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General Certificate of EducationJune 2003Advanced Subsidiary Examination

CHEMISTRY CHM3/WUnit 3(a) Introduction to Organic Chemistry

Wednesday 4 June 2003 Morning Session

In addition to this paper you will require:• a calculator.

Time allowed: 1 hour

Instructions• Use blue or black ink or ball-point pen.• Fill in the boxes at the top of this page.• Answer all questions in Section A and Section B in the spaces provided.

All working must be shown.• Do all rough work in this book. Cross through any work you do not

want marked.• The Periodic Table/Data Sheet is provided on pages 3 and 4. Detach this

perforated sheet at the start of the examination.

Information• The maximum mark for this paper is 60.• Mark allocations are shown in brackets.• This paper carries 25 per cent of the total marks for AS. For Advanced

Level this paper carries 12 12 per cent of the total marks.

• You are expected to use a calculator where appropriate.• The following data may be required.

Gas constant R = 8.31 J K–1 mol–1

• Your answers to questions in Section B should be written in continuousprose, where appropriate. You will be assessed on your ability to use anappropriate form and style of writing, to organise relevant informationclearly and coherently, and to use specialist vocabulary, whereappropriate.

Advice• You are advised to spend about 45 minutes on Section A and about

15 minutes on Section B.

For Examiner’s Use

Number

1

2

3

4

5

Mark Number Mark

Examiner’s Initials

TOTAL

Total(Column 2)

Total(Column 1)

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CHM3/W p. 1-16 3/2/03 8:56 am Page 1

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2LEAVE

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SECTION A

Answer all questions in the spaces provided.

1 (a) Butane, C4H10 , is a hydrocarbon which is used as a fuel.

(i) Explain what is meant by the term hydrocarbon.

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

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

(ii) Explain what is meant by the term fuel.

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

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

(iii) Write an equation for the complete combustion of butane.

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

(iv) Write an equation for the incomplete combustion of butane to produce carbonmonoxide and water.

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

(v) Under what conditions would you expect incomplete combustion to occur?

.............................................................................................................................................(5 marks)

(b) Three different carbocations are formed by breaking C – C bonds in separate moleculesof butane during catalytic cracking. One of these structures is shown below. Give thestructures of the other two carbocations.

Structure 1 Structure 2 Structure 3

+CH3CH2CH2

(2 marks)

CHM3/W p. 1-16 3/2/03 8:56 am Page 2

1.0

HH

ydro

gen

1

4.0H

eH

eliu

m2

10.8B

Bor

on5

12.0C

Car

bon

6

14.0N

Nitr

ogen

7

16.0O

Oxy

gen

8

19.0

FF

luor

ine

9

20.2 N

eN

eon

10

27.0 A

lA

lum

iniu

m13

28.1 S

iS

ilico

n14

31.0

PP

hosp

horu

s15

32.1

SS

ulph

ur16

35.5 C

lC

hlor

ine

17

39.9 A

rA

rgon

18

6.9

Li

Lith

ium

3

6.9

Li

Lith

ium

3

9.0B

eB

eryl

lium

4

III

IIIIV

VV

IV

II0

*58

– 7

1La

ntha

nide

s

†90

– 1

03A

ctin

ides

Key

rela

tive

atom

ic m

ass

atom

ic n

umbe

r

Th

e P

erio

dic

Tab

le o

f th

e E

lem

ents

�T

he a

tom

ic n

umbe

rs a

nd a

ppro

xim

ate

rela

tive

ato

mic

mas

ses

show

n in

the

tab

le a

re f

or u

se in

the

exa

min

atio

n un

less

sta

ted

othe

rwis

e in

an

indi

vidu

al q

uest

ion.

23.0 N

aS

odiu

m11 39

.1K

Pot

assi

um19

40.1 C

aC

alci

um20

45.0 S

cS

cand

ium

21

47.9 T

iT

itani

um22

50.9

VV

anad

ium

23

52.0 C

rC

hrom

ium

24

54.9 M

nM

anga

nese

25

55.8 F

eIr

on26

58.9 C

oC

obal

t27

58.7 N

iN

icke

l28

63.5 C

uC

oppe

r29

65.4 Z

nZ

inc

30

69.7 G

aG

alliu

m31

72.6 G

eG

erm

aniu

m32

74.9 A

sA

rsen

ic33

79.0 S

eS

elen

ium

34

79.9 B

rB

rom

ine

35

83.8 K

rK

rypt

on36

85.5 R

bR

ubid

ium

37

87.6 S

rS

tron

tium

38

88.9

YY

ttriu

m39

91.2 Z

rZ

ircon

ium

40

92.9 N

bN

iobi

um41

95.9 M

oM

olyb

denu

m42

98.9 T

cTe

chne

tium

43

101.

1 Ru

Rut

heni

um44

102.

9 Rh

Rho

dium

45

106.

4 Pd

Pal

ladi

um46

107.

9 Ag

Silv

er47

112.

4 Cd

Cad

miu

m48

114.

8 InIn

dium

49

118.

7 Sn

Tin

50

121.

8 Sb

Ant

imon

y51

127.

6 TeTe

lluriu

m52

126.

9 IIo

dine

53

131.

3 Xe

Xen

on54

132.

9 Cs

Cae

sium

55

137.

3 Ba

Bar

ium

56

138.

9 La

Lant

hanu

m57

*

178.

5 Hf

Haf

nium

72

180.

9 TaTa

ntal

um73

183.

9 WTu

ngst

en74

186.

2 Re

Rhe

nium

75

190.

2 Os

Osm

ium

76

192.

2 IrIr

idiu

m77

195.

1 Pt

Pla

tinum

78

197.

0 Au

Gol

d79

200.

6 Hg

Mer

cury

80

204.

4 Tl

Tha

llium

81

207.

2 Pb

Lead

82

209.

0 Bi

Bis

mut

h83

210.

0 Po

Pol

oniu

m84

210.

0 At

Ast

atin

e85

222.

0 Rn

Rad

on86

223.

0 Fr

Fran

cium

87

226.

0 Ra

Rad

ium

88

227 A

cA

ctin

ium

89

†

140.

1 Ce

Cer

ium

58

140.

9 Pr

Pras

eody

miu

m59

144.

2 Nd

Neo

dym

ium

60

144.

9 Pm

Pro

met

hium

61

150.

4 Sm

Sam

ariu

m62

152.

0 Eu

Eur

opiu

m63

157.

3 Gd

Gad

olin

ium

64

158.

9 Tb

Terb

ium

65

162.

5 Dy

Dys

pros

ium

66

164.

9 Ho

Hol

miu

m67

167.

3 Er

Erb

ium

68

168.

9 Tm

Thu

lium

69

173.

0 Yb

Ytte

rbiu

m70

175.

0 Lu

Lute

tium

71

232.

0 Th

Tho

rium

90

231.

0 Pa

Pro

tact

iniu

m91

238.

0 UU

rani

um92

237.

0 Np

Nep

tuni

um93

239.

1 Pu

Plu

toni

um94

243.

1 Am

Am

eric

ium

95

247.

1 Cm

Cur

ium

96

247.

1 Bk

Ber

keliu

m97

252.

1 Cf

Cal

iforn

ium

98

(252

) Es

Ein

stei

nium

99

(257

) Fm

Fer

miu

m10

0

(258

) Md

Men

dele

vium

101

(259

) No

Nob

eliu

m10

2

(260

) Lr

Law

renc

ium

103

24.3 M

gM

agne

sium

12

3

APW/0203/CHM3/W

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4

Table 1Proton n.m.r chemical shift data

Type of proton δ/ppm

RCH3 0.7–1.2

R2CH2 1.2–1.4

R3CH 1.4–1.6

RCOCH3 2.1–2.6

ROCH3 3.1–3.9

RCOOCH3 3.7–4.1

ROH 0.5–5.0

Table 2Infra-red absorption data

Bond Wavenumber/cm–1

C—H 2850–3300

C—C 750–1100

C C 1620–1680

C O 1680–1750

C—O 1000–1300

O—H (alcohols) 3230–3550

O—H (acids) 2500–3000

CHM3/W p. 1-16 3/2/03 8:56 am Page 4

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(c) Ethane can be cracked in the presence of a catalyst to produce ethene and hydrogen.

(i) Write an equation for this reaction.

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

(ii) Give a suitable catalyst for this reaction.

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

(iii) State one reason why cracking is important.

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

.............................................................................................................................................(3 marks)

TURN OVER FOR THE NEXT QUESTION

Turn over �

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2 When chlorine reacts with trichloromethane, tetrachloromethane, CCl4 , is formed.

(a) (i) Write the overall equation for this reaction.

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

(ii) State one essential condition for this reaction.

.............................................................................................................................................(2 marks)

(b) The mechanism for the chlorination of trichloromethane is free-radical substitution,which proceeds by a series of steps. Write equations for the steps named below in thischlorination.

Initiation step

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

First propagation step

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

Second propagation step

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

A termination step

.......................................................................................................................................................(4 marks)

(c) (i) A chloroalkane, W, was shown to contain 37.2% carbon and 55.0% chlorine bymass. The remainder of the compound was hydrogen. Calculate the empiricalformula of compound W.

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

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

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

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

(ii) What additional information would be needed to calculate the molecular formulaof compound W?

.............................................................................................................................................(4 marks)

Turn over �

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8LEAVE

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3 (a) Compounds with double bonds between carbon atoms can exhibit geometricalisomerism.

(i) Draw structures for the two geometrical isomers of 1,2-dichloroethene.

Isomer 1 Isomer 2

(ii) What feature of the double bond prevents isomer 1 from changing into isomer 2?

.............................................................................................................................................(3 marks)

(b) When 2-chloropropane reacts with sodium hydroxide, two different reactions occur.Each reaction produces a different organic product.

(i) Outline a mechanism for Reaction 1 and state the role of the hydroxide ion in thisreaction.

Mechanism

Role of the hydroxide ion ................................................................................................

Reaction 1 CH3—CH—CH3 + NaOH → CH3—CH—CH3 + NaCl

Cl OH

Reaction 2 CH3—CH—CH3 + NaOH → CH3—CH=CH2 + NaCl + H2O

Cl

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(ii) Outline a mechanism for Reaction 2 and state the role of the hydroxide ion in thisreaction.

Mechanism

Role of the hydroxide ion ................................................................................................(7 marks)

TURN OVER FOR THE NEXT QUESTION

Turn over �

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CHM3/W p. 1-16 3/2/03 8:56 am Page 9

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10LEAVE

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4 (a) Four isomers with the formula C4H9OH are given below.

(i) Complete the naming of the isomers in the table above.

(ii) Name the type of isomerism shown by these four isomers.

.............................................................................................................................................(3 marks)

(b) One of the isomers in part (a) is resistant to oxidation by acidified potassium dichromate(VI).

(i) Identify this isomer.

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

(ii) This isomer can be dehydrated. Give a suitable dehydrating agent and write anequation for this dehydration reaction.

Dehydrating agent ............................................................................................................

Equation ............................................................................................................................(3 marks)

NameIsomer

CH3CH2CH2CH2OH butan-1-ol

2-methylpropan-2-ol

CH3|

CH3—C—CH3|

OH

CH3—CH—CH2OH|

CH3

CH3CH2—CH—CH3|

OH

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11LEAVE

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(c) (i) Identify the isomer in part (a) which can be oxidised to a ketone. Give thestructure of the ketone formed.

Isomer ................................................................................................................................

Structure of the ketone

(ii) Identify one of the isomers in part (a) which can be oxidised to an aldehyde. Givethe structure of the aldehyde formed.

Isomer ................................................................................................................................

Structure of the aldehyde

(iii) Give a reagent that can be used in a test to distinguish between a ketone and analdehyde. State what you would observe in the test.

Reagent ..............................................................................................................................

Observation with ketone ..................................................................................................

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

Observation with aldehyde ..............................................................................................

.............................................................................................................................................(7 marks)

(d) Butan-1-ol can be oxidised to form a carboxylic acid. Using [O] to represent theoxidising agent, write an equation for this reaction and name the product.

Equation ......................................................................................................................................

Name of product .........................................................................................................................(2 marks)

Turn over �

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5 Ethene can be converted into a variety of useful products as illustrated below.

(a) Name and give a use for compound X. (2 marks)

(b) Give a reagent for each of Reactions 1, 2, 4 and 5. (4 marks)

(c) Outline a mechanism for Reaction 3. (4 marks)

(d) Ethanol can be manufactured from ethene as shown in Reaction 1 or by thefermentation of sugars. Outline the essential conditions and give an equation for thefermentation reaction. Compare the relative rates and the purity of the productobtained in each case by these two manufacturing processes. (5 marks)

END OF QUESTIONS

APW/0203/CHM3/W

12LEAVE

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SECTION B

Answer the question below in the space provided on pages 13 to 16 of this booklet.

Reaction 4

CH3CH2OHethanol

H2C=CH2ethene

Reaction 2Ag catalyst

Reaction 3HBr

O

H2C CH2

epoxyethaneCH3CH2Br

bromoethane

OH OH| |

H2C — CH2

compound X

Reaction 5

CH3CH2NH2ethylamine

Reaction 1acid catalyst

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