*1792185691*

CHEMISTRY 0620/42

Paper 4 Theory (Extended) February/March 2020

1 hour 15 minutes

You must answer on the question paper.

No additional materials are needed.

INSTRUCTIONS ● Answer all questions. ● Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. ● Write your name, centre number and candidate number in the boxes at the top of the page. ● Write your answer to each question in the space provided. ● Do not use an erasable pen or correction fluid. ● Do not write on any bar codes. ● You may use a calculator. ● You should show all your working and use appropriate units.

INFORMATION ● The total mark for this paper is 80. ● The number of marks for each question or part question is shown in brackets [ ]. ● The Periodic Table is printed in the question paper.

IB20 03_0620_42/2RP© UCLES 2020 [Turn over

This document has 12 pages. Blank pages are indicated.

Cambridge IGCSE™

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0620/42/F/M/20© UCLES 2020

1 Petroleum is a useful natural resource.

The diagram shows how petroleum can be separated into useful substances.

kerosene fraction

A

gasoline fraction

refinery gas

diesel oil

fuel oil fraction

petroleum

lubricating oil fraction

B

(a) What is the name of the separation process shown in the diagram?

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

(b) Name the fraction leaving at:

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

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

(c) Refinerygasisamixtureofhydrocarbons.

Onerefinerygasisbutane,C4H10.

(i) Suggest the names of twootherrefinerygases.

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

(ii) Write the chemical equation for the complete combustion of butane.

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

(iii) Namethetoxicgasproducedbytheincompletecombustionofbutane.

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

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(d) Gasolineandkerosenearebothfuels.Theyhavedifferentproperties.

(i) Describe the differences in the properties given.

viscosityofthefuel .............................................................................................................

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

flammabilityofthefuel ........................................................................................................

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

(ii) What difference in the molecules of gasoline and kerosene causes these differences in properties?

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

(e) Hydrogenfuelcellscanbeusedtopowervehicles.

Writethewordequationfortheoverallreactionthattakesplaceinahydrogenfuelcell.

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

[Total: 13]

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2 Aluminiumisextractedfromitsore.Theoreisconvertedintopurealuminiumoxide,whichthenundergoeselectrolysisasshown.

+ +

+ –

anodes

powersupply

electrolyte

molten aluminium

wires

cathode

(a) (i) Name an ore of aluminium.

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

(ii) Whatismeantbythetermelectrolysis?

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

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

(b) Aluminiumoxidehasameltingpointofabout2000°C,buttheelectrolysisprocessoperatesatabout 900 °C.

(i) Namethecompoundaddedtoaluminiumoxidetoreducetheoperatingtemperature.

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

(ii) Suggest onebenefittotheenvironmentofreducingtheoperatingtemperature.

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

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

(iii) Write the ionic half-equation for the reaction taking place at:

the negative electrode (cathode) ........................................................................................

the positive electrode (anode) ............................................................................................ [4]

(iv) Explainwhytheanodesneedfrequentreplacement.

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

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

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(c) Aluminiumoxidereactswithacidsandwithalkalis.

(i) Whattermisusedtodescribeanoxidethatreactswithacidsandwithalkalis?

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

(ii) Aluminiumoxidereactswithdilutesulfuricacidtoformasalt.

State the name and write the formula of the salt formed.

name ...................................................................................................................................

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

(iii) Aluminiumoxidereactswithdilutesodiumhydroxidetoformasaltandoneotherproduct.

Name the other product.

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

(iv) Aluminiumhydroxide,Al (OH)3,decomposeswhenheatedtoformaluminiumoxideandwater.

Write the chemical equation for this reaction.

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

(v) Suggest the names of two other aluminium compounds that decompose when heated to formaluminiumoxide.

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

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

[Total: 19]

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3 ThePeriodicTableisamethodofclassifyingelements.

(a) IdentifytheelementwhichisinGroupVIandPeriod4.

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

(b) CalciumisinGroupIIandchlorineisinGroupVIIofthePeriodicTable.

Explain,intermsofnumberofoutershellelectronsandelectrontransfer,howcalciumatomsand chlorine atoms form ions. Give the formulae of the ions formed.

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

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

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

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

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

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

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

(c) GroupVchloridesarecovalentmolecules.TheboilingpointsofsomeGroupVchloridesareshown.

chloride boiling point / °C

NCl 3 71

PCl 3AsCl 3 130

SbCl 3 283

(i) SuggesttheapproximateboilingpointofPCl 3.

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

(ii) Explainthetrendinboilingpointsintermsofattractiveforcesbetweenparticles.

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

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

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(iii) Completethedot-and-crossdiagramtoshowtheelectronarrangementinamoleculeofPCl 3.

Showouterelectronsonly.

P

Cl

ClCl

[3]

(d) PCl 3 reacts with chlorine, Cl 2, to form PCl 5. This reaction is exothermic and reaches anequilibrium.

PCl 3(g)+Cl 2(g) PCl 5(g)

(i) Describe two features of an equilibrium.

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

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

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

(ii) Statetheeffect,ifany,onthepositionofthisequilibriumwhenthefollowingchangesaremade.

Explainyouranswers.

temperature is increased ....................................................................................................

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

pressure is increased .........................................................................................................

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

(iii) Explain,intermsofparticles,whathappenstotherateoftheforwardreactionwhenthereactionmixtureisheated.

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

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

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

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

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

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(e) PCl 5reactswithlithiumfluoride,LiF,toformLiPF6.

PCl 5+6LiF→LiPF6+5LiCl

CalculatethemassofLiFneededtoform3.04gofLiPF6 using the following steps.

● CalculatethenumberofmolesofLiPF6 formed. [Mr:LiPF6,152]

number of moles = ..............................

● DeducethenumberofmolesofLiFneeded.

number of moles = ..............................

● CalculatethemassofLiFneeded.

mass = .............................. g [3]

(f) Lithiumfluoridehasionicbonding.

(i) What is an ionic bond?

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

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

(ii) Give twophysicalpropertiesofioniccompounds.

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

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

[Total: 28]

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4 Ironisatypicaltransitionelement.

Iron: ● actsasacatalyst ● forms coloured compounds ● hasmorethanoneoxidationstate.

(a) Name onemajorindustrialprocessthatusesironasacatalystandnametheproductmadeinthis process.

process ......................................................................................................................................

product made ............................................................................................................................. [2]

(b) Whenaqueoussodiumhydroxideisaddedtoaqueousiron(II)sulfate,aprecipitateforms.

(i) What colour is this precipitate?

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

(ii) Writetheionicequationforthisreaction.Includestatesymbols.

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

(c) Iron(II) sulfate can be converted to iron(III) sulfatebypotassiummanganate(VII) at room temperature.

(i) What is the role of potassium manganate(VII) in this reaction?

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

(ii) What condition must be used for this reaction to occur?

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

(iii) Intermsofelectrontransfer,whathappenstotheiron(II) ions in this reaction?

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

(iv) State the colour change seen during this reaction.

from purple to ............................................................................................................... [1]

(d) Deduce the charge on the iron ion in each of these compounds.

FeF3 ...........................................................................................................................................

Fe(NO3)3 .................................................................................................................................... [2]

[Total: 12]

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5 Therearetwotypesofpolymers.

(a) Additionpolymersaremadefrommanyidenticalsmallunits.

(i) What is the term used to describe these small units?

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

(ii) Asectionofanadditionpolymerisshown.

C

H

H

C

CH3

CH3

C

H

H

C

CH3

CH3

C

H

H

C

CH3

CH3

Drawthestructureofthesmallunitusedtomakethisadditionpolymer.

Show all of the atoms and all of the bonds.

[2]

(b) Polyamidesarecondensationpolymers.

What does the term condensationmeanwhenusedtodescribethistypeofpolymer?

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

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To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cambridgeinternational.org after the live examination series.

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

(c) Apolyamidecanbemadefromtwodifferentmolecules.

Asimplifiedstructureofoctanedioicacidisshown.

C C

OO

O O HH

Asimplifiedstructureof1,6-diaminohexaneisshown.

N N

HH

HH

(i) Completethediagramtoshowasectionofpolyamidemanufacturedfromoctanedioicacidand1,6-diaminohexane.Includealloftheatomsandallofthebondsinthelinkages.

[3]

(ii) Statethenameofasyntheticpolyamide.

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

[Total: 8]

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Gro

up

The

Perio

dic

Tabl

e of

Ele

men

ts

1 Hhy

drog

en1

2 He

heliu

m4

III

IIIIV

VV

IV

IIV

III

3 Lilit

hium 7

4 Be

bery

llium

9

atom

ic n

umbe

r

atom

ic s

ymbo

l

Key

nam

ere

lativ

e at

omic

mas

s

11 Na

sodi

um23

12 Mg

mag

nesi

um24

19 Kpo

tass

ium

39

20 Ca

calc

ium

40

37 Rb

rubi

dium

85

38 Sr

stro

ntiu

m88

55 Cs

caes

ium

133

56 Ba

bariu

m13

7

87 Frfra

nciu

m–

88 Ra

radi

um –

5 B boron 11 13 Al

alum

iniu

m27 31 Ga

galli

um70 49 In indi

um11

5

81 Tlth

alliu

m20

4

6 Cca

rbon

12 14 Si

silic

on28 32 Ge

germ

aniu

m73 50 Sn tin 119 82 Pb

lead

207

22 Titit

aniu

m48 40 Zr

zirc

oniu

m91 72 Hf

hafn

ium

178

104

Rf

ruth

erfo

rdiu

m–

23 Vva

nadi

um51 41 Nb

niob

ium

93 73 Tata

ntal

um18

1

105

Db

dubn

ium

–

24 Cr

chro

miu

m52 42 Mo

mol

ybde

num

96 74 Wtu

ngst

en18

4

106

Sg

seab

orgi

um–

25 Mn

man

gane

se55 43 Tc

tech

netiu

m– 75 Re

rhen

ium

186

107

Bh

bohr

ium

–

26 Fe iron

56 44 Ru

ruth

eniu

m10

1

76 Os

osm

ium

190

108

Hs

hass

ium

–

27 Co

coba

lt59 45 Rh

rhod

ium

103

77 Iriri

dium

192

109

Mt

mei

tner

ium

–

28 Ni

nick

el59 46 Pd

palla

dium

106

78 Pt

plat

inum

195

110

Ds

darm

stad

tium

–

29 Cu

copp

er64 47 Ag

silv

er10

8

79 Au

gold

197

111

Rg

roen

tgen

ium

–

30 Zn zinc

65 48 Cd

cadm

ium

112

80 Hg

mer

cury

201

112

Cn

cope

rnic

ium

–

114 Fl

flero

vium

–

116

Lvliv

erm

oriu

m–

7 Nni

troge

n14 15 P

phos

phor

us31 33 As

arse

nic

75 51 Sb

antim

ony

122

83 Bi

bism

uth

209

8 Oox

ygen

16 16 S sulfur

32 34 Se

sele

nium

79 52 Tete

lluriu

m12

8

84 Po

polo

nium

–

9 Fflu

orin

e19 17 Cl

chlo

rine

35.5

35 Br

brom

ine

80 53 Iio

dine

127

85 At

asta

tine

–

10 Ne

neon 20 18 Ar

argo

n40 36 Kr

kryp

ton

84 54 Xe

xeno

n13

1

86 Rn

rado

n–

21 Sc

scan

dium

45 39 Yyt

trium 89

57–7

1la

ntha

noid

s

89–1

03ac

tinoi

ds

57 Lala

ntha

num

139

89 Ac

lant

hano

ids

actin

oids

The

volu

me

of o

ne m

ole

of a

ny g

as is

24

dm3 a

t roo

m te

mpe

ratu

re a

nd p

ress

ure

(r.t.p

.).

actin

ium

–

58 Ce

ceriu

m14

0

90 Th thoriu

m23

2

59 Pr

pras

eody

miu

m14

1

91 Pa

prot

actin

ium

231

60 Nd

neod

ymiu

m14

4

92 Uur

aniu

m23

8

61 Pm

prom

ethi

um– 93 Np

nept

uniu

m–

62 Sm

sam

ariu

m15

0

94 Pu

plut

oniu

m–

63 Eu

euro

pium

152

95 Am

amer

iciu

m–

64 Gd

gado

liniu

m15

7

96 Cm

curiu

m–

65 Tb terbiu

m15

9

97 Bk

berk

eliu

m–

66 Dy

dysp

rosi

um16

3

98 Cf

calif

orni

um–

67 Ho

holm

ium

165

99 Es

eins

tein

ium

–

68 Er

erbi

um16

7

100

Fm fermiu

m–

69 Tm thuliu

m16

9

101

Md

men

dele

vium

–

70 Yb

ytte

rbiu

m17

3

102

No

nobe

lium

–

71 Lu lutetiu

m17

5

103 Lr

law

renc

ium

–