OH)r(aq)magnet

(D What physical parameter of the reaction mixture is measured by this set-up ?

(ii) H2SOa(aq) is added gradually to Ba(OH)r(aq) until in excess.

Sketch a graph to show the variation of the measured physical parameter with thevolume of H2SOa(aq) added. Explain your answer.

(3 marks)

-:C)

JL(sF

()-o:ro

Fa

uolic'd

Ht-.

a)

+-)

0)+.)trBaG)

3V)

Ei(.)

r<(c

l-{()

-o{-)od

3cn

boL{CC

l-()

C)

l-;cnli()

a


20IO-AL-CHEM r-14 T4

7. (b) State under what circumstances each of the following practices would be aaopteO ana exptainyour answel.

(i) the use of an air condenser instead of a water condenser in reflux

(ii) the use of concentrated H3PO4 instead of concentratedhydrogen halides from the corresponding sodium halides

H2SO4 in the preparation of

(c) The hardness of a water sample is due to Caz*(aq) ions.hardness in the sample.

(4 marks)

Outline a method for determining the

(3 marks)

-oo

J4r<rStr-a()

-o+-,ol-{

Bct)

bokCd

L{L.

o€cLc)+.){-)Lr

BC')t-.(.)

FCnI

ro()

J4lrc!0

F

C),o{-)o

Bal-rbot{(g

tsc.)

{-)(1

l<C)*)l-.

Ftt)r<o3a


2010-AL-CHEM t-15 15Ti p"g" rot"l

I

8. Acetanilide (N-phenylethanamide) can be synthesised from aniline (phenylamine) according to the

following reaction scheme:

HI

ryaniline

NHz HCI> r,yNH3*cl- (t)(cH3co)2o >W \) (2)cH3coo-Na* ry*-r:"

cHracetanilide

The procedures of the experiment are summarised below:

Step l: Dissolve 1.0 g of aniline in a mixture of 27 cm3 of water and 0.9 cm3 of concentrated

hydrochloric acid.Step 2: Using a dry syringe, inject 1.24 cm3 of ethanoic anhydride into the solution obtained in Step I.

Immediately after the injection, add sodium ethanoate solution (prepared by dissolving 1.06 g

of CHgCOONa(s) in 6 cm3 of distilled water) into the reaction mixture.

Step j: Collect the crude product by suction filtration.

(a) Suggest why it is necessary to convert aniline to its hydrochloride salt in Step 1.

(l mark)

(b) Explain why sodium ethanoate solution has to be added immediately after the injection ofethanoic anhydride in Step 2.

(1 mark)

(c) Would acetanilide be obtained in good yield if sodium ethanoate solution is added before

ethanoic anhydride ? Explain.

(2 marks)

q).yL(€Lrt-{(.)

-o{-)o-3a

boL.icd

EC)

{rJ

C){-)l-.

Bat<c)3at-.

toa)Jt<Cg

L<

c)-oIoL-

3aL{bo!CB?1l-.(){-)

c)+jt<B(ALc)Ec/)


20I0-AL-CHEM l-16 T6

8. (d) Draw a labelled diagram of the assembly of apparatus used in the suction ftltration in.Sr"pT

(2 marks)

(e) Pure acetanilide is a white solid. However, the crude product obtained appears yellow due tothe presence of impurities. Outline the experimental procedures for thl-purification of thecrude product by recrystallisation from an etlanol-water mixture.

(0

(3 marks)

Suggest a method to veri$r whether or not the recrystallised sample of acetanilide is pure.

(l mark)

END OF SECTION B

to().v

l-<CS

)-.

()rO{-)o

Fcn

oot-rdF)ri

()+,

0)+JL

V)Lc)Fa

'(,oJfiad

><

(l)-o+.ro

Ba

boL{cd

Lrq)

{-)

o|)lr

3CNr.<c)3U)


2010-AL-CHEM I -r7 T7T

l ) l P.ge rotal I

SECTION C

Answer ONE question. Write your answers in the AL(D) Answer Book.

Marks will be allocated approximately as follows:

chemical knowledge 50%organisation 30%presentation(includinguseoflanguage) 20o/o

Use equations, diagrams and examples where appropriate.

The examiners are looking for the ability to analyse, to evaluate and to express ideas.

9. Write an essay on the chemistry of the elements in Groups I and II of the Periodic Table covering theirbonding and solid state structures, reactivity and uses.

(20 marks)

10. What are synthetic polymers ? Discuss the usefulness of synthetic polymers in daily life and the fendof their development.

(20 marks)

BND OF PAPER

2010-AL-CHEM 1-18 18

Constants

Gas constant,R - 8,31 J K-l mol-l

Avogadro const ant, L - 6.02 x 1023 mol-l

Planckconstant, h-6.63 x 10-3aJs

Speed of light in vacuum, c - 3.00 x 108 m s-t

Ionic product of water at 298 K, Kr: 1.00 x 10-l a mo|z dm-6

Specific he at capactty of water : 4.I8 J gt K-t

Characteristic Infra-red Absorption Wavenumber Ranges(Stretching modes)

Bond Compound type Wavenumber range /cm-l

C:C

c:oC=C

C=N

o-H

C_H

o-H

N-H

Alkenes

Aldehydes, ketones, carboxylic acids and derivatives

Alkynes

Nitriles

Acids (hydro gen-bonded)

Alkanes, alkenes, arenes

Alcohols, phenols (hydrogen-bonded)

Amines

1610 to 1680

1680 to 1800

2070 to 2250

2200 to 2280

2500 to 3300

2840 to 3095

3230 to 3670

3350 to 3500

20IO-AL-CHEM I -19 I9

Li.(aq) + e-

K.(aq) * e-

Cat*(uq) + 2e-

Na*(aq) + e-

Mgt*(u q) + 2e-

Al3*(aq) + 3e-

Mn2*(a q) + 2e-

Vt*(uq) + 2e-

Cr2*(aq) + 2e-

Znz*(aq) + 2e-

Cr3*(aq) + 3 e-

Fe2*(aq) + 2e-

Cr3-(aq) + e-

V'*(uq) + e-

Pb2*(aq) + 2e-

ZH*(aq) + 2e-

Cu2*(aq) + e-

Soo2-(aq) + 4H*(aq) + 2e-

Cu2*(a q) + 2e-

.-

Li(s) -3.04K(s) -2.92Ca(s) -2.87Na(s) -2.71Mg(s) -2.38Al(s) -1.66Mn(s) -1.19V(s) -1 .18

Cr(s) -0.91Zn(s) -0.76Cr(s) -0 .7 4

Fe(s) -0.44Cr2*(aq) -0.41V'*(uq) -0.26Pb(s) -0.13Hz(g) 0.00

Cu*(aq) +0.15

SOz(g) + 2H2O({) +0.17

Cu(s) +0.34

VO2*(aq)+ZH*(aq)+e-

OzG) + zHzO(!) + 4e-

Cu*(aq) + e-

Iz(s) + 2e-

MnO+-(aq) * e-

Oz(g)+2H*(aq)+2e-Fe3*(aq) + e-

Ag*(uq) + e-

VOr*(aq)+2H*(aq)+e-Br2(l) + 2e-

MnO2(s) + 4H*(aq) +2e-

Oz(g)+4H*(aq)+ 4e-

Cr2O72-(aq) + 14H*(aq) + 6e-

Clr(g) + 2e-

PbO2(s)+4H*(uq) +2e-Au3*(aq) + 3 e-

MnOa-(aq) + 8H*(aq) + 5e-

Au*(aq) + e-

Fz(g) + 2e-

Standard Reduction Potentials at 298 K

Esr v aor v

= V'*(uq) + HzO(/) +0.34

= aOH-(aq) +0.40

= Cu(s) +0.52

= 2l-(aq) +0.54

+ MnOa2-(aq) +0.56

= H2O2(aq) +0.68

= Fe2*(aq) +0.77

= Ag(s) +0.80

= VO2*(aq) + HzO(t) +1.00

= 2Br-(aq) +l .07

= Mn2*(aq) + ZHzO(t) +1 .23

= 2HzO(!) +1.23

= ZCr3*(aq) + 7H2O(0 +1.33

+ 2Cl-(aq) +1.36

= pb2*(aq) + ZHzO(t) +1.47

+ Au(s) +1.50

= Mn2*(aq) + 4H2O(l) +1.51

+ Au(s) +1.69

= 2F-(aq) +2.87

Periodic Table

atomic number

GROUP

I II

relative atomic mass

III IV V VI VII

2He40

1JLi6.9

4Be9.0

5

B10 8

6C12.0

7N14.0

8

o16.0

9F19.0

l0Ne202

llNa23.0

t2Mg24.3

1iAI270

14Si28.r

l5P3 1.0

16

S32 1

T7

CI35.5

18Ar40.0

19K39. l

20Ca40. I

2lSc450

22Ti47 .9

23v509

24Cr520

25Mn549

26Fe558

27Co58 9

28 "29\i CU

58. 535

30Zn65.4

31Ga69.7

32Ge72.6

33 134As lSe749 "94

35Br799

36Kr838

37Rb85.5

38Sr87 .6

39Y889

40Zr9t2

4lNb92.9

42IIo959

13 111 J5 16Tc : Ru 'Rh Pdi98r lr-t1 1 1'-11 9 i06 I

111tAg107.9

48Cdll2 4

49In114.8

50Sn118

51

Sb121 8

52Ter27 .6

53I126 9

54Xe131 3

55Csr32.9

56Bar37 .3

57*Lt138.9

72Hf178.5

73Ta180 9

i1\1'183 9

\h

n, Ot Ir186l ii90l i9ll

-8Pt195.1

79Aut97 .0

80Hg200.6

81TI204 1

82Pbza7 2

8iBi209.0

84PoQ0e)

8sAt(210)

86RnQ22\

87FrQ23\

88RaQ26\

89 **AcQ27\

104Rf(26r)

105DbQ62\

58Ce140 1

59Pr140.9

60Nd144.2

61Pm( r45)

62Sm150 4

63Eu152 0

6+Gdr57 3

65Tb158.9

66Dy162.5

67Ho164.9

68Er167.3

69Tm168 9

70Ybr73 0

7lLu175.0

90Th232.0

91Pa(23 1)

92U238.0

93Np(237)

94PuQ44\

95Am(243\

96Cmt747 )

97BKQ47\

98CfQsr

99Es(252)

100Fm(257)

101Md(258)

102NoQs9\

103Lr(260 )

20I0-AL-CHEM I -20 20

2010-al-chem 1

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