chemistry mark scheme nov 05

7/27/2019 Chemistry Mark Scheme Nov 05

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IGCSE CHEMISTRY 4335, NOVEMBER 2005 MARK SCHEME

Paper 1F

1. (a) nucleus 1

(b) proton 1

(c) electron 1

(d) 2 1

(e) helium 1

Total 5 marks

2. (a) X 1

(b) 20 / 21 1

(c) glowing splintrelights

11

(d) carbon dioxide 1

Total 5 marks

3. (a) zinc + sulphuric acidzinc sulphate + hydrogen 1

(b) effervescenceslowerexothermic

111

(c) burning splint / flamesqueaky pop / explosion

11

(d) (i)(ii)

filtrationbarium chloride (solution)white precipitate

111

Total 9 marks

4. (a) (i)

(ii)(iii)

(iv)

cokelimestoneslag / calcium silicateC(s) + OB2B(g) COB2B(g)formulaestate symbolsCOB2B

1111111


2/11

(b) (i)

(ii)

(iii)

air / oxygenwater / moisturezincprevents air/oxygen/water from contacting ironOR more reactive than iron(covered in) oil

1111

1

Total 11 marks

5. (a) bright/brilliant/blinding flamewhite solid/ ash/ smoke

11

(b) water / HB2BO 1

(c) 11solution/magnesium hydroxide is (weak) alkali / contains hydroxideions

11

(d) (i)(ii)(iii)

hydrochloric (acid)neutralisationwater

111

Total 8 marks

6. (a) hydrogen and carbon only 1

(b) (i)(ii)(iii)

alkanesCBnBHB2n+2BA and D / CHB4Band CB3BHB8

111

(c) (i)

(ii)

compounds with same molecular formulabut different structures/structural formulaenone

111

(d) H HC=C

H H

all atoms and bonds correct

bond angles around C approximately 120

11

(e) 28 1

Total 10 marks

7. (a) nitrogenAirhydrogennatural gas / methane / hydrocarbons(P and Q can be in reverse order)

1111

(b) (i)(ii)

cooled NOT condensedliquid

11


3/11

(c) (unused/recycled) nitrogen and hydrogen 1

Total 7 marks

8. (a) Name ofsubstance

Ionicbonding

Covalentbonding

Insolublein water

Solublein water

ammonia

methane

poly(ethene)

sodium chloride

sodium hydroxide

All six correct 4 marks5 or 4 correct 3 marks3 correct 2 marks2 correct 1 mark 4

(b) (i)(ii)

any suitable use e.g. making bags/food packagingany two from: soap, paper, ceramics, bleach, detergents

12

Total 7 marks

9. (a) potassium manganate(VII) / manganese(IV) oxide 1

(b) UdampUlitmus paperbleached

11

(c) (i)

(ii)

iron(III) chloride

brown solid / precipitate

1

1

(d) (i)(ii)

iodinechlorine is more reactive (than iodine)

11

Total 7 marks

10. (a) a shared UpairUof electrons 1

(b) simpleweak

moleculeslow

11

11

(c) (i)

(ii)

(iii)

hydrogen shown with 1 electronoxygen shown as 2,6one oxygen atom with two hydrogenseach has full outer shell of electronsbent / v-shaped

11111

Total 10 marks


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11. (a) electrons from Mg to FMg loses 2 electronseach of two F gains 1 electron

111

(b) Mgit has lost electrons

11

(c) (i)(ii)

NaP+PFP-PNaF

11

(d) orange / yellow 1

Total 8 marks

12. (a) (i)(ii)

5colourless

11

(b) (i)

(ii)

(iii)

NHB3B+ HCl NHB4BCl OR NHB4BOH + HCl NHB4BCl + HB2BO

reagents (1)products (1); (-1)for incorrect balancing.(heat with) sodium hydroxide solutionammonia /alkaline gas given offtest gas with damp U I / litmus paper turns bluemix together same volumesno indicator/partial evaporation - not to drynesscrystallise solution(ORif use indicator:add charcoalfilterevaporate/crystallise)

2

111111

(c) (i)

(ii)

any soluble lead(II) saltany soluble chlorideany equation that is cq on answer to c(i)

111

Total 13 marks


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Paper 2H

1. (a) Name ofsubstance

Ionicbonding

Covalentbonding

Insolublein water

Solublein water

ammonia

methane poly(ethene)

sodium chloride

sodium hydroxide

All six correct 4 marks5 or 4 correct 3 marks3 correct 2 marks2 correct 1 mark 4

(b) (i)

(ii)

any suitable use e.g. making bags/food packaging

any two from: soap, paper, ceramics, bleach, detergents

1

2

Total 7 marks

2. (a) potassium manganate(VII) / manganese(IV) oxide 1

(b) UdampUlitmus paperbleached

11

(c) (i)(ii)

iron(III) chloridebrown solid / precipitate

11

(d) (i)(ii)

iodinechlorine is more reactive (than iodine)

11

Total 7 marks

3. (a) a shared UpairUof electrons 1

(b) simpleweakmoleculeslow

1111

(c) (i)

(ii)

(iii)

hydrogen shown with 1 electronoxygen shown as 2,6one oxygen atom with two hydrogenseach has full outer shell of electronsbent / v-shaped

11111

Total 10 marks


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4. (a) electrons from Mg to FMg loses 2 electronseach of two F gains 1 electron

111

(b) Mgit has lost electrons

11

(c) (i)(ii)

NaP+PFP-PNaF

11

(d) orange / yellow 1

Total 8 marks

5. (a) (i)(ii)

5colourless

11

(b) (i)

(ii)

(iii)

NHB3B+ HCl NHB4BCl OR NHB4BOH + HCl NHB4BCl + HB2BO

reagents (1)products (1); (-1)for incorrect balancing.(heat with) sodium hydroxide solutionammonia /alkaline gas given offtest gas with damp U I / litmus paper turns bluemix together same volumesno indicator/partial evaporation - not to drynesscrystallise solution(ORif use indicator: add charcoal

filterevaporate/crystallise)

2

111111

(c) (i)

(ii)

any soluble lead(II) saltany soluble chlorideany equation that is cq on answer to c(i)

111

Total 13 marks

6. (a) NaCl(s) If state symbols missing / incorrect,HB2BO(l) (1)for both formulae correct

11

(b) (i)

(ii)

(iii)

silver nitrate (solution)(dilute) nitric acidwhite precipitate

diffusion

111

1

(c) (i)

(ii)

all three pieces drawn in correct sequencecondenser at correct angle and connected via sidearm to rbflask with bung in neck of flask(ALLOWbung + thermometer in top of flask)labels for sea water, cooling water and drinking waterdistillation NOT fractional distillation

11

11

Total 10 marks


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7. (a) Giant structure of (positive/metal/copper) ionselectronsdelocalised / free / mobile

111

(b) (i)

(ii)(iii)

(iv)

(v)(vi)(vii)

greenblack

CuCOB

3B

CuO + COB

2(bubble through) limewaterturns milky/cloudy / white precipitate(dilute) nitric acidneutralisation(pale) blue precipitate(dark) blue[Cu(HB2BO)B2B(NHB3B)B4B]P

2+P

11

11111111

(c) copper(I) oxideCuB2BO

11

Total 15 marks

8. (a) (manufacture of) polymers / poly(ethene) / ethanol(manufacture of) ammonia / margarine / rocket fuel

11

(b)

energy

1

(c) (i)

(ii)

H H H H| |

H C C H C== C| |

H H H H

bonds broken = 348 + (2412) / 1172bonds formed = 612 + 436 / 1048energy change = 124 (kJ/mol)

2

111

(d) increase in temperatureadd catalyst any two for 1 eachincrease pressure

2

(e) (i)

(ii)

() reversible reaction

(H) enthalpy change / energy change / heat changeincreaseddecreased

1111

Total 14 marks

CB2BHB4B(g) + HB2B(g)

CB2BHB6B(g)


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9. (a) fractional distillation 1

(b) gasolinekerosenediesel any two for 1 eachfuel oil

bitumen

2

(c) heat / high temperature / 200 400Cphosphoric acid

11

(d) (i)(ii)

sugar (cane)no crude oilplenty of land/suitable climate to grow sugar cane

111

(e) (i)

(ii)

ethanolsulphuric/phosphoric/hydrochloric acidesters

111

Total 11 marks

10. (a) effervescence / fizzing / bubbleswater goes cloudy / white precipitate any two for 1 eachgets warmerCa + 2HB2BO Ca(OH)B2B + HB2

2

1

(b) zinc oxideZn + HB2BO ZnO + H B2

11

(c) (i)(ii)

Zn + Fe P2+P ZnP2+P + Fe Ignore state symbolsdisplacement / redox

11

(d) oxygen / air 1

(e) (i)(ii)

(coated with) zinczinc more reactive than ironzinc reacts/corrodes instead of iron

111

Total 11 marks

11. (a) 160 1

(b) (i)

(ii)

(iii)

320000 160= 2000

2000 2= 4000

4000 56= 224000 g = 224 (kg)

111111

(c) (i)

(ii)

it reduces the capacity of blood to carry oxygen / correctreference to haemoglobin

5000 24 = 120000 (dm P3P)

1

1

(d) FeB2BOB3B + 3CO 2Fe + 3COB2BAll formulae correct = 1, correct balancing = 1

2


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(e) (i)(ii)

silica / silicon dioxide / sandCaCOB3B CaO + COB2BCaO + SiOB2B CaSiOB3

111

Total 14 marks


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Paper 3

1. (a) Name of apparatus Volume of liquidA measuring cylinder 8.6B beaker 100C pipette 25

D burette 12.3 8

(b) (i)(ii)

BD (burette)

11

Total 10 marks

2. (a) 8006004002000

all 5 = 2 marksany 3 = 1 mark 2

(b) suitable y scaleall points correct (-1 per error)best fit line attempted

121

(c) graph turnsget better idea where maximum is 2

(d) repeat

check consistency of data

1

1

(e) (i)(ii)

(iii)

no oxygen / hydrogen can not react / nothing to react withreference to 2:1 ratio in equationmaximum amount of hydrogen reacting333 (accept 330 or 300) (cm P3P)

12

1

Total 14 marks

3. (a) when acid added 1

(b) (i)

(ii)

(iii)

circled anomalous point (at 5 C)

got warmerabsorbed heat/energy from surroundingsreaction fasterORtoo great a volume of solution(s)bigger depth to look throughharder to see cross / less precipitate needed to obscure cross.7 seconds (from graph)

1

3

1

(c) 1 / b(iii) cq markingcorrect answer (0.143 sP-1P)

2


11/11

(d) faster so percentage error in times greaterloss of heat to surroundings

2

(e) (i)

(ii)

the higher the temp the faster the reactionidea of non linearparticles move faster

more collisions per second / more frequent collisionsmore collisions are successful / have energy > EBAB

2

3

(f) volume thiosulphate constantdifferent volumes aciddifferent volumes water (to keep total volume / depth constant)temp constant 4

Total 19 marks

4. (a) 10.6 (g) 1

(b) decreases 1

(c) fume cupboard / well ventilated roomsulphur dioxide is toxic.

2

(d) evaporation (of water)evaporation Ufaster

11

(e) measure pH 1

Total 7 marks

chemistry mark scheme nov 05

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