TIME

1 hour 30 minutes.

INSTRUCTIONS TO CANDIDATES

Write your Centre Number and Candidate Number in the spaces

provided at the top of this page.

Answer all fifteen questions.

Answer all ten questions in Section A. Record your answers by

marking the appropriate letter on the answer sheet provided. Use only

the spaces numbered 1 to 10. Keep in sequence when answering.

Answer all five questions in Section B. Write your answers in the

spaces provided in this question paper.

INFORMATION FOR CANDIDATES

The total mark for this paper is 90.

Quality of written communication will be assessed in

question 14(a)(iv).In Section A all questions carry equal marks, i.e. two marks for each

question.

In Section B the figures in brackets printed down the right-hand side

of pages indicate the marks awarded to each question or part question.

A Periodic Table of Elements (including some data) is provided.

A2C1S8 3606

ADVANCEDGeneral Certificate of Education

2008

Chemistry

Assessment Unit A2 1

assessing

Module 4: Further Organic, Physical and

Inorganic Chemistry

[A2C11]

THURSDAY 22 MAY, MORNING

A2C

11

71

Centre Number

Candidate Number

For Examiner’s use only

Question Marks

Number

Section A

1–10

Section B

11

12

13

14

15

TotalMarks

A2C1S8 3606 2 [Turn over

Section A

For each of the questions only one of the lettered responses (A – D) is correct.

Select the correct response in each case and mark its code letter by connecting the dots as illustrated on the answer sheet.

1 The slowest stage in the production of sulphuric acid involves the conversion of sulphur

dioxide to sulphur trioxide.

2SO2(g) + O

2(g) 2SO

3(g) ΔH = –197 kJ

What effect does adding a catalyst have on the rates of the forward and reverse

reactions and the equilibrium constant?

rate of forward reaction rate of reverse reaction equilibrium constant

A decreases decreases increases

B increases increases increases

C increases decreases no effect

D increases increases no effect

2 The partition coefficient of an organic compound X between ether and water is 20.

An aqueous solution containing 5.00 g of X in 250 cm3 of water was shaken with 100 cm3 of

ether. What mass of X remained in the aqueous layer following the extraction?

A 0.56 g

B 1.67 g

C 3.33 g

D 4.44 g

3 For the reaction

H2SO

4 + HNO

3 → HSO

4– + H

2NO

3+

HNO3 is the

A conjugate acid of H2NO

3+

B conjugate acid of HSO4–

C conjugate base of H2NO

3+

D conjugate base of HSO4–

A2C1S8 3606 3 [Turn over

4 Which one of the following reactions in the Born–Haber cycle for potassium iodide is

exothermic?

A KI(s) → K+(g) + I–(g)

B K(g) → K+(g) + e–

C I2(g) → 2I(g)

D I(g) + e– → I–(g)

5 The pharmaceutical drug antifebrin, CH3CONHC

6H

5, is made by the reaction of ethanoic

anhydride with phenylamine.

(CH3CO)

2O + C

6H

5NH

2 → CH

3CONHC

6H

5 + CH

3COOH

6.0 g of ethanoic anhydride, (CH3CO)

2O, reacted with 4.0 g of phenylamine, C

6H

5NH

2, to

produce 3.8 g of antifebrin. The percentage yield is

A 48.6%

B 63.3%

C 65.4%

D 95.0%

6 In which one of the following reactions is no gas evolved?

A copper metal with concentrated nitric acid

B concentrated sulphuric acid with solid potassium iodide

C thionyl chloride with ethanoic acid

D aqueous sodium sulphite with potassium manganate(VII) solution

A2C1S8 3606 4 [Turn over

7 The mechanism for the reaction between propanone and iodine proceeds in a

series of steps as follows:

CH3COCH

3 + H

3O+ → CH

3C(OH)+CH

3 + H

2O slow

CH3C(OH)+CH

3 + H

2O → CH

2 = C(OH)CH

3 + H

3O+ fast

CH2

= C(OH)CH3 + I

2 → CH

2ICOCH

3 + HI fast

The orders with respect to propanone, hydroxonium (H3O+) and iodine which support this

would be:

CH3COCH

3 H

3O+ I

2

A 1 1 0

B 1 0 0

C 0 0 1

D 1 1 1

8 Which one of the following equimolar salt solutions would have the highest pH?

A ammonium chloride

B ammonium ethanoate

C sodium chloride

D sodium ethanoate

9 Ammonia may be oxidised by mixing it with air and passing the mixture over a heated

platinum–rhodium catalyst.

4NH3(g) + 5O

2(g) → 4NO(g) + 6H

2O(g)

Assuming air to be 20% oxygen, what volume of air is needed to react completely with

10.0 dm3 of ammonia at 20 °C and 1 atmosphere pressure?

A 12.5 dm3

B 40.0 dm3

C 50.0 dm3

D 62.5 dm3

A2C1S8 3606 5 [Turn over

10 Given the following half-equations

E / V

Br2(aq) + 2e– → 2Br–(aq) +1.07

O2(g) + 4H+(aq) + 4e– → 2H

2O(l) +1.23

S2O

82–(aq) + 2e– → 2SO

42–(aq) +2.01

which one of the following species could oxidise water to oxygen?

A Br–(aq)

B Br2(aq)

C SO4

2–(aq)

D S2O

82–(aq)

A2C1S8 3606 6 [Turn over

Examiner Only

Marks Remark

Section B

Answer all five questions in the spaces provided.

11 Glucose is a white crystalline solid which exhibits the reactions of an

aliphatic aldehyde. Its structure can be represented as:

CHO

CHOH

CHOH

CHOH

CHOH

CH2OH

(a) State what is observed when glucose is boiled with Fehling’s solution.

______________________________________________________ [1]

(b) Glucose is optically active.

(i) Explain the meaning of the term optically active.

_____________________________________________________

___________________________________________________ [1]

(ii) How many asymmetric centres are there in a glucose molecule?

___________________________________________________ [1]

A2C1S8 3606 7 [Turn over

Examiner Only

Marks Remark

(c) Draw the structure of the product formed between glucose and

2,4-dinitrophenylhydrazine, representing glucose as RCHO.

[2]

(d) Fermentation of glucose produces ethanol and carbon dioxide.

The reaction is catalysed by the enzyme zymase found in yeast.

(i) Write an equation for the fermentation of glucose.

___________________________________________________ [2]

(ii) State what effect the enzyme has on the activation energy for this

reaction.

___________________________________________________ [1]

A2C1S8 3606 8 [Turn over

12 Nitrogen monoxide, NO, is a colourless gas which is formed in the reaction

between moderately concentrated nitric acid and copper metal. In the

presence of air it is immediately oxidised to the dioxide.

(a) Write the equation for the formation of nitrogen monoxide from nitric

acid and copper.

______________________________________________________ [2]

(b) The oxidation of nitrogen monoxide is represented by the equation:

2NO(g) + O2(g) → 2NO

2(g)

The kinetics of this reaction were studied and the following results

recorded.

Experiment

Initialconcentration of

NO × 10–3 mol dm–3

Initialconcentration of

O2 × 10–3 mol dm–3

Initial rate× 10–4

mol dm–3 s–1

1 1 1 6

2 2 1 24

3 3 1 54

4 2 2 48

5 3 3 162

(i) Using these results, deduce the order of the reaction with respect to

nitrogen monoxide and oxygen and write the overall rate equation.

order with respect to NO _________________________________

order with respect to O2 __________________________________

rate equation ________________________________________ [3]

(ii) On the axes below, sketch the shape of the graph expected in each

case.

[2]

[NO]

time

rate

[NO]

Examiner Only

Marks Remark

A2C1S8 3606 9 [Turn over

(iii) Use the results for experiment 1 to determine the value of the rate

constant and state its units.

______________________________________________________

______________________________________________________

___________________________________________________ [3]

(c) Nitrogen dioxide, NO2, is a brown gas which dimerises to form

colourless dinitrogen tetroxide, N2O

4. The following equilibrium is

established.

N2O

4(g) 2NO

2(g) ΔH = + 58 kJ

(i) State and explain the effect of reducing the total pressure on the

above equilibrium.

______________________________________________________

______________________________________________________

___________________________________________________ [2]

(ii) A sealed flask containing pure dinitrogen tetroxide was heated to

80 °C and equilibrium allowed to establish. At equilibrium, the

total pressure was 125 kPa and the mole fraction of dinitrogen

tetroxide was found to be 0.20. Calculate the value of Kp for this

reaction, stating its units.

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

___________________________________________________ [4]

(iii) State and explain the effect of increasing the temperature on the

value of Kp.

______________________________________________________

______________________________________________________

___________________________________________________ [2]

Examiner Only

Marks Remark

A2C1S8 3606 10 [Turn over

Examiner Only

Marks Remark

(d) Nitrogen dioxide dissolves in water to form an acidic solution.

2NO2 + H

2O → HNO

3 + HNO

2

The nitrous acid decomposes to form more nitric acid.

(i) Explain the relative strengths of nitrous and nitric acids.

______________________________________________________

______________________________________________________

___________________________________________________ [2]

(ii) Given the half equations

VO2+(aq) + 2H+(aq) +e– V3+ + H2O(l) E = +0.34 V

NO3–(aq) + 4H+(aq) + 3e– NO(g) + 2H

2O(l) E = +0.96 V

VO2+(aq) + 2H+(aq) + e– VO2+(aq) + H

2O(l) E = +1.00 V

deduce the equation for the reaction which occurs when nitric acid

is added to a solution containing a mixture of V3+ and VO2+ ions.

___________________________________________________ [2]

(iii) A text book notes that “nitrous acid can act as both an oxidising agent and a reducing agent”. With reference to oxidation number,

explain this statement by referring to the reactions of the acid with

acidified aqueous solutions of iron(II) sulphate and potassium

manganate(VII).

______________________________________________________

______________________________________________________

______________________________________________________

___________________________________________________ [4]

A2C1S8 3606 11 [Turn over

Examiner Only

Marks Remark

13 Using only elements from the third period of the Periodic Table, answer the

following questions.

(a) (i) Write the formula of the metallic chloride which contains both

covalent and coordinate (dative) bonds.

___________________________________________________ [1]

(ii) Which element forms an oxide in which its oxidation state is +5?

___________________________________________________ [1]

(iii) Name the element which forms an oxide with a giant covalent

structure.

___________________________________________________ [1]

(b) Aluminium oxide is amphoteric.

(i) Explain the term amphoteric.

______________________________________________________

___________________________________________________ [1]

(ii) Write the equation for the reaction between aluminium oxide and

sulphuric acid.

___________________________________________________ [2]

A2C1S8 3606 12 [Turn over

Examiner Only

Marks Remark

14 Linoleic acid (octadeca-9,12-dienoic acid), is one of two essential fatty

acids in our diet since our bodies are unable to synthesise it.

CH3(CH

2)4CH = CHCH

2CH = CH(CH

2)7COOH

linoleic acid

Deficiency can lead to scaly skin and hair loss. Glyceryl esters of the acid

are plentiful in sunflower oil.

(a) (i) The configuration at each double bond is cis. Draw the structure of

linoleic acid.

[1]

(ii) Draw the structure of the oil formed when one molecule of glycerol

reacts with three molecules of linoleic acid, representing the acid

as C17

H31

COOH.

[2]

(iii) The iodine value for sunflower oil is typically in the range

125–145, while that of butter is 26–45. Explain these differences.

______________________________________________________

___________________________________________________ [2]

A2C1S8 3606 13 [Turn over

Examiner Only

Marks Remark

(iv) Describe how the iodine value of a sample of sunflower oil may be

determined.

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

___________________________________________________ [4]

Quality of written communication [2]

(b) Rancidity results from the oxidation of fats and oils in the absence of

enzymes. This autoxidation may be slowed down by the addition of

antioxidants such as citric acid which has the structure:

CH2COOH

HO C COOH

CH2COOH

(i) Write an equation to show the reaction of citric acid with excess

sodium hydroxide solution.

___________________________________________________ [2]

(ii) Titration of 25.0 cm3 of a citric acid solution required 17.5 cm3 of

0.1 M sodium hydroxide solution. Calculate the concentration of

citric acid in g dm–3.

______________________________________________________

______________________________________________________

______________________________________________________

___________________________________________________ [4]

A2C1S8 3606 14 [Turn over

Examiner Only

Marks Remark

15 Aldehydes and ketones are responsible for many familiar smells.

Benzaldehyde is used to make almond essence while heptan-2-one gives

blue cheese its odour.

CH3COCH

2CH

2CH

2CH

2CH

3

benzaldehyde heptan-2-one

C6H

5CHO

(a) Fruits such as apricots contain amygdalin, C20

H27

O11

N, which is

hydrolysed by enzymes to form benzaldehyde, glucose and

hydrogen cyanide. Write the equation for this reaction.

______________________________________________________ [2]

(b) Benzaldehyde reacts with hydrogen cyanide to form benzaldehyde

cyanohydrin.

(i) Suggest the flow scheme for the mechanism of this reaction.

[3]

(ii) Name the mechanism of this reaction.

___________________________________________________ [2]

C

H O

Examiner Only

Marks Remark

(c) Benzaldehyde may be oxidised using acidified potassium

manganate(VII) to form benzoic acid, C6H

5COOH. Benzoic acid is a

weak acid with an acid dissociation constant, Ka, of 6.3 × 10–5 mol dm–3.

Calculate the pH of a 0.001 M solution of benzoic acid.

_________________________________________________________

_________________________________________________________

_________________________________________________________

______________________________________________________ [3]

(d) (i) Explain the relative solubilities of propanone and

heptan-2-one in water.

______________________________________________________

______________________________________________________

___________________________________________________ [2]

(ii) Name the organic product formed when heptan-2-one reacts with

lithal, LiAlH4.

___________________________________________________ [1]

THIS IS THE END OF THE QUESTION PAPER

A2C1S8 3606 15 [Turn over

S – 4/07 – 529-024-1 [Turn over