carbon compound

[email protected] Form 5 Chapter 2

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ANALYSIS OF PAST YEAR QUESTIONS FROM 2003 - 2008

Year 2003 2004 2005 2006 2007 2008

Paper No. P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of

question S E S E S E S E S E S E S E S E S E S E S E S E

Question No 4 6 2 3 9 4 1

STRUCTURED QUESTIONS

1 SPM 2003/P2/Q4 Figure 4 shows the set-up of apparatus for the preparation of ethyl ethanoate from the

reaction of ethanol with ethanoic acid.

(a) On the Liebig condenser in Figure 4, mark ‘X’ to indicate the place where water flows

in and ‘Y’ where water flows out. [1 mark]

(b) Why is the mixture heated using a water bath?

……………………………………………………………………………………………………

……………………………………………………………………………………………………

[2 marks]

(i) Name the reaction for the preparation of ethyl ethanoate. …………………………………………………………………………………………………….

[1 mark] (ii) Write the chemical equation for the reaction in (c)(i).

…………………………………………………………………………………………………….

[1 mark] (c) The experiment is repeated by replacing ethanol with propanol

.


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(i) Name the ester formed.

…………………………………………………………………………………………………… [1 mark]

(ii) State one physical property of the ester.

…………………………………………………………………………………………………… [1 mark]

(d) The flow chart below shows the conversion of ethanol to ethane and ethanol to

ethanoic acid.

Based on the flow chart, write the chemical equation for

(e) (i) Process I. …………………………………………………………………………………………………..

[1 mark] (ii) Process II

……………………………………………………………………………………………………

[1 mark] (f) An alkene has a structural formula as shown below

What is the name of the alkane?

…………………………………………………………………………………………………….

[1 mark]

2 SPM 2004/P2/Q6 Figure 6 shows the reaction in the preparation of margarine.

(a) (i) Name the process used to produce margarine in Figure 6.

…………………………………………………………………………………………

[1 mark] (ii) State one effect of this process on the vegetable oil.

……..…………………………………………………………………………………

[1 mark ]


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(b) (i) Name catalyst X and state the range of temperature Y in the production of margarine.

Catalyst X: …………………………………………

Temperature Y: ………………………………........ oC.

[2 marks]

[Concept based on Chapter 1: Rate of reaction] (ii) Based on the collision theory, explain the effect of catalyst X and temperature Y

in the production of margarine. …………………………………………………………………………………………

…………………………………………………………………………………………

…………….……………………………………………………………………………

[3 marks] (iii) Write the chemical formula for margarine in Figure 6.

[1 mark]

(c) Name one example of a vegetable oil used in the production of margarine. ………..…………………………………………………………………………………

[1 mark] 3 SPM 2008/P2/Q4 The following information is about the compound C2H5OH.

(a) What is the name of this compound? ……………………………………………………………………………………………………

[1 mark] (b) What is the general formula for the homologous series of this compound?

…………………………………………………………………………………………………..

[1 mark]

(c) One mole of this compound undergoes complete combustion to form gas X and water as shown below.

Miscible in all proportions with water

Undergoes combustion

A member of a homologous series

C2H5OH + mO2 nX + 3H2O


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(i) State the name of gas X

…………………………………………………………………………………………

[1 mark] (ii) What are the values of m and n?

m = ………………………………………….. n = …………………………………………….

[2marks]

(d) Compound C2H5OH reacts with ethanoic acid to produce compound Y which has a sweet pleasant smell.

(i) State the name of compound Y. ……………………………………………………………………………………………

[1 mark] (ii) Draw the structural formula of compound Y.

[1 mark] (e) Compound C2H5OH undergoes dehydration to produce ethene. (i) Suggest one dehydration agent for this reaction.

…………………………………………………………………………………………...

[1 mark] (ii) Draw an apparatus set-up for this dehydration reaction to collect ethane.

[2 marks]


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4 SPM 2008/P3/Q1 Diagram 1 shows three sets, Set I, Set II and Set III, of the apparatus set-up for an

experiment to investigate the effect of ethanoic acid and ammonia solution on the coagulation of latex.

(a) State one hypothesis based on Set I and Set II. ………………………………………………………………………………………………… …………………………………………………………………………………………………..

[3 marks]

(b) Record the time taken for the latex to coagulate in Set I and Set III. Set I : ………………………………………………………………………………………….. Set III: …………………………………………………………………………………………..

[3 marks]


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(c) Construct a table to record the time taken for coagulation in Set I and Set III.

[3 marks] (d) State one observation that can be obtained from each set of this experiment.

Set I: …………………………………………………………………………………………. Set II: …………………………………………………………………………………………. Set III: ………………………………………………………………………………………….

[3 marks] (e) State the operational definition for the coagulation of latex.

………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ……………………………………………………………………………………………………

[3 marks] (f) For this experiment, state: (i) The manipulated variable

…………………………………………………………………………………………

(ii) The responding variable …………………………………………………………………………………………

(iii) The constant variable ………………………………………………………………………………………….

[3 marks] (g) (i) Excess hydrochloric acid is added to the beaker in Set II after 2:00 p.m. What

observation can be made about the latex? …………………………………………………………………………………………… ……………………………………………………………………………………………. …………………………………………………………………………………………….

[3 marks] (ii) Explain the answer in 1(g)(i)

……………………………………………………………………………………………..


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…………………………………………………………………………………………….. …………………………………………………………………………………………….

[3 marks]

(h) Explain why latex can coagulate without acid in Set III. …………………………………………………………………………………………………. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….

[3 marks] (i) (i) [Concept: F5 Chapter 1: Rate of reaction]

Explain why the latex in Set I coagulates faster than the latex in Set III. ………………………………………………………………………………………….. …………………………………………………………………………………………… …………………………………………………………………………………………..

[3 marks] (ii) The following is a list of chemical substances:

Nitric acid

Sodium hydroxide

Methanoic acid

Potassium hydroxide Classify these substances into substances that can coagulate latex and substances that cannot coagulate latex.

[3 marks]


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FORM 5 CHAPTERR 2 CARBON COMPOUNDS

Question 1 2003/P2/Q4 (a)

(b) Heat supplied is uniform (or prevents the solution from evaporating too fast) (c) (i) Esterification (ii) C2H5OH + CH3COOH CH3COOC2H5 + H2O (d) (i) Propyl ethanoate (ii)

[Note: Choose any one of the following answers] 1. Fruity smell 2. Colourless liquid 3. Low boiling point (volatile) 4. Insoluble in water

(e) (i) C2H5OH C2H4 + H2O (ii) C2H5OH + 2[O] CH3COOH + H2O (f) Butane Question 2 2004/P2/Q6 (a) (i) Hydrogenation (ii) Vegetable oil changes from liquid to solid (or changes vegetable oil from unsaturated

fats to saturated fats or changes double bond in vegetable oil molecule to single bond)

(b) (i) Catalyst X : Nickel (or platinum) Temperature : 100oC (or 200oC)

(ii) 1. Presence of catalyst reduces the activation energy 2. At a high temperature, particles possess high kinetic energy and 3. hence effective collision increases and rate of reaction increases

(iii)

or (c) Palm oil (or coconut oil or corn oil or other named oil example) Question 3 2008/P2/Q4 (a) Ethanol

(b) CnH2n+1OH (c) (i) Carbon dioxide (ii) m = 3 , n = 2 (d) (i) Ethyl ethanoate (ii)

(e) (i) [Choose any one of the following answers]

Porcelain chips or phosphoric acid or aluminium oxide


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(ii)

Question 4 2008/P3/Q1 (a) Acid coagulates latex while alkali does not coagulate latex.

(b) Set I: 5 minutes Set II: 6 hours or 300 minutes

(c)

(d) Set I: A white solid lump is formed. (or latex coagulated) Set II: There is no visible change observed. (or latex does not coagulate) Set III: A white solid lump is formed. (or latex coagulated)

(e) Operational definition for the coagulation of latex is latex becomes solid when acid is added or when exposed to air.

(f) (i) The manipulated variable : Ethanoic acid and ammonia solution (ii) The responding variable : Latex coagulates or does not coagulate. (or time taken

for coagulation of latex) (iii) The constant variable : Volume of latex, volume and concentration of acid and

ammonia solution. Temperature (g) (i) Latex coagulates after excess hydrochloric acid is added. (or latex becomes solid

after excess hydrochloric acid is added.) (ii) [For more detailed pictorial explanation, please refer to text book page 93]

When acid is added, the H+ ions from the acid neutralized the ammonia in the latex. The excess H+ ions then neutralized the negative charge on the protein membrane. The protein membrane then breaks during collision and rubber molecules combine and become entangled casing latex to coagulate.

(h) [For more explanation, please refer to text book page 93] This is because the bacteria from the air enter the latex. The growth and spread of bacteria produce lactic acid that causes the coagulation of latex.

(i) (i) Latex in Set I coagulates faster than the latex in Set III because the concentration of H+ ions is higher in Set I.

(ii)

Set Time taken / minute

I 5

III 300

Can coagulate latex Cannot coagulate latex

Nitric acid

Methanoic acid

Potassium hydroxide

Sodium hydroxide


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FORM 5 CHAPTER 2 CARBON COMPOUNDS

ANALYSIS OF PAST YEAR QUESTIONS FROM 2003 - 2008

Year 2003 2004 2005 2006 2007 2008

Paper No. P2 P3 P2 P3 P2 P3 P2 P3 P2 P3 P2 P3

Type of

question S E S E S E S E S E S E S E S E S E S E S E S E

Question No 4 6 2 3 9 4 1

1 2004/P2/Section B/Q2 Figure 2.1 shows changes of a carbon compound involving a series of reactions.

(a) Draw the structural formulae of two propanol isomers.

Name both isomers. [4 marks]

(b) [Concept: F4 Chapter 3 Chemical Formulae And Equations] The information below is regarding alkene Y: Based on the information of the alkene Y:

(i) Determine the molecular formula (ii) Draw the structural formula (iii) Name the alkene (iv) Write the general formula for its homologous series. [8 marks]

(c) (i) Table 2.2 shows the results of a test to differentiate between alkene Y and

propane.

Table 2.2

Carbon 85.7%

Hydrogen 14.3%

Relative molecular mass = 42

Relative atomic mass of H = 1 and C = 12

Procedure Observation

Bromine water is

added to alkene Y

Brown colour is

decolourized

Bromine water is

added to propane Brown colour remains


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Explain why there is difference in these observations

[4 marks]

(ii) Table 2.3 shows results of latex coagulation.

Table 2.3

Explain why there is a difference in these observations.

[4 marks] 2 SPM 2007/P2/Q9 (a) Diagram 9 shows how compound G is formed from an alkene.

Diagram 9 (i) Name one alkene that has less than four carbon atoms. Draw its structural

formula [2 marks]

(ii) Based on the answer in 2(a)(i), what is the name of compound F and

Compound G? [2 marks]

(iii) State three chemical properties of compound F and three chemical

properties of compound G.

Procedure Observation

Propanoic acid is added to latex Latex coagulates immediately

Latex is left under natural

conditions Latex coagulates slowly

Alkene + H2O

Phosphoric acid

300oC, 60 atm

Compound F

Porcelain chips

Heat

Compound G + H2O


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[6 marks]

(b) Alkene, alcohols and carboxylic acids are three different homologous series. Construct a table to show the general formula, the functional group and the name of a member in each of the series.

[10 marks]

3 SPM 2004/P3/Q3 The fruits in Figure 3.1 produce natural esters which have various tastes and scents.

FIGURE 3.1

Esters can be produced in the laboratory when an alcohol reacts with a carboxylic acid. Table 3.2 shows types of alcohol and carboxylic acid used to produce various esters. These esters have a similar scent to the esters in fruits. You are required to prepare two different types of ester using the same carboxylic acid with different alcohols. The two esters must be chosen from those shown in Table 3.2. Use the information in Table 3.2 to plan a laboratory experiment to prepare the esters and describe their scents. Your explanation should include all the followings:

(a) Aim of the experiment (b) Statement of hypothesis (c) List of substances and apparatus (d) Procedures of the experiment (e) Tabulation of data [17 marks]

Alcohol Carboxylic acid Ester Fruit

Ethanol

Methanol

Octanol

Pentanol

Butanoic acid

Butanoic acid

Ethanopic acid

Ethanoic acid

Ethyl butanoate

Methyl butanoate

Octyl ethanoate

Pentyl ethanoate

Pineapple

Apple

Orange

Banana

TABLE 3.2


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1. SPM 2006/P3/Q2 Diagram 2 shows the stretching phases of a vulcanized rubber and an unvulcanized

rubber strands.

Plan an experiment to compare one characteristic shown in Diagram 2 for both types of rubber. Your planning should include the following aspects:

(a) Aim of experiment (b) All the variables (c) Statement of the hypothesis (d) List of substances and apparatus (e) Procedure of the experiment (f) Tabulation of data.

[17 marks]


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FORM 5 CHAPTER 2 CARBON COMPOUNDS Question 1 2004/P2/Section B/Q2 (a)

Propan-1-ol Propan-2-ol

(b) (i)

No. of mol of carbon atom = 85.712

= 7.083

No. of mol of hydrogen atom = 14.3

1 = 14.1

No. of mol of carbon atom 7.083 1

No. of mol of hydrogen atom 14.3 2 (integer) (integer)

Empirical formula = CH2 Molecular formula of alkene Y : CnH2n Given relative molecular mass = 42 Hence 12n + 2n = 42 14n = 42 n = 3

molecular formula of alkene Y is C3H6

(ii)

(iii) Propene (iv) CnH2n (c) (i) 1. Alkene Y is an unsaturated hydrocarbon with a carbon-carbon double

bond.

2. When bromine water is added to alkene Y, brown colour is decolourised

because addition reaction (or bromination ) occurs.

3. Propane is a saturated hydrocarbon with carbon – carbon single bond.

4. No reaction occurs when bromine is added.

(ii) 1. Propanoic acid contains H+ ions 2. The H+ ions immediately neutralized the negative charge on the protein

membrane.

3. Hence when propanoic acid is added, latex coagulates immediately.

4. Bacteria from the air enter the latex.

5. The growth and spread of bacteria produce lactic acid slowly.

6. Hence when latex is left under natural conditions, it coagulates slowly.

Question 2 2007/P2/Q9 (a) (i)


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Ethene [ the other accepted answer is propene]

(ii) Compound F is ethanol Compound G is ethene

(iii) Chemical properties of compound F (ethanol) 1. Ethanol burns completely in air (oxygen) to produce carbon dioxide and

water. 2. Ethanol react with acidified potassium dichromate(VI) to produce

ethanoic acid. 3. Ethanol undergoes dehydration to form ethene. 4. Ethanol react with carboxylic acid to produce ester. [Choose any three.]

Chemical properties of compound G (ethene) 1. Ethene burns completely in air to produce carbon dioxide and water. 2. Ethene undergoes hydrogenation to produce ethane 3. Ethene reacts with water to form ethanol. 4. Ethene undergoes polymerization to form polyethane [Choose any three. For other accepted answers please refer to text book page 46]

(b)

Question 3 2004/P3/Q3 (a) Aim

To prepare two different types of ester using the same carboxylic acid with different alcohols and describe their scents.

(b) Hypothesis Different alcohol produces different ester.

(c) Substances

Methanol, ethanol, butanoic acid, concentrated sulphuric acid.

Apparatus

Measuring cylinder, test tubes, beakers, round bottom flask, Bunsen burner, dropper,

retort stand, test tube holder, condenser Liebig

(d) Procedure

1. Using a measuring cylinder, 25 cm3 of methanol and 50 cm3 of butanoic acid is separately measured and poured into a round bottom flask.

2. The mixture is then stirred. 3. Using a dropper, 10 drops of concentrated sulphuric acid is added and the

Homologous

series General formula Functional group Member

Alkene CnH2n Carbon – carbon

double bonds

(or C = C)

Ethene

Alcohol CnH2n+1OH Hydroxyl group

(or –OH )

Ethanol

Carboxylic

acid

CnH2n+1COOH Carboxyl group

(or COOH)

Ethanoic acid


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apparatus is set up for reflux. 4. The mixture is then heated under reflux. 5. Ester is collected in a conical flask, smelled and its scent recorded. 6. Step 1 to step 5 is repeated by replacing methanol with ethanol while butanoic

acid is used in both experiments.

(e) Tabulation of data

Question 4 2006/P3/Q2 (a) Aim of experiment

To compare the elasticity of vulcanized and unvulcanized rubber.

(b) All the variables Manipulated variable: Vulcanized rubber and unvulcanized rubber Responding variable: Change in length of rubber strip Fixed variable : Length (size) of rubber strip, mass of weight

(c) Statement of the hypothesis Vulcanized rubber is more elastic than vulcanized rubber.

(d) Substances Vulcanized rubber strip, unvulcanized rubber strip Apparatus Retort stand and clamps, Bulldog clips, metre rule, 50 g weight

(e) Procedure [Please refer to Practical chemistry book page 63 for complete diagram and procedure.]

(f) Tabulation of data

Initial length / cm

Length with weight /cm

Length after removal of weight / cm

Vulcanized rubber

Unvulcanized rubber

Alcohol Carboxylic acid Scent

carbon compound

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