0620 CHEMISTRY - Max Papersmaxpapers.com/wp-content/uploads/2012/11/0620_s13_ms_all.pdf · 0620 CHEMISTRY 0620/11 Paper 1 ... NOTE: minimum of 6 (O) ... Page 6 Mark Scheme Syllabus

CAMBRIDGE INTERNATIONAL EXAMINATIONS

International General Certificate of Secondary Education

MARK SCHEME for the May/June 2013 series

0620 CHEMISTRY

0620/11 Paper 1 (Multiple Choice), maximum raw mark 40

Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.

Page 2 Mark Scheme Syllabus Paper

IGCSE – May/June 2013 0620 11

© Cambridge International Examinations 2013

Question Number

Key Question Number

Key

1 B 21 D

2 C 22 C

3 C 23 D

4 D 24 C

5 D 25 D

6 D 26 B

7 C 27 D

8 A 28 D

9 B 29 C

10 D 30 C

11 B 31 B

12 B 32 D

13 C 33 A

14 D 34 B

15 C 35 C

16 B 36 B

17 A 37 C

18 A 38 D

19 C 39 A

20 C 40 A




0620 CHEMISTRY






Question Number

Key Question Number

Key

1 B 21 D

2 A 22 D

3 B 23 B

4 D 24 A

5 A 25 C

6 C 26 B

7 C 27 D

8 C 28 D

9 A 29 A

10 D 30 D

11 B 31 D

12 A 32 A

13 D 33 C

14 A 34 B

15 A 35 D

16 C 36 B

17 C 37 A

18 B 38 B

19 C 39 A

20 C 40 D




0620 CHEMISTRY






Question Number

Key Question Number

Key

1 B 21 C

2 C 22 D

3 D 23 C

4 C 24 D

5 D 25 C

6 C 26 B

7 D 27 D

8 B 28 C

9 A 29 D

10 B 30 C

11 D 31 B

12 C 32 B

13 B 33 D

14 D 34 A

15 B 35 B

16 C 36 C

17 A 37 C

18 A 38 A

19 D 39 D

20 C 40 A




0620 CHEMISTRY

0620/21 Paper 2 (Core Theory), maximum raw mark 80

This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components.




1 (a) (i) E [1] (ii) B [1] (iii) E [1] (iv) A [1] (v) A [1] (vi) D [1] (b) 1 mark for each correct word atom; two; covalent ALLOW: atom; transition; [4] [Total: 10] 2 (a) melting point below (34 °C) and boiling point above (34 °C) [1] ALLOW: its melting point is 29 °C and its boiling point is 669 °C (b) ALLOW: 740–800 °C (actual is 760 °C)` [1] (c) (i) increases (down the group) [1] ALLOW: goes up / goes up except for potassium (ii) sodium / Na [1] (d) 1 mark for each of:

• shiny (when freshly cut) ALLOW: silvery / silver colour

• conducts heat / conducts electricity / conducts

• ductile / can be drawn into wires

• malleable / can be shaped ALLOW: can be bent

• ALLOW: solid at room temperature

• soft (for 1 mark) [3] IGNORE: sonorous / it is a metal




(e) (i) Any two of:

• bubbles

• moves (around)

• floats / on surface

• catches fire / flame

• lilac (flame) ALLOW: mauve or purple

• explodes / spits

• fizzing

• forms a ball

• beaker gets hotter

• gets smaller [2] IGNORE: water goes cloudy / water goes purple or blue (ii) H2 on right; [1] 2 on left (dependent on H2 or 2H on right) [1] [Total: 11] 3 (a) 1 mark for each correct line / indication alkane → C2H6 alkene → C2H4

alcohol → C2H5OH carboxylic acid → CH3COOH [4] (b) Full structural formula shown i.e.

H H | | H – C – C – H | | H H [1]

ALLOW: correct dot and cross diagram (c) saturated has only single bonds / no double bonds; [1] unsaturated has double bond(s) [1] IGNORE: one has single bonds and the other has double bonds




(d) bromine water / aqueous bromine / bromine / ALLOW: correct formula; [1] IGNORE: Br (saturated hydrocarbon) no reaction / stays the same colour / remains orange / remains

orange-brown [1] ALLOW: remains brown ALLOW: remains yellow (if aqueous bromine used) / remains red (if bromine used) IGNORE: remains yellow (if bromine used) REJECT: incorrect colour, e.g. stays same blue colour, does not score (unsaturated hydrocarbon) decolourises / goes colourless [1] IGNORE: goes clear IGNORE: initial incorrect colour of bromine (acidified) potassium permanganate / potassium manganate(VII) (1 mark) goes colourless / purple to colourless (1 mark) IF: incorrect reagent 0 for this question [Total: 10] 4 (a) two marks for names of elements present: [2]

nitrogen + phosphorus + potassium (or correct symbols) = 2 marks

NOT: N2 any two of nitrogen, phosphorus or potassium (or symbols) = 1 mark two marks for reasons: [2] any two of:

• soil depleted of minerals / depleted of essential elements / depleted of any of N or P or K

ALLOW: plants use up minerals / use up essential elements / use up N or P or K

• to increase the nitrogen or phosphorus or potassium in the soil ALLOW: to increase the nitrates in the soil / to increase the phosphates in the soil

• increased growth / more growth / better growth (idea of more growth needed) ALLOW: more rapid growth / quicker growth ALLOW: produce more crops IGNORE: produce more unqualified IGNORE: for growth / to grow / to keep plants healthy / for healthier growth

• (for making) more protein NOTE: to increase the nitrogen (or N) in the soil = 1

(0 mark for elements and 1 for increase of that element) to increase the N + P in the soil = 2 (1 mark for two of the elements and one for idea of increase)

(b) (i) CON2H4 [1] ALLOW: any order (ii) 60 [2] if 2 marks not scored: ALLOW 1 mark for correct atomic masses N = 14, O = 16, H = 1, C = 12 anywhere in working NOTE: no e.c.f.




(c) regular arrangement; [1] NOTE: minimum of 2 rows of 3 molecules required molecules touching each other [1] NOTE: minimum of 6 (O) are required all of which are touching or very close together. REJECT: molecules in a single row touching (d) (damp red) litmus (paper); [1] ALLOW: pH paper turns blue [1] NOTE: second mark dependent on first being correct ALLOW: universal indicator / full range indicator (paper) (1 mark) turns purple / blue (1 mark) ALLOW: hydrochloric acid (1) gives white fumes (1) [Total: 11] 5 (a) (i) D [1] (ii) C [1] (iii) A [1] (b) (i) loss of carbon dioxide / loss of gas [1] (ii) accept values from 360–380 [1] ALLOW: 6 min to 6 min 20 s / 6 ⅓ min (iii) 0.5 (g) [1] (iv) (initial) gradient greater / slope greater and starts at 0, 0; [1] same final volume [1] (v) (rate) increases [1] IGNORE: more carbon dioxide per second ALLOW : (rate) faster [Total: 9] 6 (a) (i) Any three of: [3]

• add propanol to the mixture and shake (or stir)

• implication of filtration of solution / diagram of filter funnel and filter paper REJECT: diagram of filter paper circle on top of funnel

• sugar solution goes through the filter paper / sugar solution is the filtrate / diagram shows sugar solution (labelled) passing through filter paper

• salt or sodium chloride remains on filter paper / diagram shows salt or sodium chloride (labelled) remaining on filter paper




(ii) evaporate the water / evaporation [1] IGNORE: heat ALLOW: distillation (b) (i) NaCl [1]

ALLOW: Na+Cl

– REJECT: Na+ + Cl

– / multiples, e.g. 2NaCl

(ii) ionic [1] (c) (i) D [1] (ii) positive electrode → chlorine / Cl2 [1]

IGNORE: Cl

negative electrode → hyrdrogen / H2 [1] IGNORE: H IF: correct electrode products reversed = 1 mark [Total: 9] 7 (a) Any four of:

• evaporates or evaporation (of hydrogen chloride)

• movement of particles

• hydrogen chloride particles (move) / HCl

particles (move) ALLOW: hydrochloric acid particles (move)

• diffusion

• particles collide (with each other)

• spreading out of particles

• random (movement of particles)

• HCl particles hit litmus

• ALLOW: (HCl ) particles (move from higher) to lower concentration

ALLOW: molecules or atoms in place of particles

NOTE: no mark for acid turning damp blue litmus red NOTE: hydrogen chloride particles move = 2 mark NOTE: random movement of hydrogen chloride particles = 3 marks [4]

(b) ammonium chloride [1] REJECT: ammonia chloride




(c) (i) iron + hydrochloric acid → iron(II) chloride + hydrogen [1] IGNORE: symbol equation REJECT: iron chloride (ii) add sodium hydroxide (solution / aqueous) ammonia; [1] ALLOW: add ammonium hydroxide greyish-green precipitate [1] ALLOW: green ppt. IGNORE: what happens in excess reagent NOTE: second mark dependent on first being correct (d) (i) control / standard / idea of making fair comparison [1] (ii) water / H2O [1] air / oxygen / O2 [1] IGNORE: O APPLY: listing for other incorrect substances (iii) air not present / oxygen not present / water not present [1] (iv) air and water can get to the surface of the iron / oxygen and water can get to the iron [1] IGNORE: ideas that not all surface is protected [Total: 13] 8 (a) (i) better conductor ORA [1] IGNORE: it conducts / good conductor IGNORE: it is softer / easier to draw into wire (ii) too expensive / higher cost [1] IGNORE: it has a low melting point (iii) higher melting point; [1] IGNORE: high melting point cheaper [1] (iv) (plastic) is an insulator; [1] explanation of insulator, e.g. does not conduct electricity [1] ALLOW: so you don’t get an electric shock (b) B [1] [Total: 7]




0620 CHEMISTRY






1 (a) (i) D / chlorine / Cl2 [1] E / carbon / graphite [1] IGNORE: C REJECT: diamond (ii) E / carbon / graphite [1] IGNORE: C REJECT: diamond (iii) C / ammonia / NH3 [1] (iv) A / ethanol [1] IGNORE: alcohol (v) E / graphite / carbon [1] IGNORE: C REJECT: diamond (b) atom; combined; molecules; ionic (1 mark each) [4] [Total: 10] 2 (a) increases [1] (b) 5.2–6.6 (actual = 5.96) [1] (c) (substance which) speeds up chemical reaction / increases reaction rate / lowers activation

energy [1] (d) Any three of: [3]

• high boiling point / high melting points • high density / they are very dense IGNORE: they are dense • form coloured compounds REJECT: they are coloured • have different oxidation states / form ions with different charges • form complex ions • ALLOW: they are hard(er)/ strong

(e) 3 (Fe) [1] 4 (H2O) [1]




(f) iron sulfate [1] IGNORE: incorrect oxidation number of iron IGNORE: formula hydrogen [1] IGNORE: formula [Total: 10] 3 (a) A = (volumetric) pipette [1] B = burette [1] C = (conical) flask ALLOW: Erlenmeyer (flask) [1] D = (filter) funnel [1] (b) (i) 13.2 [1] (ii) 10 (cm3) [1] (iii) (pH) 7 [1] (c) (i) 2nd and 3rd boxes ticked (calcium carbonate and calcium oxide) [2] (one mark each) APPLY: listing

(ii) so that crops grow well / so crops grow better / allows maximum growth/ plants don’t grow as well in too acidic conditions/plants killed/plants die [1]

IGNORE: plants can grow [Total: 10] 4 (a) (i) correct structure of methane showing all atoms and bonds [1] (ii) name of any alkane other than methane [1] IGNORE: formulae (iii) Any one of: [1] (waste product from digestion in) cows / other suitable animals/ marshes / paddy fields / bacterial decay / decomposition of vegetation IGNORE: industrial sources / leaking from the Earth (iv) CO2 on right [1] 2 on left [1] NOTE: second mark dependent on the first being correct




(b) (i) (differences in) boiling point(s) [1] (ii) 1 mark each [4] diesel → fuel for cars / lorries fuel oil → fuel for ships kerosene → fuel for jet aircraft naphtha → making chemicals [Total: 10] 5 (a) oxygen + 20/21 (%) [1] nitrogen + 78/79 (%) [1] sulfur dioxide + correct source e.g. burning fossil fuels or named fossil fuel [1] carbon monoxide + correct source e.g. car exhausts / car engines / incomplete combustion

(of fossil fuels) [1] oxides of nitrogen + correct source e.g. car exhausts / car engines / lightning [1] (b) (i) PbS [1] (ii) oxygen removed (from lead oxide) / carbon takes away the oxygen [1] IGNORE: reference to electrons (c) (i) arrangement: irregular / (fairly) random / not ordered [1] closeness: (very) close / touching / near [1] (ii) C2H4Cl2 (ALLOW: any order) [1] (iii) 99 [2] (If 2 marks not scored ALLOW correct atomic masses seen C = 12, H = 1,

Cl = 35.5 anywhere in the question for 1 mark) [Total: 12]




6 (a) zinc → magnesium → calcium → rubidium [2] 1 mark for 1 pair reversed ALLOW: all reversed for 1 mark (b) zinc/ iron [1] REJECT: if K / Na / Al included = 0 marks (c) (i) 2 electrons in outer shell [1] 8 electrons in middle shell [1] ALLOW: 2,8,2 in numbers for 2 marks (ii) 14 [1] [Total: 6] 7 (a) ions can move / ions are mobile [1] IGNORE: it has an ionic structure REJECT: if mention of atoms/ molecules (b) it is a molecular structure / it has no ions [1] IGNORE: electrons can’t move (c) add water and shake / stir / mix [1] filter [1] (d) (i) C [1] (ii) graphite [1] (iii) negative electrode: zinc / Zn [1] positive electrode: chlorine / Cl2 [1]

IGNORE: Cl REJECT: Chloride / Cl

-

(iv) acidify / add nitric acid [1] REJECT: add sulfuric acid / add hydrochloric acid add (aqueous) silver nitrate [1] white precipitate [1] 3rd marking point dependent on correct reagent (silver nitrate) [Total: 11]




8 (a) Any four of: [4]

• sugar dissolves • sugar particles become separated or water molecules get in between sugar particles • diffusion • movement of particles (in solution) • random (movement) • (sugar) particles constantly collide with (water) molecules • particles (in solution) spread out / seperate • ALLOW: particles move from concentrated to dilute (sugar) solution

(b) (i) 3 [1] (ii) 12 [1] (iii) any OH group ringed / all OH groups ringed [1] (iv) carbon dioxide [1] IGNORE: CO2 (v) yeast [1] no air / oxygen present [1]

IGNORE: reference to temperatures between 5–45 oC (vi) solvent / fuel / making a named chemical e.g. making ethanoic acid and esters /

antiseptic / medical wipes / cleaning fluid / vodka sauce / paints/ disinfectant / preservatives [1] IGNORE: unqualified uses e.g. in cars / food / cooking

[Total: 11]




0620 CHEMISTRY






1 (a) (i) A; E (1 mark each) [2] (ii) C [1] (iii) C [1] (iv) B [1] (b) He

3

2 [1]

ALLOW: D3

2

(c) 1 mark each for: [4] protons; neutrons; radioactive; energy; ALLOW: neutrons [Total: 10] 2 (a) (i) boiling point below room temperature [1] ALLOW: it boils at –35 °C IGNORE: boiling point is too low (ii) melting point below room temperature and boiling point above room temperature [1] ALLOW: it melts at –7 °C and boils at 59 °C IGNORE: other stated figures (b) increases (down the group) [1] (c) ALLOW: 0.06 – 0.08 (actual = 0.071) [1] (d) green / light green / yellow-green [1] REJECT: yellow alone REJECT: blue-green (e) 7 electrons in outer shell; [1] 8 electrons in middle shell [1] NOTE: electrons can be shown as dots, crosses or e– ALLOW: 2, 8, 7 in numbers for 2 marks




(f) (i) Br2 on right; [1] 2 on left (dependent on Br2 or 2Br on right) [1] (ii) iodine is less reactive than bromine ORA [1] NOTE: both iodine and bromine (or symbols or formulae) are required ALLOW: bromine is higher in the electrochemical series than iodine IGNORE: less reactive than bromide IGNORE: iodine is lower in the group / Periodic Table than bromine ORA [Total: 10] 3 (a) Any four of: [4]

• in solid, particles are arranged regularly (or are ordered) / in a lattice • in solid, particles are close together • in solid, particles are not moving / only vibrate / are in fixed position • in liquid, particles randomly arranged / disordered / have random motion • in liquid, particles slide over each other / move slowly • in liquid, particles are close together

IGNORE: particles are closer together Any one of: [1]

• during melting, particles become less ordered • during melting, particles start moving / move more / move faster

IGNORE: during melting, particles get further apart NOTE: there must be a reference to particles to score marks (b) Any three of: [3]

• lustrous or shiny ALLOW: silvery

• conduct heat / conduct electricity / conduct • malleable or can be shaped: ALLOW: can be bent • ductile / can be drawn into wires

• ALLOW: solid at room temperature / solid below 37 °C

IGNORE: high boiling point / comments about density / sonorous / comments about hardness

(c) Ga2Cl 6 [1] (d) (i) lower density / better electrical conductor [1] IGNORE: low density / lighter / lightweight / good electrical conductor NOTE: comparative needed (ii) stronger / cheaper [1] NOTE: comparative needed (iii) lower density; cheaper (1 mark each) [2] NOTE: comparative needed




(e) food containers / cooking utensils / aircraft or cars (bodywork) / rail truck (or rail car) (bodywork) / bicycles / (drink) cans / foil / windows / doors / roofing / walking poles / alloy magnets / (some types of) CD’s / transistors / (high brightness) LEDs / paints / (solid) rocket fuels / coins / guitar plates (or necks) / mirrors / any other suitable use [1]

[Total: 14] 4 (a) (i) filtration: idea of removing larger particles or insoluble particles; [1] ALLOW: to remove clay particles / soil particles / sticks / large impurities IGNORE: remove large molecules / to remove impurities / to clean the water chlorination: to kill bacteria [1] ALLOW: to kill germs / to kill microorganisms IGNORE: to disinfect / to remove bacteria / to get bacteria out (ii) any suitable use for water in the home, e.g. for washing / cooking / cleaning / sanitation [1]

IGNORE: for cooling but ALLOW: for cooling body, i.e. lowering body temperature (of fever)

IGNORE: industrial uses (b) anhydrous / white copper sulfate; [1] IGNORE: incorrect oxidation numbers turns blue [1] OR anhydrous / blue cobalt chloride (1 mark); turns pink (1 mark) NOTE: second mark dependent on first being correct BUT: copper sulfate turns blue / cobalt chloride turns pink = 1 mark (c) (i) dot and cross placed between each H atom and the O [1] ALLOW: two dots / two crosses / two ‘e’ for each bond IGNORE: electrons in inner shell of oxygen if drawn REJECT: inner electron shells given to hydrogen / extra electrons in outer shell of

hydrogen or oxygen (ii) covalent + reasons, e.g. because electrons are shared / pair of electrons form the bond(s) [1] IGNORE: because they are two non-metals (d) (pH) 7 [1] (e) sodium + water → sodium hyrdroxide + hydrogen [1] IGNORE: symbol equations [Total: 9]




5 (a) exothermic [1] IGNORE: combustion (b) O2; [1] 2 (dependent on O2 or 2O) [1] (c) (i) B [1] (ii) fuel for cars / fuel for vehicles [1] ALLOW: implication of powering cars / vehicles IGNORE: fuel or cars without any qualification (d) (i) all points plotted correctly; [2] IF: 1 point incorrectly plotted = 1 mark line correctly drawn through points [1] (ii) 99 (°C) or from value correctly shown on graph with incorrect line [1] (e) (i) Any two of: [2] (group of chemicals with)

• similar chemical properties IGNORE: same chemical properties

• same functional group

• same general formula IGNORE: have a general formula

• successive members differ by CH2 group

• general trend in physical properties

(ii) high temperature / heat; [1] ALLOW: stated temperatures between 300 and 900 °C IGNORE: temperature unqualified catalyst; [1] ALLOW: aluminium + silicon oxides / zeolites REJECT: incorrect name alone, e.g. nickel OR high pressure (1 mark) ALLOW: stated pressures between 50–100 atmospheres IGNORE: pressure unqualified

[Total: 13]




6 (a) Any four of: [4]

liquid in beaker / other suitable container with chromatography paper dipping into the liquid solvent labelled or named as word solvent or as specific named solvent (must be in correct context, e.g. in beaker) REJECT: solution of substance to be chromatographed spot placed on paper above solvent level allow solvent to run up the paper / solvent carries the dyes up the paper the spots separate / different dyes go different distances IGNORE: the dyes separate (in stem of question) compare distance spot moves to a standard ALLOW: more advanced points, e.g. mark solvent front / compare Rf values ALLOW: marks from labelled diagram

(b) (i) F [1] (ii) G [1] (iii) G [1] (c) C – O – H [1] ║ O ALLOW: COOH / CO2H (d) substance which dissolves another / substance which dissolves a solute [1] (e) (i) 4 [1] (ii) 10 [1] [Total: 11]

7 (a) (i) protein / catalyst; [1] speeds up a reaction / increases rate of reaction / makes reaction faster [1] ALLOW: changes the rate of a reaction IGNORE: makes a reaction slower (ii) 2 (on left) and no other figures added; [1] (b) (i) increasing the concentration increases rate ORA [1] IGNORE: concentration increases rate (ii) initial slope of line between that of 0.2 and 0.4 mol dm–3 concentrations; [1] line levels off about half way between 18 and 22 cm3 [1]




(iii) volume – 26 (cm3) [1] time – 20 (s) [1] (c) (i) loss of oxygen / decrease in oxidation number / gain of electrons [1] ALLOW: gain of hydrogen (ii) calcium sulfate; [1] water [1] IGNORE: symbol equation APPLY: listing (iii) add (aqueous) silver nitrate; [1] (pale) yellow precipitate [1] (second mark dependent on first being correct) OR add (aqueous) lead nitrate (1 mark) yellow precipitate (1 mark) (second mark dependent on first being correct) [Total: 13]




0620 CHEMISTRY

0620/31 Paper 3 (Extended Theory), maximum raw mark 80





1 (a) (i) contains carbon and hydrogen [1] cond: only / just [1]

(ii) (different) boiling points [1]

cond: separate [1] (b) bitumen-making roads / roofs / water-proofing, etc. [1]

lubricating fraction – waxes / vaseline / grease, etc. or machinery example, e.g. (oil a) bike / hinges / reducing friction [1]

paraffin fraction – jet fuel / (home) heating or tractors or cooking or lighting [1]

gasoline fraction – petrol or fuel for cars / vans / trucks [1] [Total: 8]

2 (a) 3 or III [1]

(b) good conductor and it is a metal/has delocalised (free) electrons [1]

(c) N or P or As or Sb [1] accept Bi

(d) M2(SO4)3 [1] accept: Ga2(SO4)3

(e) it would react with/dissolves in a named strong acid [1] it would react with/dissolves in a named alkali [1] it shows both basic and acid properties =1 [1] it reacts with both acids and bases/alkalis =1 [1] [max 2]

[Total: 6]




3 (a) (i) pieces have (same) surface area [1] same amount / mass / quantity / volume / number of moles of carbonate [1]

(ii) no more bubbles / carbon dioxide or piece disappears / dissolves [1]

(b) experiment 1 Ca2+ + CO2 + H2O [1]

(c) (i) more concentrated or higher concentration (of acid) (in experiment 1) [1] accept: arguments based on collision theory

(ii) ethanoic acid is a weak acid or hydrochloric acid is a strong acid [1] accept: stronger or weaker

ethanoic acid less ionised / dissociated / lower / smaller concentration of hydrogen ions [1] accept: less hydrogen ions and vice versa argument but not dissociation of ions

(iii) lower temperature (particles) have less energy [1]

moving more slowly [1] fewer collisions / lower collision rate [1] or lower temperature (particles) have less energy [1] fewer particles collide [1] with the necessary energy to react [1] note: less energy fewer successful collisions gains all 3 marks

[Total: 10] 4 (a) it is an alkane or hydrocarbon [1]

it is saturated or only C—C single bonds [1] accept: no double bonds

(b) molecular formula C6H12 [1] empirical formula CH2 [1]

(c) correct structural formula of cyclobutane [1]




(d) (i) C6H12 [1] accept: a correct structural formula

(ii) same molecular formula not: chemical formula [1]

different structural formulae / structures [1]

(e) add bromine (water) or (l) [1] cond: (remains) brown or orange or red or yellow [1] cond: changes from brown, etc. to colourless or decolourises [1] not: clear OR potassium manganate(VII) [1] note: oxidation state not essential but if given must be correct or [0] accept: potassium permanganate cond: remains pink / purple [1] cond: changes from pink to colourless (acidic) [1] not: clear cond: change from pink to green / brown (alkaline)

[Total: 11] 5 (a) (i) any metal above zinc

Mg → Mg2+ + 2e– [1]

(ii) Zn + 2Ag+ → Zn2+ + 2Ag [2] Note: not balanced only [1]

(iii) because they can accept or gain electrons / change into atoms or can be reduced [1]

(iv) Ag+ or silver [1]

charge not essential but if given must be correct

(v) Ag+ and Cu2+ or silver and copper [1] charge not essential but if given must be correct




(b) Cu Sn Cd Zn (i.e. all 4 in correct order) [1] relates order to voltage [1]

one relevant comment from: [1] higher reactivity metals are the negative electrode / copper is least reactive because it is the positive electrode because copper would have the lowest voltage / copper cell V = 0 / the bigger the difference in reactivity, the bigger the voltage / zinc has highest voltage because it is most reactive / more reactive metals have higher voltage

[Total: 9] 6 (a) (i) proton or H+ acceptor [1] (ii) (measure) pH or (use) UI indicator [1]

note: can be implied need not be explicit sodium hydroxide has higher pH / ammonia(aq) has lower pH [1] (this sentence would score 2 marks) or appropriate colours with UI / appropriate numerical values [1] ammonia is closer to green, blue-green, turquoise or lighter blue sodium hydroxide is darker blue / purple / violet [1] or measure electrical conductivity [1] can be implied need not be explicit ammonia (aq) is the poorer conductor/ sodium hydroxide is the better conductor [1]




(b) any five from:

• high pressure favours lower volume side / movement to right / ammonia side, or high pressure increases the yield

• high pressure increases rate

• low temperature favours exothermic reaction / increases yield / favours the forward reaction

• low temperature gives low rate or vice versa

• catalyst increases rate or lowers activation energy

• 450 °C low enough to give an economic yield but with catalyst gives a fast enough rate note need whole concept to get this compromise temperature point [5]

(c) 2NH3 + NaClO → N2H4 + NaCl + H2O [2] not balanced only 1

(d) 4 hydrogen atoms 1 bonding pair each [1] 2 nitrogen atoms with 1 bonding pair between them [1] one non-bonding pair on each N (need not be seen as a pair) [1]

(e) (i) pH increases [1]

(ii) oxygen needed for rusting / removes oxygen / reacts with oxygen [1] [Total: 15] 7 (a) (i) add carbon / animal charcoal [1]

filter [1]

OR repeat experiment without indicator [1] using same quantity / volume of acid [1]

(ii) add magnesium metal / carbonate / oxide / hydroxide

to (hot) (hydrochloric) acid [1]

cond: until in excess or no more dissolves or reacts [1]

cond: filter (to remove unreacted solid) [1]




(b) number of moles of HCl = 0.020 x 2.20 = 0.044 [1] number of moles of LiOH = 0.044 concentration of LiOH = 0.044/0.025 = 1.769 (mol / dm3) [1] accept 1.75 to 1.77 need 2 dp correct answer scores = 2

(c) (for LiCl.2H2O) mass of one mole = 78.5 [1] percentage water = 36 / 78.5 x 100 [1] 45.9 so is LiCl.2H2O [1] only award the marks if you can follow the reasoning and it gives 45.9% of water note: if correct option given mark this and ignore the rest of the response allow: max 2 for applying a correct method to another hydrate, [1] for the method and [1] for the correct value, working essential

[Total: 10] 8 (a) (i) regular arrangement / repeating pattern NOT structure [1]

cond: ions [1] not molecules / atoms

(ii) attraction between opposite charges / electrostatic attraction [1]

(b) delocalised / mobile / free / sea of electrons [1] positive ions / cations not atoms / protons / nuclei [1] attraction between these electrons and ions [1]

(c) giant covalent

no ions [1] no delocalised / free / mobile / sea of electrons or all electrons [1]

ionic in ionic solid ions cannot move [1] liquid ionic compound ions can move [1]

metallic (both solid and liquid) metals have delocalised (or alternative term) electrons [1] [Total: 11]




0620 CHEMISTRY






1 (a) (i) named noble gas [1] accept: any noble gas accept: symbol

(ii) H2O / CO2 [1]

not: names not: equations

(b) (i) oxygen and nitrogen (in air) (react) [1] at high temperature [1] accept: in engines / lightning not: in exhausts

(ii) fossil fuels / fuels which contain sulfur [1]

accept: named fossil fuel such as coal / oil / natural gas burn / combust [1]

(iii) any two from:

damage buildings / soil acidification / leaching from soil / soil nutrients become unavailable / kill microbes / acidify lakes / kill fish / damage trees / reduction in plant growth / crop loss [2]

(c) (i) oxygen reacts with copper [1] to form copper oxide (which is black) [1]

(ii) measure volume at room temperature / gas has different volumes at different

temperatures / volume of gas depends on temperature / hot gas has higher volume / heat causes expansion (of gases) / ORA [1]

(iii) no oxygen left or all the oxygen has reacted (with copper) [1] (iv) 39–40 cm3 note: units required [1]

2 (a) B 3919

K [1]

positive charge + [1]

C 6530

Zn [1]

D 168O [1]

charge 2– [1]

E 7031

Ga [1]

(b) number of p = number of e [1]

number of p > number of e [1]

number of p < number of e [1]




3 (a) (i) complete combustion / combustion in excess oxygen [1]

of fuels containing carbon / fossil fuels / hydrocarbon (fuels) [1]

produce carbon dioxide / increase percentage of CO2 in atmosphere [1]

(ii) living things / cells / plants / animals / humans / micro-organisms [1] (oxidise / react with) oxygen and food / foodstuff / named foodstuff / carbohydrate / sugar / glucose [1] produces carbon dioxide [1]

(b) (i) glucose or starch or carbohydrate [1] oxygen [1]

(ii) light / sunlight / sun / UV [1]

chlorophyll accept: chloroplast [1]

4 (a) (i) first reaction

volume / moles / molecules of reactants and products are different [1]

second reaction volume / moles / molecules of reactants and products are the same [1]

(ii) first reaction (forward) reaction is endothermic [1]

second reaction (forward) reaction is exothermic [1]

(b) (i) C8H18 → 2C4H8 + H2 [1]

(ii) 2H+ + 2e → H2 [2] or 2H3O

+ + 2e → H2 + 2H2O accept: –2e on right hand side accept: e– note: not balanced = 1

(iii) chlorine / Cl2 / [1]

cond: water treatment / solvents / plastics / PVC / bleach / disinfectants / HCl / kill bacteria / sterilising water / chlorination of water / swimming pools / pesticides / herbicides / insecticides / germicides / pharmaceuticals [1]

sodium hydroxide/NaOH [1] cond: making soap / degreasing / making paper / detergents / bio-diesel / paint stripper / clearing drains / alumina from bauxite / oven cleaner / bleach [1]




5 (a) (i) does not decay or non-biodegradable or flexible or bendable or easily moulded or low density / light / lightweight or waterproof / insoluble in water or does not corrode or durable [1]

(ii) any two from: [2]

chlorine hydrogen chloride carbon monoxide

(b) (i) CH3—CH = CH2 [1] note: can be fully or semi-displayed, C = C must be shown

(ii) correct repeat unit [1]

–CH(C6H5)–CH2–

continuation shown [1]

(c) glucose two products (polymer and water) / condensation (polymerisation) / (small) molecules removed [1]

phenylethene one product (polymer) / addition (polymerisation) [1]

6 (a) (i) ions cannot move / no free ions in solid state [1]

ions can move / free ions in liquid state [1] note: ions can only move in liquid state = 2

(ii) reduce melting point / reduce energy costs / better conductor when dissolved in cryolite [1]

(iii) burns in oxygen / reacts with oxygen / oxidised by oxygen / forms carbon dioxide / forms

carbon monoxide [1]

(iv) high melting point / inert / unreactive [1]

(b) protective / unreactive / resists / prevents corrosion / non-porous (layer) [1]

of (aluminium) oxide [1]

(c) (i) good conductor (of electricity) [1] low density / light / lightweight [1]

(ii) steel core (increased) strength / prevent sagging / to increase separation of pylons / support [1]




7 (a) (i) CH3COOCH2CH3 / CH3CO2CH2CH3 / CH3COOC2H5 / CH3CO2C2H5 / C2H5OOCCH3 / CH3CH2OOCCH3 not: –OCO– linkage [1] note: formulae can be displayed or semi-displayed note: penalise sticks (i.e. any missing atoms)

(ii) butyl methanoate [1]

(b) (i) fats / vegetable oils / triglycerides / lipids [1]

(ii) two correct ester linkages, e.g. –OOC / –O2C and –COO / –CO2 [1]

contents of the ‘boxes’ being C6H4 and C2H4 or CH2CH2 [1] continuation bonds at both ends [1]

(c) (i) to make colourless / invisible (spots) [1]

visible / coloured / seen / position made clear / indicate [1]

(ii) distance travelled by sample = Rf [1] distance travelled by solvent (front)

(iii) sample 1 Rf = 0.20 to 0.24 tartaric (acid) [1]

sample 2 Rf = 0.44 to 0.48 malic (acid) [1] 8 (a) (i) (the number of particles which is equal to the number of atoms in) 12 g of carbon 12

or the mass in grams which contains the Avogadro’s constant number of particles or

Avogadro’s constant or 6 to 6.023 × 1023 of atoms / ions / molecules / electrons / particles or (the amount of substance which has a mass equal to) its relative formula mass / relative atomic mass / relative molecular mass in grams or (the amount of substance which has a volume equal to) 24 dm3 of a gas at RTP [1]

(ii) (Avogadro’s constant is the) number of particles / atoms / ions / molecules in one mole of a substance or the number of carbon atoms in 12 g of C(12). or the number of particles / molecules in 24 dm3of a gas at RTP or

6 to 6.023 × 1023 (particles / atoms / ions / molecules / electrons) [1]

(b) CH4 and SO2 [1]

2/16 = 1/8 or 0.125 moles of CH4 AND 8/64 = 1/8 or 0.125 moles of SO2 [1]




(c) (i) 4.8/40 = 0.12 moles of Ca 3.6/18 = 0.2 moles of H2O both correct [1]

(ii) Ca is in excess (no mark) (because 0.12 moles of Ca need) 0.24 moles / 4.32 g of H2O

to react [1] there is not enough / there are 0.2 moles / 3.6 g of H2O [1] or Ca is in excess (no mark) (because 0.2 moles / 3.6 g of water will react with) 0.1moles/4.0 g of Ca [1] there is more than that / there are 0.12 moles / 4.8 g of Ca [1] or Ca is in excess (no mark) because the mole ratio Ca:H2O is 3:5 / mass ratio 4:3 [1] which is bigger than the required mole ratio of 1:2 / mass ratio 10:9 [1] or Ca is in excess (no mark) because the mole ratio H2O:Ca is 5:3 / mass ratio 3:4 [1] which is smaller than the required mole ratio of 2:1 / mass ratio 9:10 [1]

(iii) 0.02 × 40 = 0.8 (g) [1]




0620 CHEMISTRY






1 (a) (i) element cannot be broken into anything simpler [1] by chemical means [1] OR made up of one type of atom only [2]

(ii) compound two or more different elements [1] chemically bonded together [1] (iii) mixture

two or more substances not chemically joined together [1]

(b) (i) mixture [1] (ii) compound [1] (iii) element [1] (c) conductivity (of heat or electricity) [1] [Total: 9] 2 (a) (i) large / high surface area [1] high collision rate / collide more / many collisions [1] (between oxygen molecules and aluminium atoms) NOT faster collisions

(ii) concentration [1] of reactants decreases [1] allow one mark ONLY for: for reactants used up or amount of reactant decreases (iii) any three of four from one strand:

M1 increase in temperature

M2 molecules move faster or particles have more energy

M3 higher collision rate

M4 more successful collisions or more particles have enough energy to react/Ea

[3] (b) (i) flour or wood dust or coal dust or carbon or sugar [1]




(ii) any three from: powder and larger pieces / different sized particles use suitable named solid, e.g. magnesium suitable named solution, e.g. named acid or copper sulfate(aq) result – powder reacts faster than larger pieces [3] NOT Cu (with acid); K / Na with anything 3 (a) (i) cars, ships, bridges, construction, white goods, screws, nails, roofing, fencing, etc. [1]

(ii) e.g. stainless steel [1] cooking utensils, surgical equipment, sinks or main use [1] (b) blow in oxygen NOT air [1] carbon dioxide and sulfur dioxide (escape as gases) [1] COND on reaction with air / oxygen add calcium oxide / quicklime [1] ALLOW calcium carbonate, limestone phosphorus oxide or silicon oxide (are acidic) reacts (with calcium oxide / CaCO3) [1] to form slag / calcium silicate [1] 4 (a) (i) any ambiguous formula, e.g. GeH3-GeH2-GeH3 [1] (ii) GenH2n+2 [1] NOT C instead of Ge (b) correct formula COND 4bps around germanium atom [1] COND 3nbps and 1bp around each chlorine atom [1] (c) four oxygen atoms around each germanium atom [1] two germanium atoms around each oxygen atom [1] tetrahedral [1] (d) oxidation [1] COND increase in oxidation number [1] ACCEPT: electron loss




5 (a) (i) any Group 1 metal [1] ACCEPT: lithium

(ii) 2Pb(NO3)2 → 2PbO + 4NO2 + O2 [2] PbO [1] COND balancing [1] (iii) the metal in a (i) is more reactive than lead [1] more reactive metals have more stable compounds OR has stronger (ionic) bonding [1] (b) (i) speed / rate of forward reaction = speed / rate of back reaction [1] OR macroscopic properties do not change / constant (with time) (ii) goes darker OR goes brown [1] COND lower pressure favours side with more moles [1] COND this is NO2 side OR reactant side OR goes left [1] (iii) exothermic [1]

low temperatures favour the exothermic reaction or low temperatures moves equilibrium to right / product side / towards N2O4 [1]

(iv) forward reaction is bond forming [1] 6 (a) (i) measure melting point NOT just heating [1]

pure sample would melt at 135 °C [1]

OR impure would melt lower than 135 °C (ii) C3H4O4 [1] (iii) C2H4O2 OR CH3COOH [1] ethanoic OR acetic acid [1] both marks are independent of each other (iv) ester NOT organic, covalent [1] (b) (i) malonic is a weaker acid/less dissociated OR sulfuric acid is a stronger acid/more dissociated [1] NOT sulfuric acid is a strong acid




(ii) add piece of suitable metal, e.g. Mg ALLOW Al, Ca NOT K, Na, Cu [1] sulfuric acid reacts faster OR malonic reacts slower [1] OR as above add a piece of CaCO3, if soluble carbonate then [1] only OR measure electrical conductivity [1] sulfuric acid is the better conductor OR malonic acid poorer conductor [1] NOT sulfuric acid is a good conductor (c) (i) sodium malonate and water [1] (ii) CuSO4

H2O [2] (iii) CH2(COO)2 Mg

H2 [2] (iv) K2SO4 CO2 and H2O NOT H2CO3 [2] [Total: 16] 7 (a) (i) a compound which contains carbon and hydrogen only [1] (ii) alkanes contain only C-C single bonds or they are saturated (hydrocarbons) or have the general formula CnH2n+2 [1] alkenes contain at least one C=C double bond or they are unsaturated (hydrocarbons) or have the general formula CnH2n [1]

(b) C20H42 → 2C4H8 + 2C2H4 + C8H18 [1] (c) (i) any unambiguous structure of BrCH2CH2Br [1] NOT just C2H4Br2

(ii) CH3-CH=CH-CH3 [2] For any butene [1] only

(iii) (CH3-CH2-CH=CH2) + H2O [1] → CH3-CH2-CH2-CH2OH [1] [2] ALLOW CH3-CHOH-CH2-CH3 butene reacts with water/steam (to form butanol) ONLY [1]

(iv) C6H12 + H2 → C6H14 [2] alkenes react with hydrogen [1] ONLY (d) volume of oxygen used = 150 cm3 [1]




volume of carbon dioxide formed = 100 cm3 [1] any equation of the combustion of an alkene e.g. 2C5H10 + 15O2 � 10CO2 + 10H2O formulae [1] COND balancing [1]




0620 CHEMISTRY

0620/51 Paper 5 (Practical), maximum raw mark 40





1 (c) Table of results for Experiments 1–4 mass of solids correctly recorded (1) initial and maximum temperature boxes correctly completed (1) temperature differences correct (1) temperature changes increasing (1) [4] (d) results for Experiment 5 initial and final temperatures completed (1) temperature change completed correctly and shown as negative (1) [2] (e) appropriate scale on y-axis which uses at least half of the grid (1) all points correctly plotted (2), –1 for any incorrect ignore: origin best fit straight line graph drawn with a ruler (1) [4] (f) (i) value from graph (1) extrapolation shown clearly (1) [2] (ii) value from graph (1) shown clearly (1) [2] (g) endothermic (1) [1] (h) lower temperature change (1) greater volume/more acid (1) [2] note: halved = 2 marks (i) room temperature / initial temperature from table (1)

reaction finished / owtte (1) [2]

(j) advantage e.g. comparability of results/fair test (1)

ignore: reference to accuracy or reliability

disadvantage e.g. reaction not finished / temperature still changing (1) [2]




2 tests on liquid A

(a) colourless (1) not: clear and smells acidic/vinegar/sour/pungent/bitter/strong not: sweet [1]

red/orange/yellow (1) pH = 3–6 (1) [2]

(b) bubbles/fizzes/effervesces (1)

lighted splint (1)

pops (1) ignore: hydrogen [3] (c) slow/few (1) bubbles/effervescence/fizz (1) [2] (d) blue/green colour (1) not: precipitate [1] tests on liquid B (e) (i) yellow/orange (1) turns green (1) not: blue [2] (ii) pink/purple (1) turns colourless/decolourises (1) not: clear [2] (f) blue/yellow/orange (1) flame/catches fire/lights (1) [2] (g) ethanoic acid/vinegar (2) [2] (h) organic (1) fuel (1) not: flammable

note: ethanol/alcohol = 2 [2]




0620 CHEMISTRY






1 (a) Table of results for Experiment 1

initial and final volumes and differences completed correctly (1) within ± 2 Supervisor (1)

all results (both tables) to 1 or 2 decimal places (including 0.0) (1) [3]

(b) Table of results for Experiment 2

initial and final volumes and differences completed correctly (1)

titre lower than experiment (1)

within ± 2 Supervisor (1) [3] (c) (i) to speed up the reaction / owtte (1) [1]

(ii) colourless (1) not: clear, to brown / pink / purple / lilac / mauve (1) [2]

(iii) not an acid / alkali reaction or potassium manganate is coloured / self indicating owtte (1) [1]

(d) (i) experiment 1 allow: ecf from results (1) [1]

(ii) experiment 1 (about) 2x volume experiment 2 – quantitative relationship required. allow: ecf from results [1]

(iii) solution B / experiment 1 more concentrated / stronger or converse (1)

(about) 2x as concentrated – quantitative statement (1) [2]

(e) half value from table result for experiment 2 (1) cm3 (1)

half volume / amount (of C) used (1) [3] (f) (both) oxidation (1)

(and) reduction (occur) (1)

accept: answers using definitions of oxidation in terms of: oxygen / hydrogen / electrons / oxidation numbers transfer of electrons scores 2 [2]

(g) advantage: easy to use / quick / convenient (1)

disadvantage: not accurate owtte (1) [2]




2 bubbles / fizz (ignore references to colour / ppt) (1) [1]

(a) pH = 7 (accept any in range 5 to 7, must be a number) (1) [1]

(b) (i) white precipitate (1) dissolves / clears (1) [2]

(ii) white precipitate (1)

Insoluble / does not dissolve (1) (dependent on a ppt having been formed) [2]

(c) no change / colourless solution / no ppt / no reaction (1) [1]

(d) white (1) precipitate (1) [2]

(e) bubbles / fizz / effervescence (1)

limewater (1) milky (1) [3] white (1) precipitate (1) [2]

(f) aluminium (1) sulfate (1) [2]

(g) carbon dioxide (1) [1]

(h) calcium (1) carbonate (1) [2]




0620 CHEMISTRY






1 (b) Table of results

Experiment 1 initial and final volumes completed correctly (1) difference calculated correctly (1) Experiment 2 initial and final volumes and difference completed correctly (1) difference calculated correctly (1) both experiments all results to 1 (or 2) dp, including 0.0 (1) difference in experiment 2, difference in experiment 1 (1) [6]

(c) yellow (1) to orange / pink / red (1) [2]

(d) neutralisation (1) accept: endothermic [1]

(e) experiment 2 (1) allow: ecf on results [1]

(f) (i) (about) 3x as much used in experiment 1 (1) allow: ecf on results [1]

(ii) solution / acid G / 2 (1) [1]

(g) twice value from table result for experiment 2 (1) cm3 (1) [2]

(h) use a pipette / burette [1]

(i) effect none owtte (1)

reason no change in concentration / same amounts (1) owtte [2]




(j) any correct method that would work – precise details not needed

using same method (volume required) with different bases = 0 adding indicator and checking colour = 0

reagents (1) method (1) result (1) [3]

e.g. (to hydrochloric acid) add named metal e.g. Mg, Zn (1)

measure temperature change (1) largest change = more concentrated solution (1)

(to hydrochloric acid) add sodium hydroxide solution (1) measure temperature change (1) largest change = more concentrated solution (1)

to hydrochloric acid add named metal / metal carbonate measure speed of reaction (time to complete/rate of gas production) fastest = more concentrated solution




2 (a) blue / green (1) [1]

(pale) blue / green / greener (1) [1]

(b) blue (1) precipitate (1) [2]

with heat: turns brown (1) then black (1) sharp / vinegar / pungent / strong / sour / bitter smell (1) max 2 [2]

with nitric acid turns green / blue (1) [1]

(c) blue (1) precipitate (1) [2]

with excess: deep blue (1) solution / clear / dissolves (1) [2] (d) (i) solid turns black (1) condensation at top of tube (1)

splint flashes / flame at top of tube (1) max 2 [2]

(ii) effervescence / bubbles / fizz (1)

splint extinguished owtte (1) [2]

(e) vinegar / pungent / sharp / strong / sour / bitter smell (1) [1]

(f) copper (1) ethanoate / organic (1) [2]

(g) carbonate (forms on heating) (1) carbon dioxide (forms) (1) organic / flammable gas given off when heated (1) ethanoate (1) max 2 [2]




0620 CHEMISTRY

0620/61 Paper 6 (Alternative to Practical), maximum raw mark 60




© University of Cambridge International Examinations 2012

1 (a) electrode(s) / anode / cathode(either) (1) allow: electrodes labelled wrong way round not: carbon/platinum

bulb / lamp / light (1) [2]

(b) lighted splint (1) pops (1) glowing splint = 0 [2] (c) graduated test-tube / measuring cylinder (1) not: gas syringe as will not work filled with electrolyte / acid / water inverted over electrode / owtte (1) [2] (d) (i) sodium hydroxide (1) [1]

(ii) universal indicator with pH>7 / litmus turns blue (1) [1] note: mark not awarded if (d)(i) is incorrect

2 (a) to prevent air / oxygen / bacteria entering jar (1) [1] (b) pestle and / or mortar (1) [1] (c) diagram of funnel and filter paper (1) labelled (1) [2] (d) yeast would not work at high temperatures / kills yeast / denatures enzymes / owtte (1) [1]

allow: kills enzyme (e) (i) bubbles / froth (1) [1]

not: gas / CO2 given off / turns cloudy (ii) (collect gas) and measure volume / count bubbles (1) over certain time interval (1) [2] allow: one mark for timing until bubbles / reaction stopped (f) fractional distillation (1) [1]




3 (c) Table of results for Experiments 1–4 mass of solids correctly recorded (1) 1, 2, 3, 5 g initial and maximum temperature boxes correctly completed (1) initial 21, 23, 22, 24 maximum 23, 27, 28, 34 temperature differences correct (1) 2, 4, 6, 10 [3] (d) results for Experiment 5 initial and final temperatures completed 21 and 13 (1)

temperature change completed correctly and shown as negative –8 (1) [2]

(e) all points correctly plotted 3–1 for any incorrect straight line graph drawn with a ruler (1) [4]

(f) (i) value from graph 12 °C ± half small square (1) extrapolation shown clearly (1) allow: ecf [2] (ii) value from graph 4.5 g ± half small square (1) indication shown clearly (1) allow: ecf [2] (g) endothermic (1) [1] (h) lower temperature change (1) 3 °C (1) greater volume/more acid (1) any 2 for [2]

(i) room temperature or initial temperature from table 24 °C (1) reaction finished / owtte (1) [2] (j) advantage, e.g. comparability of results / fair test (1)

ignore: reference to reliability / accuracy

disadvantage, e.g. reaction not finished / temperature still changing / may not reach maximum temperature (1) [2]




4 tests on filtrate (a) colourless (1) [1]

ignore: clear, not: white

(b) white (1) precipitate (1) soluble in excess / dissolves (1) [3] (c) white precipitate (1) Insoluble / does not dissolve (1) [2] (d) white (1) precipitate (1) [2] (e) no reaction / no change / no precipitate (1) [1] (g) transition metal / copper (1) carbonate (1) [2] 5 (a) both lose mass (1) [1]

not: change mass

(b) mass loss increases constantly in graph A (1)

becomes constant in graph B (after about 7–9 hours) (1) mass loss or change is greater in acid/less in alkali (1) [3] (c) goggles / lab coat / tongs / fume cupboard / well ventilated area any two [2]

ignore: reference to hair 6 weigh mixture (1) add excess (1) sulfuric acid (1) heat / stir (1) filter (1) wash (1) dry (1) the carbon / residue reweigh(1) calculate percentage (1) max 6 [6] will not work = 0 ignore: details of evaporation of copper sulfate solution note: must have at least one weighing for 6 marks




0620 CHEMISTRY






1 (a) pestle and / or mortar (1) filter / funnel (1) [2] (b) (i) labelled arrow at liquid in mortar (1) (ii) labelled arrow at liquid in either tube or liquid in funnel or any combination (1) [2] (c) (i) top line labelled (1) [1] (ii) three (1) [1] 2 (a) black (1) [1] (b) (i) copper / Cu (1) (ii) water / H2O (1) accept: steam [2] (c) boiling point / freezing point (1)

100 °C / 0 °C (1) note: do not accept a chemical test [2]




3 (a) table of results for Experiment 1 final and initial volumes and difference completed correctly 26.00, 0.0 and 26.0 (1) to 1 decimal place (1) accept: volumes to 2 d.p. (e.g. 26.00) [2] (b) table of results for Experiment 2 final and initial volumes and difference completed correctly 19.0 and 32.0 (1) 13.0 (1) [2] ignore: decimal places, accept: 19, 32,13, allow: ecf on final and initial volumes (c) (i) colourless not: clear to purple / pink (1) [1] accept: colour change either way round (ii) not an acid / alkali reaction or potassium manganate is coloured or pink / acts as an

indicator / there is already a colour change / owtte (1) [1] (d) (i) experiment 1 (1) allow: ecf on (a) and (b) [1] (ii) experiment 1 is twice the volume of experiment 2 / experiment 2 is half the volume of

experiment 1 (1) note: must be a quantitative comparison, do not allow quotes of figures from table allow: ecf (e.g. 13 times as much as experiment 2) [1]

(iii) solution B / experiment 1 more concentrated / stronger (1) or converse double / twice (1) [2] ignore: reference to reactivity (e) half value from table result for experiment 2 (6.5) (1) allow: ecf cm3 (1) half volume of C used (1) [3] (f) oxidation (1) reduction (1) or: electrons are lost (1) gained (1) transferred (2) [2] accept: oxidation numbers increase (1) decrease (1) accept: hydrogen / H2 / H lost (1) gained (1) accept: oxygen / O2 / O gained (1) lost (1) (g) advantage easy to use / quick / convenient (1) ignore: large volumes disadvantage not accurate / owtte (1) [2]




4 (a) colourless (1) ignore: clear, not: white [1] (b) white (1) precipitate (1) dissolves / clears (1) [3] (c) white precipitate (1) insoluble / does not dissolve (1) [2] (d) no change / colourless solution / no reaction (1) [1] (e) white (1) precipitate (1) [2] (g) carbon dioxide / CO2 (1) [1]

(h) calcium / Ca2+ (1) accept: any Group 2 metals carbonate / CO3

−

2 (1) note: CaCO3 = 2 [2] 5 (a) thermometer diagrams completed correctly (3) –1 each incorrect 23, 29, 35, 41, 39, 35, 31 ignore: decimal places [3] (b) points plotted correctly (3), –1 each incorrect two intersecting straight lines (1) [4] allow: lines extending beyond intercept but must be just two lines and no curves (c) 16 (cm3) ±0.5 (1) any indication (1) [2]

(d) 23 (°C) (1) [1] (e) good insulator or reference to minimising heat losses (1) [1] (f) reaction produced heat or energy (1) accept: reaction is exothermic

reaction finished / reactant(s) used up / KOH used up / neutralised (1) not: acid used up/ neutralised [2] (g) exothermic (1) [1]




6 note: all methods can gain the first three marks but only methods that would give usable results can gain the last three marks

known / same mass / amount of metal (1) known / same volume / amount of acid (1) test both A and B (1) a method of collecting results (1) time or run side by side (1) comparison of results (1)

max 6 [6]




0620 CHEMISTRY






1 (a) (i) arrow / label underneath solid in tube (1) (ii) arrow / label in U-tube below level of ice (1) [2] (b) red / brown (1) [1] (c) water collected only from the reaction / owtte (1) [1] (d) test anhydrous / white copper sulfate / cobalt chloride (paper) (1) result turns blue / pink (1) note: do not allow physical tests [2] 2 (a) fizz / bubbles / effervescense (1) [1] (b) carbon / graphite (1) [1] (c) electrolysis (1) [1] (d) (i) alkali formed (1) sodium hydroxide formed (2) [2] (ii) colourless / red (1) chlorine bleaches / chlorine is an acidic gas / acid produced (1) [2]




3 (b) table of results initial readings completed correctly (1) 0.0, 9.0 final readings completed correctly (1) 39.0, 22.0 all readings to 1 decimal place (1) differences completed correctly (1) 39.0, 13.0 [4] (c) yellow (1) to orange / pink (1) [2] (d) neutralisation (1) allow: endothermic [1] (e) Experiment 2 (1) allow: ecf [1] (f) (i) three times as much used in Experiment 1 (1) not: ecf [1] (ii) solution / acid G / 2 (1) [1] (g) twice value from table result for experiment 2 / 26 (1) cm3 (1) [2] (h) use a pipette/burette [1] (i) to remove acid F / clean (1) water would dilute acid G / owtte (1) [2] (j) effect none / owtte (1) reason no change in concentration / owtte (1) [2]




(k) any correct method that would work- precise details not needed using same method with different bases = 0 reagents (1) method (1) result (1) [3] not: method using indicators e.g. * to hydrochloric acid add named metal, e.g. Mg, Zn (1) measure temperature change (1) largest change = strongest / more concentrated solution (1) * to hydrochloric acid add sodium hydroxide solution (1) measure temperature change (1) largest change = strongest solution (1) * rate experiment add acid to appropriate reagent (1) method of rate measurement, e.g. volume of gas (1) conclusion (1) 4 tests on solid H (a) blue / green (1) [1] (b) blue (1) precipitate (1) [2] (c) blue (1) precipitate (1) [2] with excess deep blue (1) solution / clear / dissolves (1) [2] (d) forms a carbonate on heating / carbon dioxide present (1) organic / ethanoate (1) [2]




5 (a) volumes completed correctly in table (2), –1 each incorrect 0, 38, 59, 73, 78, 79, 79 [2] (b) appropriate scale for y-axis (1) points plotted correctly including origin (2) smooth curve (1) [4]

(c) 90 s (1) indication (1) [2]

(d) sketch to right of graph (1) levelling out at 39–40 cm3 (1) [2] (e) particles moving slower / have less energy (1) fewer collisions (1) [2]

6 variety of ways that could be used generally appropriate solvent for named solid (1) evaporate off solvent (1) mention of these three terms at least once

filter (1) wash (1) dry (1) appropriate solvent for second named solid (1) and filter lastly wash and dry remaining solid (1) example; add cyclohexane to the mixture to dissolve W (1) filter (1) wash (1) evaporate off cyclohexane (1) to residue add cold water to dissolve Y (1) evaporate off water (1) wash (1) dry (1) residue is X (1)

max 6 [6]

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0620 CHEMISTRY - Max Papersmaxpapers.com/wp-content/uploads/2012/11/0620_s13_ms_all.pdf · 0620 CHEMISTRY 0620/11 Paper 1 ... NOTE: minimum of 6 (O) ... Page 6 Mark Scheme Syllabus