Mark Schemes Summer 2008 GCSE...2008/08/07 · 1. 4335-1F Mark Scheme 1 2.4335-2H Mark Scheme 11...

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Mark Schemes Summer 2008

IGCSE

IGCSE Chemist ry (4335)

Edexcel Limit ed. Regist ered in England and Wales No. 4496750 Regist ered Of f ice: One90 High Holborn, London WC1V 7BH

ii

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Summer 2008

Publ icat ions Code UG020251

Al l t he mat erial in t his publ icat ion is copyright

© Edexcel Lt d 2008

iii

Contents

1. 4335-1F Mark Scheme 1

2. 4335-2H Mark Scheme 11

3. 4335-03 Mark Scheme 19

-1-

4335 IGCSE Chemistry Summer 2008

IGCSE CHEMISTRY 4335-1F MARK SCHEME

Quest ion

Number

Correct Answer Accept able

Answers

Rej ect Mark

1 (a)

second box

(1)

Quest ion

Number


Answers

Rej ect Mark

1 (b)(i)

t op box

(1)

Quest ion

Number


Answers

Rej ect Mark

1 (b)(ii)

middle box

(1)

Quest ion

Number


Answers

Rej ect Mark

1 (c)(i)

made up of / cont ains only one t ype of

at om

or

somet hing t hat cannot be broken

down by chemical means

(1)

Quest ion

Number


Answers

Rej ect Mark

1 (c)(ii)

t hree/ 3

(1)

(Total 5 marks)

Quest ion

Number


Answers

Rej ect Mark

2 (a)(i)

magnesium

(1)

Quest ion

Number


Answers

Rej ect Mark

2 (a)(ii)

gold

(1)

Quest ion

Number


Answers

Rej ect Mark

2 (b)(i)

magnesium/ zinc is more react ive t han

iron

OR

magnesium displaces iron

(1)

-2-


Quest ion

Number


Answers

Rej ect Mark

2 (b)(ii)

zinc sulphat e AND iron

(1)

Quest ion

Number


Answers

Rej ect Mark

2 (c)(i)

bulb / ammet er/ buzzer

(1)

Quest ion

Number


Answers

Rej ect Mark

2 (c)(ii)

ions

(1)

(Total 6 marks)

Quest ion

Number


Answers

Rej ect Mark

3 (a)(i)

l ight ed spil l

pop (dependent on correct t est )

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (a)(ii)

sodium hydroxide

(1)

Quest ion

Number


Answers

Rej ect Mark

3 (a)(iii)

green

blue/ purple

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (b)

loses

gains (give one mark if t he f irst t wo are

t he wrong way round)

high

st rong (dependent on having high

correct )

1

1

1

1

(4)

(Total 9 marks)

-3-


Quest ion

Number


Answers

Rej ect Mark

4 (a)(i)

bit umen

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (a)(ii)

ref inery gases

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (a)(iii)

gasol ine

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (b)

kerosene

diesel/ gasol ine/ ref inery gases

bit umen

1

1

1

(3)

Quest ion

Number


Answers

Rej ect Mark

4 (c)(i)

oxygen on lef t

wat er on right

carbon dioxide on right

1

1

1

(3)

Quest ion

Number


Answers

Rej ect Mark

4 (c)(ii)

carbon monoxide

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (c)(iii)

carbon

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (d)(i)

giant

momomers

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

4 (d)(ii)

middle box

(1)

(Total 14 marks)

-4-


Quest ion

Number


Answers

Rej ect Mark

5 (a)(i)

f i f t h / last box

(1)

Quest ion

Number


Answers

Rej ect Mark

5 (a)(ii)

A E C D – ful ly correct get s t hree

marks.

If not ful ly correct t hen (t o a

maximum of t wo):

bot h A and E before C – 1 mark

D direct ly af t er C – 1 mark

E direct ly before C – 1 mark

(3)

Quest ion

Number


Answers

Rej ect Mark

5 (a)(iii)

heat / warm

(1)

Quest ion

Number


Answers

Rej ect Mark

5 (b)(i)

yel low

(1)

Quest ion

Number


Answers

Rej ect Mark

5 (b)(ii)

red

(1)

Quest ion

Number


Answers

Rej ect Mark

5 (b)(iii)

neut ral isat ion

(1)

Quest ion

Number


Answers

Rej ect Mark

5 (b)(iv)

wat er

(1)

(Total 9 marks)

Quest ion

Number


Answers

Rej ect Mark

6 (a)

f irst box: nit rogen

second box: oxygen

t hird box: argon; carbon dioxide.

one mark per gas in correct box. If

gas used t wice t hen no mark for t hat

gas.

(4)

-5-


Quest ion

Number


Answers

Rej ect Mark

6 (b)(i)

black

(1)

Quest ion

Number


Answers

Rej ect Mark

6 (b)(ii)

CuO

(1)

Quest ion

Number


Answers

Rej ect Mark

6 (c)(i)

t op box: hydrochloric acid

bot t om box: calcium carbonat e

(2)

Quest ion

Number


Answers

Rej ect Mark

6 (c)(ii)

l imewat er/ calcium hydroxide

(solut ion)

(1)

Quest ion

Number


Answers

Rej ect Mark

6 (c)(iii)

f ire ext inguisher / f izzy drinks / dry

ice as coolant or st age ef fect s

(1)

Quest ion

Number


Answers

Rej ect Mark

6 (d)(i)

carbon

(1)

Quest ion

Number


Answers

Rej ect Mark

6 (d)(ii)

magnesium

(1)

(Total 12 marks)

Quest ion

Number


Answers

Rej ect Mark

7 (a)(i) elect rolysis

(1)

Quest ion

Number


Answers

Rej ect Mark

7 (a)(ii) graphit e / carbon

(1)

-6-


Quest ion

Number


Answers

Rej ect Mark

7 (a)(iii) – on lef t and + on right

(1)

Quest ion

Number


Answers

Rej ect Mark

7 (a)(iv) aluminium oxide / alumina

cryol it e

accept

correct

formulae

ignore

bauxit e

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

7 (a)(v) elect ricit y (ignore qual if icat ions) /

elect rical energy (not energy

alone)

Anode/

posit ive

elect rode

replacement

Cat hode

/ elect rode

replacement

(1)

Quest ion

Number


Answers

Rej ect Mark

7 (b)(i) oxygen

(1)

Quest ion

Number


Answers

Rej ect Mark

7 (b)(ii) • carbon dioxide / carbon monoxide

• graphit e/ carbon/ elect rode

oxidised/ burned/ react s wit h

oxygen

accept

correct

formulae

(ignore

lower case)

l ist s

equat ion

1

1

(2)

(Total 9 marks)

Quest ion

Number


Answers

Rej ect Mark

8 (a)(i) Any t wo f rom:

• same or similar chemical

propert ies / same funct ional group

• gradat ion in physical propert ies

• neighbouring/ successive members

dif fer by CH2

Gradat ion of

specif ied

physical

propert y (eg:

boil ing

point / bp(t ),

melt ing

point / mp(t ),

viscosit y)

NOT a

specif ied

chemical

propert y

dif ferent /

same

physical

propert ies (2)

-7-


Quest ion

Number


Answers

Rej ect Mark

8 (a)(ii) alkene

(1)

Quest ion

Number


Answers

Rej ect Mark

8 (a)(iii) CnH2n Any ot her

let t er in place

of “ n”

(1)

Quest ion

Number


Answers

Rej ect Mark

8 (b)(i) • (H) one elect ron shown

• (C) t wo elect rons in f irst shel l and

four in second shel l

Accept any

symbol for

elect rons.

Elect rons

on nucleus

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

8 (b)(ii) • al l f ive at oms and four shared pairs

of elect rons

• no ext ra out er elect rons.

IGNORE inner

elect rons

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

8 (b)(iii) t et rahedral

(1)

Quest ion

Number


Answers

Rej ect Mark

8 (c)(i) • (compounds wit h) same molecular

formula

• (but ) dif ferent st ruct ural formulae

/ displayed formula/ st ruct ure /

at oms arranged dif ferent ly

(same) element s = 0 marks

Mark

independent ly

same

chemical

formula

Rej ect

subst ances

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

8 (c)(ii) Correct st ruct ures of but ane and

met hylpropane. ALL bonds shown

Penal ise st icks wit h missing H once

only

1

1

(2)

(Total 13 marks)

-8-


Quest ion

Number


Answers

Rej ect Mark

9 (a)(i) 2

(1)

Quest ion

Number


Answers

Rej ect Mark

9 (a)(ii) 2.8.2

(1)

Quest ion

Number


Answers

Rej ect Mark

9 (b)(i) any t wo f rom

• ef fervescence / f izzing / bubbles

• cloudiness / whit e precipit at e

/ milky / whit e suspension

• Ca get smaller / disappears (ignore

dissolves).

• Ca moves up and down

Ignore gas

made

ignore

f loat s/ moves

List

(2)

Quest ion

Number


Answers

Rej ect Mark

9 (b)(ii) Ca(OH)2

(1)

Quest ion

Number


Answers

Rej ect Mark

9 (b)(iii) • blue

• alkal i / OH- / hydroxide / pH >7

(ignore base)

• st at ed pH value in range 8-14

purple 1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

9 (c)(i) • grey / si lver(y)

• whit e

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

9 (c)(ii) any t wo f rom

• over/ t hrough wat er / downward

displacement of wat er

• (gas) syringe

• upward del ivery / downward

displacement of air

a descript ion

of t his

suit able

diagrams

gas cyl inder

(2)

-9-


Quest ion

Number


Answers

Rej ect Mark

9 (c)(iii) hydrogen + oxygen → wat er / st eam ignore heat formulae

(1)

(Total 12 marks)

Quest ion

Number


Answers

Rej ect Mark

10 (a)(i) ammonia / NH3 Ammonium

NH4 (1)

Quest ion

Number


Answers

Rej ect Mark

10 (a)(ii) chloride / Cl-

Chlorine

Cl

Cl2 (1)

Quest ion

Number


Answers

Rej ect Mark

10 (a)(iii) copper(II) / Cu2+

/ copper / cupric cupper Copper(I)

Cuprous

Cu+ (1)

Quest ion

Number


Answers

Rej ect Mark

10 (a)(iv) iron(II) / Fe2+

/ ferrous Fe3+

Ferric

Iron (1)

Quest ion

Number


Answers

Rej ect Mark

10 (b)(i) CuSO4 / copper((II)) sulphat e

(1)

Quest ion

Number


Answers

Rej ect Mark

10 (b)(ii) • KNO3 / pot assium nit rat e

• l i lac (dependent on correct

compound)

OR

• CuSO4 / copper((II)) sulphat e

• green / blue-green (dependent on

correct compound)

pot assium/ C

pink

copper/ B

Purple

blue

(2)

-10-


Quest ion

Number


Answers

Rej ect Mark

10 (c)(i) yel low precipitate/ ppt/ ppte suspension

(1)

Quest ion

Number


Answers

Rej ect Mark

10 (c)(ii) AgNO3(aq) + LiI(aq) → AgI(s) + LiNO3(aq)

LiI(aq) + AgNO3(aq)

formulae of product s

st at e symbols of product s (dependent on

correct product formulae)

i f al l correct

but balanced

wrongly, award

2 marks

(3)

(Total 11 marks)

PAPER TOTAL 100 MARKS

-11-


IGCSE CHEMISTRY 4335-2H MARK SCHEME

Quest ion

Number


Answers

Rej ect Mark

1 (a)(i) elect rolysis

(1)

1 (a)(ii) graphit e / carbon

(1)

1 (a)(iii) – on lef t and + on right

(1)

1 (a)(iv) aluminium oxide / alumina

cryol it e

accept correct

formulae

ignore bauxit e

1

1

(2)

1 (a)(v) elect ricit y (ignore qual if icat ions)

/ elect rical energy (not energy

alone)

anode/ posit ive

elect rode

replacement

cat hode

/ elect rode

replacement (1)

1 (b)(i) oxygen

(1)

1 (b)(ii) • carbon dioxide / carbon

monoxide

• graphit e/ carbon/ elect rode

oxidised/ burned/ react s wit h

oxygen

accept correct

formulae (ignore

lower case)

l ist s

equat ion

1

1

(2)

9

2 (a)(i) Any t wo f rom:

• same or similar chemical

propert ies / same funct ional

group

• gradat ion in physical propert ies

• neighbouring/ successive

members dif fer by CH2

gradat ion of

specif ied physical

propert y (eg:

boil ing

point / bp(t ),

melt ing

point / mp(t ),

viscosit y)

NOT a

specif ied

chemical

propert y

dif ferent /

same

physical

propert ies

(2)

2 (a)(ii) alkene

(1)

2 (a)(iii) CnH2n any ot her let t er

in place of “ n”

(1)

2 (b)(i) • (H) one elect ron shown

• (C) t wo elect rons in f irst shel l

and four in second shel l

aAccept any

symbol for

elect rons.

elect rons on

nucleus

1

1

(2)

2 (b)(ii) • al l f ive at oms and four shared

pairs of elect rons

• no ext ra out er elect rons.

IGNORE inner

elect rons

1

1

(2)

2 (b)(iii) t et rahedral

(1)

-12-


Quest ion

Number


Answers

Rej ect Mark

2 (c)(i) • (compounds wit h) same

molecular formula

• (but ) dif ferent st ruct ural

formulae / displayed

formula/ st ruct ure / at oms

arranged dif ferent ly

(same) element s = 0 marks

mark

independent ly

same

chemical

formula.

Rej ect

subst ances.

1

1

(2)

2 (c)(ii) Correct st ruct ures of but ane and

met hylpropane. ALL bonds shown

Penal ise st icks wit h missing H

once only

1

1

(2)

13

3 (a)(i) 2

(1)

3 (a)(ii) 2.8.2

(1)

3 (b)(i) any t wo f rom

• ef fervescence / f izzing /

bubbles

• cloudiness / whit e precipit at e

/ milky / whit e suspension

• Ca get smaller / disappears

(ignore dissolves).

• Ca moves up and down

ignore gas made

ignore

f loat s/ moves

List

(2)

3 (b)(ii) Ca(OH)2

(1)

3 (b)(iii) • blue

• alkal i / OH- / hydroxide / pH >7

(ignore base)

• st at ed pH value in range 8-14

purple 1

1

(2)

3 (c)(i) • grey / si lver(y)

• whit e

1

1

(2)

3 (c)(ii) any t wo f rom

• over/ t hrough wat er / downward

displacement of wat er

• (gas) syringe

• upward del ivery / downward

displacement of air

a descript ion of

t his

suit able diagrams

gas cyl inder

(2)

3 (c)(iii) hydrogen + oxygen → wat er /

st eam

ignore heat formulae

(1)

12

4 (a)(i) ammonia / NH3 ammonium

NH4 (1)

-13-


Quest ion

Number


Answers

Rej ect Mark

4 (a)(ii) chloride / Cl-

chlorine

Cl

Cl2 (1)

4 (a)(iii) copper(II) / Cu2+

/ copper / cupric cupper copper(I)

cuprous

Cu+ (1)

4 (a)(iv) iron(II) / Fe2+

/ ferrous Fe3+

ferric

iron (1)

4 (b)(i) CuSO4 / copper((II)) sulphat e

(1)

4 (b)(ii) • KNO3 / pot assium nit rat e

• l i lac (dependent on correct

compound)

OR

• CuSO4 / copper((II)) sulphat e

• green / blue-green (dependent

on correct compound)

pot assium/ C

pink

copper/ B

purple

blue

(2)

4 (c)(i) yel low precipitate/ ppt/ ppte suspension

(1)

4 (c)(ii) AgNO3(aq) + LiI(aq) → AgI(s) +

LiNO3(aq)

LiI(aq) + AgNO3(aq)

formulae of product s

st at e symbols of product s

(dependent on correct product

formulae)

i f al l correct but

balanced

wrongly, award 2

marks

(3)

11

5 (a)(i) dif fusion

(1)

5 (a)(ii) • ment ion of part icles (if part icles

named, must be correct ) in

correct cont ext

• moving (randomly)

(accept

molecules/ ions)

move (f rom high

t o low

concent rat ion)

1

1

(2)

5 (b)(i) • (blue) ppt – colour not needed

but penal ise ppt if colour is

wrong

• deep/ dark/ royal blue

• solut ion / dissolves

ignore changes t o

colour of solut ion

dark/ royal/

deep blue

ppt

1

1

1

(3)

5 (b)(ii) [Cu(H2O)2(NH3)4]2+

/

[Cu(NH3)4(H2O)2]2+

formulae wit hout

[ ]

(1)

7

-14-


Quest ion

Number


Answers

Rej ect Mark

6 (a)(i) Any t hree f rom

• f loat / on surface

• f izz/ bubble (ignore gas)

• move/ dart about

• melt / form sphere/ bal l

• Na get s smaller / disappears

(ignore dissolves)

ignore references

t o f lames /

ignit ing

(3)

6 (a)(ii) 2Na + 2H2O 2 NaOH + H2

• correct formulae

• balancing (dependent on f irst

mark being awarded)

Na(OH)

any mult iple

(2)

6 (a)(iii) Moves/ bubbles fast er/ (more)

violent / more vigorous/ cat ches

f ire/ f lame/ explodes

react ion

fast er/ i t is

fast er (1)

6 (b)(i) • sodium loses elect ron(s)

• oxygen gains elect rons

• correct number of elect rons for

each at om

marks could be gained by

suit able addit ions t o print ed

diagram

indicat ion of 2 Na

and 1 O

any

reference t o

sharing

/ covalent

gives O

(3)

6 (b)(ii) • st rong at t ract ive forces / bonds

(regardless of what t hese are

bet ween)

• bet ween ions

• require a lot of energy t o

overcome / dif f icul t t o break

(regardless of what t hese are

bet ween)

second mark

not given if

at oms /

molecules /

int ermolecul

ar

1

1

1

(3)

6 (b)(iii) • st ronger at t ract ive forces /

bonding

• magnesium ion 2+, sodium ion

1+ / magnesium loses 2 elect rons,

sodium loses 1

elect ron/ magnesium ions are

smaller or have bigger charge or

are more highly charged (must

st at e or imply comparison

bet ween Mg and Na)

ignore more

bonds/

int ermolecular

forces

MgO Covalent

= 0

delocal ised

elect rons = 0

1

1

(2)

14

-15-


Quest ion

Number


Answers

Rej ect Mark

7 (a) any f ive f rom:

• add magnesium carbonat e t o

acid

• st ir/ mix

• excess magnesium carbonat e

• f i l t er / cent rifuge and decant

• heat or evaporat e f i l t rat e and

st op evaporat ion at a suit able

point / heat f i l t rat e and leave t o

cool / leave f i l t rat e t o evaporat e

or t o cryst al l ise or for suit able

t ime / place in oven below 100 °C

• dry cryst als wit h (f i l t er) paper

/ desiccat or

Ignore indicat ors

• If use sodium

carbonat e (or

ot her soluble

carbonat e)only

point s 2,5,6

• If use ot her

insoluble

carbonat e, al l

bar f irst point .

• Wrong met hod

of prep. Then get

5 and 6 only.

heat t o

dryness, can

not get 5 or 6

(5)

7 (b)(i) • colourless

• t o pink

i f j ust st at e

“ pink” wit h no

st art colour, t hen

score 1

purple / red

1

1

(2)

7 (b)(ii)

• 0.150 x 0.00870

• =0.00131 correct answer scores

2

(moles)

incorrect or

fai lure t o convert

volume t o dm3

gives max 1

accept 2 t o 4 sig

f igs

(0.001305)

wrong

numbers

used = 0

1

1

(2)

7 (b)(iii) (i i) ÷ 2 = 0.000653

(moles)

cq on b(i i)

accept 2 t o 4 sig

f igs

(0.006525)

(1)

7 (b)(iv) (i i i) ÷ 0.025 = 0.0261

(mol dm-3

)

cq on b(i i i )

accept 2 t o 4 sig

f igs

(0.02612)

(1)

11

8 (a)(i) • add (named) acid

• bubbles/ ef fervescence/ f izzing

OR gas produced t urns l imewat er

milky

2nd

mark possible

only if acid

added

1

1

(2)

8 (a)(ii) 2NaOH + CO2 Na2CO3 + H2O

formulae = 1

balancing = 1 (only if f ormulae

correct )

accept any

mult iple

(2)

8 (b) • no change / remains clear

• carbon dioxide react ed

/ removed(by sodium hydroxide) /

formed sodium carbonat e /

1

1

(2)

-16-


Quest ion

Number


Answers

Rej ect Mark

8 (c)(i) • Mr NaHCO3 = 84

• moles = 4.2 ÷ 84

• = 0.05(0) ignore any unit s

Correct answer scores 3

If Mr incorrect , max 2 (107 gives

0.039; 168 gives 0.025)

1

1

1

(3)

8 (c)(ii) (i) ÷ 2 = 0.025

ignore any unit s

cq

(1)

8 (c)(iii) (i i) x 24 (dm3) =0.6 unit not

required but penal ise incorrect

unit s.

cq answer in

cm3

(1)

11

9 (a) any in range 40 t o 100

(1)

9 (b)(i) H2 + Cl2 2HCl

formulae = 1

balancing = 1 (only if f ormulae

correct ) accept any mult iples

CL

(2)

9 (b)(ii) wat er:

• paper becomes red (NOT

orange)

• acidic / H+ ions produced

met hylbenzene:

• no change / orange

• no H+ ions formed / not acidic

/ does not ionise (indep. of

colour)

red/ orange

ignore refs t o

being neut ral

orange

Ionizes alone

green

references t o

acidit y of

met hyl

benzene

1

1

1

1

(4)

7

10 (a)(i) galvanising / sacrif icial

prot ect ion

(1)

10 (a)(ii) rai l ings / cars / bridges / bucket s

/ wat ering cans / lamp post s et c.

accept

ships/ boat s even

t hough zinc

blocks and not a

cont inuous layer

used

bikes

(1)

10 (a)(iii) • zinc more react ive (t han iron)

• zinc react s/ corrodes/ oxidises in

preference t o / before / inst ead of

iron

It is more

react ive t han

iron

It is more

react ive

zinc rust s

prot ect ive

coat ing of

zinc oxide

1

1

(2)

-17-


Quest ion

Number


Answers

Rej ect Mark

10 (b) • make solut ion of nickel nit rat e

• add met al

• i f react ion occurs t hen met al is

more react ive t han nickel

OR

• work down f rom t op of l ist unt i l

no react ion occurs / work up

f rom bot t om of l ist unt i l react ion

does occur.

displacement

react ion wit hout

making a solut ion

is max 2

react ion wit h

anyt hing else

(such as

HCl(aq)) is

zero

react wit h

met al (for 2nd

mark)

1

1

1

(3)

10 (c)(i) Reduced because gain of

elect rons

reduced because

oxidat ion st at e

decreases

(1)

10 (c)(ii) • Q=1.5 x 160 = 240(coulombs)

• Faradays = 240÷96000 = 0.0025

(cq)

• Moles Ni = 0.0025÷2 = 0.00125

(cq)

• mass Ni = 0.00125 x 59 = 0.074

(g) (0.0737 or 0.07375) (cq).

(0.0025 x 59 is max 3) unit s not

required

Final answer correct = 4 marks

Accept 2 or more

sig f igs (1 sig f ig

max 3)

Accept use of

96500

0.00249

0.001245

0.07337

incorrect use

of kg or mg

1

1

1

1

(4)

12

11 (a)(i) • appropriat e cat alyst

alumina/ aluminium oxide/ porous

pot / (conc) phosphoric acid / conc

sulphuric acid. )

• heat / high t emperat ure

ignore references

t o pressure

150 – 1000oC

aluminium 1

1

(2)

11 (a)(ii) • correct energy level for

endot hermic (higher) and one

f rom

• product s marked wit h correct

names/ formulae

Mark independent ly

Ignore any

act ivat ion

energies shown

1

1

(2)

11 (a)(iii) • Increased

• endot hermic (lef t t o right ) or

descript ion of endot hermic / ΔH

is posit ive

ignore references

t o rat e

if decreased

or st ays t he

same = zero

1

1

(2)

-18-


Quest ion

Number


Answers

Rej ect Mark

11 (b)

• correct st ruct ure wit h minimum

4 carbons

• cont inuat ion bonds shown (not

j ust dot s) (bracket s not required)

Ignore “ n”

subscript s

any st ruct ure

wit h C=C or

based on

wrong repeat

unit = 0

1

1

(2)

11 (c) If calculat e empirical f irst :

• Correct empirical formula wit h

some correct working = 3

division

by Ar

38.7/ 12

= 3.23

9.70/ 1

= 9.70

51.6 /

16 =

3.23

division

by

smallest

3.23 /

3.23 = 1

9.70 /

3.23 = 3

3.23 /

3.23 = 1

empiric

al

CH3O

• Correct molecular formula (wit h

any correct working)= 2

mass of empirical 31

molecular C2H6O2

If calculat e molecular f irst

mass of

each

element

38.7 x

.62 = 24

9.70 x

62 = 6

51.6 x

.62 = 32

division

by Ar

24 / 12

= 2

6 / 1 =

6

32 / 16

= 2

C2H6O2

correct molecular wit h some

working = 3

Correct empirical = 2

If Ar incorrect /

use Z in place of

Ar t hen lose f irst

mark

If NO working

shown, t hen max

1 each for t he

t wo answers

regardless of

order of answers

If f irst st ep

t ot al ly

wrong, zero.

1

1

1

2

1

1

1

2

(5)

13


-19-


IGCSE CHEMISTRY 4335-03 MARK SCHEME

Quest ion

Number


Answers

Rej ect Mark

1 (a)

B

E

D

F

b

e

d

f

Any ot her

answers

1

1

1

1

(4)

Quest ion

Number


Answers

Rej ect Mark

1 (b)

F

A

C

f

a

c

Any ot her

answers

(1)

(Total 5 marks)

Quest ion

Number


Answers

Rej ect Mark

2 (a) 22.65

1.30 (zero needed for mark)

21.35

1

1

1

(3)

Quest ion

Number


Answers

Rej ect Mark

2 (b) (i) t icks under 23.10 and 23.20

(1)

Quest ion

Number


Answers

Rej ect Mark

2 (b) (i i) 23.10 + 23.20

2

23.15 (answer must be t o 2 dp)

1

1

(2)

(Total 6 marks)

-20-


Quest ion

Number


Answers

Rej ect Mark

3 (a) mass / weight / amount / number of

moles

(surface) area / size (of chips)

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (b) (i) 3

did not do experiment for 1 minut e

/ did not record t ime

/ wait ed for bubbles t o st op

/ wait ed for react ion t o end

OWTTE

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (b) (i i) t wo correct column headings:

concent rat ion (of acid)

mass of gas lost / given of f

carbon dioxide/ CO2

t wo correct unit s:

%

g / grams

weight

amount

1

1

Quest ion

Number


Answers

Rej ect Mark

3 (b) (i i) six values correct ly insert ed 2

(4)

Quest ion

Number


Answers

Rej ect Mark

3 (c) (i) vert ical scale of 1 cm rep 0.1 g

six point s correct ly plot t ed

(st raight ) l ine of best f i t ignoring

anomalous point

1

2

1

(4)

-21-


Quest ion

Number


Answers

Rej ect Mark

3 (c) (i i) 0.44 / 50 circled or ot herwise ident if ied 1

(1)

Quest ion

Number


Answers

Rej ect Mark

3 (c) (i i i) cot t on wool not put in f lask/

acid (spray)

escaped

acid t oo concent rat ed / t oo much acid

t emperat ure t oo high

gas col lect ed for longer t han 1 minut e

malachit e pieces smaller /

bigger surface area

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (c) (iv) vert ical l ine f rom 70 % t o l ine of best f i t

0.47

bet ween

0.46 and

0.48

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (d) (i) mass (of CO2 given of f ) increases as

concent rat ion (of acid) increases /

mass (of CO2 given of f ) decreases as

concent rat ion (of acid) decreases

direct proport ion / equivalent wording

such as "mass doubles when

concent rat ion doubles"

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

3 (d) (i i) more col l isions bet ween part icles /

equivalent wording such as "part icles

bump int o each ot her more"

correct reference t o f requency or t ime,

eg "col l isions are more f requent ",

part icles bump int o each ot her more

of t en", "more col l isions in a given t ime"

references

t o energy

1

1

(2)

(Total 21 marks)

-22-


Quest ion

Number


Answers

Rej ect Mark

4 (a)(i)

40.5 40,5

40.50

40,50

Any

ot her

answers

(1)

Quest ion

Number


Answers

Rej ect Mark

4 (a)(ii)

10.5

16.8

10.50

16.80

Any ot her

answers

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

4 (a)(iii)

100 × 10.5

16.8

62.5

cq on 4(a)(i i)

1

1

(2)

Quest ion

Number


Answers

Rej ect Mark

4 (b) (i)

six point s correct ly plot t ed

smoot h curve of best f i t

2

1

(3)

Quest ion

Number


Answers

Rej ect Mark

4 (b) (i i) SEE NOTES

(1)

Notes • If a vert ical l ine is drawn f rom t he int ersect ion (wit hin 1 small

square), t hen award mark if t he answer is wit hin 1 ºC

• If no vert ical l ine drawn f rom t he int ersect ion, t hen decide what t he

answer should be, and award mark if wit hin 1ºC

• Ignore ° C

Quest ion

Number

Correct

Answer

Accept able Answers Rej ect Mark

4 (c)

(solubil i t y)

st ays t he

same

increase(d)

decrease(d)

Any ot her answers wit h t he same

meaning, eg for "st ays t he same",

accept

unchanged, does not change,

remains const ant

eg for "increased", accept

bigger, great er, larger, more

eg for "decreased", accept

smaller, less, lower

1

1

1

(3)

-23-


Quest ion

Number


Answers

Rej ect Mark

4 (d)(i)

add ice (t o t he beaker or

wat er)

/ cool t he wat er in a

f r idge

use wat er f rom

f ridge

put t ube in ice

add ice t o t ube

add ice t o mixt ure

add ice t o salt

add ice t o solut ion

do experiment in

f r idge

do experiment in

cold room

(1)

Quest ion

Number

Correct Answer Accept able Answers Rej ect Mark

4 (d)(ii)

wat er boils at 100

(° C)

/ (120 ° C is) above

boil ing point of

wat er

Any answer wit h same

meaning, eg

boil ing point of wat er is 100

° C

t his t emperat ure is higher

t han t he boil ing point of

wat er

Accept boil ing t emperat ure,

bp and bpt in place of boil ing

point

Any ot her

answers

(1)

(Total 14 marks)

Quest ion

Number


Answers

Rej ect Mark

5 (a)

Q / chlorine / Cl2

S / ammonia / NH3

T / hydrogen / H2

Award 1 mark each for any t wo

q

s

t

Cl

H

(2)

Quest ion

Number


Answers

Rej ect Mark

5 (b)

P / carbon dioxide / CO2

R / sulphur dioxide / SO2

p

r

Any ot her

answers

1

1

(2)

(Total 4 marks)


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Mark Schemes Summer 2008 GCSE...2008/08/07 · 1. 4335-1F Mark Scheme 1 2.4335-2H Mark Scheme 11...

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Transcript of Mark Schemes Summer 2008 GCSE...2008/08/07 · 1. 4335-1F Mark Scheme 1 2.4335-2H Mark Scheme 11...