® IGCSE is the registered trademark of Cambridge International Examinations. CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 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 October/November 2015 series for most Cambridge IGCSE ® , Cambridge International A and AS Level components and some Cambridge O Level components.
86
Embed
0620 CHEMISTRY - maxpapers.commaxpapers.com/wp-content/uploads/2012/11/0620_w15_ms_all.pdf · 0620/11 Paper 1 (Multiple Choice), maximum raw mark 40 ... Page 2 Mark Scheme Syllabus
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/12 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/13 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
3(b)(i) positive electrode / anode in box on left; negative electrode / cathode in upper box on right; electrolyte / named suitable electrolyte in lower box on right; 3 correct = [2] 1 or 2 correct = [1]
1 1
3(b)(ii) cathode / negative electrode; 2
3(c)(i) the positive electrode: chlorine; the negative electrode: nickel;
6(b) bromine / bromine water / aqueous bromine; decolourised / goes from orange to colourless;
1 1
6(c)(i) double bond; 1
6(c)(ii) poly(ethene) / any other addition polymer; 1
6(d) it is a molecule / covalent compound; 1
6(e) any two from: carbon or soot / carbon monoxide / water; 2
6(f) alcohols / first box ticked; 1
Question Answer Marks
7(a) any five from:
• 11 electrons;
• electrons – (negatively) charged;
• electrons outside nucleus in shells;
• nucleus contains protons and neutrons;
• protons – (positively) charged;
• neutrons no charge;
• 11 protons;
• 12 neutrons;
• electron arrangement 2,8,1 / 1 electron in outer shell;
5
7(b)(i) 2 (NaOH); 2 (H2O);
1 1
7(b)(ii) substance containing carbon and hydrogen only / substance containing carbon and hydrogen and no other element; 1
7(b)(iii) 70; 1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/22 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
3(a)(i) gives off bubbles rapidly / fast / many bubbles; disappears quickly;
11
3(a)(ii) zinc; 1
3(a)(iii) too reactive / high in the electrochemical / reactivity series; 1
3(b) oxygen removed from barium oxide / it loses oxygen; 1
3(c)(i) use pH meter and pH above 7 / (red) litmus turns blue; 1
3(c)(ii) barium chloride; water;
11
3(d)(i) burette; 1
3(d)(ii) any two from:
• starts off at high / alkaline pH / pH above 7;
• pH decreases / gets more acidic / less alkaline / becomes neutral;
• ends up at acidic pH / pH below 7;
2
3(e) two electrodes dipping into the electrolyte; electrodes correctly connected to battery / power supply; correct labels for electrodes and power supply battery;
111
Question Answer Marks
4(a)(i) measure volume of gas / measure amount of gas; gas collected in the measuring cylinder; at different times / use of stopclock to measure time;
111
4(a)(ii) faster reaction / rate increases; 1
4(b)(i) same concentration of acid; same mass of iron; same size of iron pieces;
5(d)(i) aluminium is good conductor; steel is strong / core is strong;
11
5(d)(ii) copper is cheap(er) (than silver) / silver is (more) expensive; 1
Question Answer Marks
6(a)(i) ring around OH group; 1
6(a)(ii) unsaturated and has double bonds; 1
6(b)(i) condenser; 1
6(b)(ii) any characteristic of a mixture, e.g. can be separated by physical means / has variable composition / properties are the average of those of the components;
1
6(b)(iii) geraniol floats on top of the water; 1
6(c)(i) structure of ethanol drawn correctly with all atoms and bonds; 1
• electron arrangement [2,2] / two electrons in outer shell;
5
7(b) BeCl 2; 1
7(c)(i) 43 correct atomic masses only = [1]
2
7(c)(ii) global warming / greenhouse effect / effect of global warming, e.g. rise in sea level / desertification / more extreme weather / climate change;
1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/23 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
1(b) substance containing (two or more) different atoms bonded / substance containing (two or more) different atoms combined; 1
1(c) in light bulbs / as an inert atmosphere / welding; 1
1(d) 3 (Mg) and N2; 1
Question Answer Marks
2(a)(i) plastics; 1
2(b) third box ticked / exothermic; 1
2(c) 4; 1
2(d)(i) speed up the reaction / increase reaction rate; 1
2(d)(ii) carbon dioxide; water;
11
2(e) any two from: • sulfur (oxidises / burns) to form sulfur dioxide; • acid rain / acidic gas formed; • effect of acid rain, e.g. kills animals in ponds (or lakes) / kills plants / soil demineralisation / erodes limestone buildings / iron
structures corroded;
2
2(f)(i) alkane(s); 1
2(f)(ii) colourless / liquid at room temperature / low melting point; 1
3(d)(ii) idea that pH increases slowly at first ; idea of sudden increase at around 18 cm3 ; idea of pH increasing at a slower rate in the more alkaline region;
4(a) measure the volume of gas; in a (measuring) cylinder; at different times;
111
4(b)(i) increases then decreases; comment on the curve, e.g. rate not constant at first / peak (or maximum) at 60 hours / rate of decrease less than rate of increase (around the maximum);
11
4(b)(ii) 0.29 (cm3 CO2 per hour); 1
4(b)(iii) any two from: • higher temperature (R: temperatures above 40 °C); • increase concentration of glucose; • increase amount of yeast;
2
4(c) M1 correct method, e.g. add litmus / add sodium hydroxide / add sodium carbonate / measure pH; M2 correct outcome, e.g. litmus turns red with acid / no change of litmus with ethanol / pH below 7 with acid / pH 7 with ethanol / acid reacts with sodium hydroxide or sodium carbonate / ethanol does not react with sodium hydroxide or sodium carbonate;
11
Question Answer Marks
5(a) any four from: • particles in the liquid slide over each other / move slowly / restricted movement; • particles in the liquid not regularly arranged / randomly arranged; • particles close together in liquid; • in the gas particles arranged randomly / are anywhere; • in the gas particles move from place to place / move freely / move fast; • particles far apart in the gas;
4
5(b)(i) liquid; temperature above melting point but below boiling point;
11
5(b)(ii) copper and iron; both have high melting points ;
5(c)(ii) idea of layer stopping air or water getting to the surface / idea of blocking reaction with the surface of the iron, e.g. stops air or oxygen getting to surface / blocks water or moisture getting to the iron;
1
5(d)(i) iron chloride / iron(II) chloride; hydrogen;
7(a) any five from: • 17 protons; • 18 neutrons; • 17 electrons; • protons positively charged; • neutrons no charge • electrons negatively charged; • electrons outside the nucleus in shells; • nucleus contains protons and neutrons; • electron arrangement 2, 8, 7 / 7 electrons in the outer shell;
5
7(b) sodium atoms each lose an electron / sodium has one more proton than electrons; chlorine atoms each gain an electron / chlorine has one more electron than protons;
11
7(c)(i) iodine formed; 1
7(c)(ii) chlorine is more reactive than iodine / chlorine is higher in the reactivity series than iodine; 1
7(d)(i) C2ClF5; 1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/31 Paper 3 (Extended 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
2(a) add a (dilute) acid; filter; copper does not react or dissolve / zinc reacts or dissolves or forms a salt;
111
2(b) diffusion (through a membrane); nitrogen diffuses faster; because it has the smaller Mr; or (turn into) liquid; (fractional) distillation; different boiling points; or burn a named substance to make non-gaseous product; oxygen reacts / nitrogen does not react; name of product of combustion;
3
2(c) chromatography; use a locating agent / the two acids move at different rates / alanine travels faster / alanine higher up paper / travels further;
11
2(d) add sodium hydroxide solution; filter; zinc hydroxide (is amphoteric it) will react or will dissolve / magnesium hydroxide does not react or does not dissolve;
3(c) moves equilibrium to right; increases yield (of sulfur trioxide) / uses up more sulfur dioxide;
11
3(d)(i) moves equilibrium to left; (forward reaction) exothermic;
11
3(d)(ii) decrease rate; molecules have less energy / move slower; fewer collisions (per second) / fewer particles have the activation energy / fewer collisions have the activation energy;
111
3(e)(i) moves to right; 1
3(e)(ii) high yield at 2 atm; 1
3(f) vanadium(V) oxide / vanadium pentoxide; 1
3(g) M1 dissolve / react sulfur trioxide in (concentrated) sulfuric acid; add water to product of M1;
11
Question Answer Marks
4(a)(i) any two from:
• shortage of sites / landfill sites fill up;
• visual pollution / litter;
• danger to wild life;
2
4(a)(ii) (produce) toxic gases or CO or HCl or HF / carbon dioxide / greenhouse gases; 1
4(c)(i) CH2=CHCH3 double bond is shown; rest of structure correct;
2
4(c)(ii) ester; 1
4(c)(iii) (carboxylic) acid; alcohol;
11
4(d) addition – polymer only product / only one product; condensation – (polymer and) simple molecule / water / hydrogen chloride made; polymer A is an addition polymer and polymer B is a condensation polymer;
111
Question Answer Marks
5(a)(i) adds up to 100%; 1
5(a)(ii) M1 55.85/12 and 6.97(/1) and 37.2/16; or evaluation 4.650 6.970 2.325; M2 C2H3O; correct answer with no working = [2]
1
1
5(a)(iii) M1 (86/)43; M2 C4H6O2; correct answer with no working = [2]
6(a)(iii) SiO2 does not react with or dissolves in or neutralise an acid or acidic oxide; SiO2 does react with or dissolve in or neutralise an alkali or base or basic oxide;
11
6(b) carbon dioxide has a simple molecular structure; 1
7(a)(i) step 2 and it is electron gain / oxidation state decreases; 1
7(a)(ii) silver (ion) and it accepts electrons / gets reduced / oxidation state decreases; 1
7(b) prediction: the ‘not covered’ section will be black; the ‘covered in thick card’ section will be white / cream; the ‘covered in thin card’ section will be grey; explanation: the more light, the more silver ions are reduced;
one correct –O– link between rectangles; two correct glucose units with continuation bonds;
11
7(c)(iv) the reaction of glucose with oxygen to release (carbon dioxide and water and) energy; or the reaction of glucose in a biological system to release energy;
1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/32 Paper 3 (Extended 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
2(a)(i) combustion / burning of a motor vehicle fuel or a named fuel which can act as a motor vehicle fuel; incomplete combustion would produce CO; complete combustion would produce CO2;
2(a)(iii) nitrogen and oxygen react or combine; at high temperatures or in presence of spark;
2
2(a)(iv) it reacts or combines with oxygen / NO + ½O2 → NO2; 1
2(b) any two from:
• acid rain is formed;
• lowers pH or acidifies lakes / rivers or kills fish / aquatic animals;
• changes composition of soils or reduces fertility of soil or reduces crop yields / deforestation or kills crops or trees or plants or leaves / lowers pH of soil or increases acidity of soil;
• attacks (limestone) buildings or statues; attacks metal (structures) / bridges;
Zn → Zn2+ + 2e–; zinc ions are removed (from solution) and replaced (into solution); at the same rate / speed;
6
3(d)(i) copper; 1
3(d)(ii) any two from:
• hard(er) / less malleable;
• strong(er);
• (better) appearance;
• (more) resistant to corrosion;
2
3(e)(i) steel (or iron) is exposed to oxygen and water; 1
3(e)(ii) Zn more reactive than Fe (allow steel); Zn loses / transfers electrons (more readily) and forms (+ve) ions (in preference to Fe); Fe (allow steel) is more reactive than Cu; Fe loses / transfers electrons (more readily) and forms (+ve) ions (in preference to Cu);
5(a) as a reducing agent; source of heat / energy;
2
5(b) Fe2O3 + 3CO → 2Fe + 3CO2
species; balancing;
2
5(c) silica reacts with limestone or calcium oxide; to form a slag or calcium silicate or CaSiO3; (liquid) slag floats (above molten iron);
3
5(d) blow or pass oxygen through (molten) iron; C + O2 → CO2; carbon dioxide escapes or carbon dioxide is a gas;
3
Question Answer Marks
6(a) the number of e– gained or lost = numerical value of oxidation state; any two from:
• Na to Al (Si) lose e–;
• (Si) P to Cl gain e–;
• Si gains and loses e– / Ar neither gains nor loses e–;
1
2
6(b) M1 positive ions / cations / metallic ions; the (correct) particles named in M1 are arranged in a lattice / rows / layers; sea of electrons / delocalised electrons;
3
6(c) they have mobile electrons; 1
6(d) chlorine; 1
6(e) strong covalent bonds ; in a giant lattice / macromolecule / giant (structure);
• ionic bonds are strong and intermolecular forces are weak;
• PCl 3 reacts with water and NaCl does not;
2
6(g) MgO will react with / dissolve in / neutralise hydrochloric acid / acid / acid oxide; if amphoteric, MgO will react with or dissolve in or neutralise hydrochloric acid or acid or acid oxide and MgO will react with dissolve in or neutralise sodium hydroxide or alkali or base or basic oxide; MgO will not react with or dissolve in or neutralise sodium hydroxide or alkali or base or basic oxide = [2]
2
6(h)
Mg
x
x
x
2+
x
x x
x
x O
2-
x
x
magnesium with 8 or 0 outer shell electrons; oxygen with 8 outer shell electrons and 2 indicated differently from the other 6 and these 2 electrons must match the Mg electrons if these have been shown; correct charges;
3
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS
Cambridge International General Certificate of Secondary Education
MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/33 Paper 3 (Extended 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 October/November 2015 series for most Cambridge IGCSE
®, Cambridge International A and AS Level components and some
1(d) any two from: making steel; making paper; textiles; generating electricity / energy / power / turbines; HEP; water mills; steam power (e.g. steam engines); geothermal power; agriculture; livestock; irrigation; hydration of alkenes / manufacture of ethanol / alcohols; manufacture of sulfuric acid / Contact process; manufacture of hydrogen; solvent / dissolving; coolant / cooling; cleaning / washing; (supply of) drinking (water); central heating; production of slaked lime; cooking;
3(b)(i) correct direction (going towards negative electrode); 1
3(b)(ii) Li+ + e– → Li / Li+ → Li – e–; 1
3(b)(iii) 2Br– → Br2 + 2e– / 2Br– – 2e– → Br2
formulae; balancing;
2
3(b)(iv) Br– / bromide (ion);
electron lost / donated electrons / increased oxidation state / increased oxidation number / oxidation numbers changed from –1 to 0 / increased valency;
3(c) M1 (gas) hydrogen (given off at cathode) / H2; M2 hydroxide ions / lithium hydroxide / OH–
/ LiOH are alkali(ne);
M3 2LiBr + 2H2O → 2LiOH + H2 + Br2; or
2H+ + 2e– → H2 / 2H+ → H2 – 2e–; or
2Br– → Br2 + 2e– / 2Br– – 2e– → Br2;
or
2H+ + 2Br– → H2 + Br2;
3
Question Answer Marks
4(a)(i) any three from:
• (same) general (molecular) formula;
• (consecutive members) differ by CH2;
• same functional group;
• common (allow similar) methods of preparation;
• same / similar chemical properties / (chemical) reactions;
3
4(a)(ii) CnH2n alkene; CnH2n+2 alkane;
1
1
4(a)(iii) alkanes all or only (C–C) single bonds / no double bonds / no multiple bonds; alkenes (at least one) C=C / double bond / multiple bond;
1
1
4(b)(i) heat / high temperature / temperature between 450 °C and 800 °C; catalyst / named catalyst, e.g. zeolites or alumina or aluminium oxide or aluminosilicates or silica or oxides of chromium; or high pressure / pressure in range of 2–70 atm; or steam; absence of air / oxygen;
2
4(b)(ii) any correct equation producing an alkane and an alkene adding up to seven carbon atoms in the products; 1
4(b)(iii) any correct equation producing two alkenes and hydrogen, e.g. → C2H4 + C5H10 + H2 / C3H6 + C4H8 + H2; 1
4(b)(iv) alkenes: more useful than alkanes / used to make polymers or plastics / used to make chemicals / petrochemicals; or alkanes: (balance the demand for different) fuels / increase petrol (fraction) or hydrogen / produce lighter fractions from heavier fractions or suitable example, e.g. naphtha to gasoline / more useful smaller molecules or more demand for smaller molecules or more demand for smaller fractions / used as fuel / used to make ammonia / used in Haber process / used in hydrogenation of vegetable oils / used to make HCl ;
5(a)(ii) strong acid completely or fully ionises / completely or fully dissociates / completely or fully splits into ions; weak acid partially or incompletely ionises or dissociates or splits into ions / does not ionise fully;
5(d)(ii) 2NaOH + H2SO4 → Na2SO4 + 2H2O Na2SO4; rest of equation correct; or H+ + OH– → H2O H2O as the only product on the right hand side; rest of equation correct; or NaOH + H2SO4 → NaHSO4 + H2O NaHSO4; rest of equation correct; or OH– + H2SO4 → HSO4
– + H2O HSO4
–; rest of equation correct;
2
5(d)(iii) Fe + H2SO4 → FeSO4 + H2; FeSO4; rest of equation correct; or Fe + 2H+ → Fe2+ + H2; Fe2+; rest of equation correct; or 2Fe + 3H2SO4 → Fe2(SO4)3 + 3H2; Fe2(SO4)3; rest of equation correct; or 2Fe + 6H+ → 2Fe3+ + 3H2; Fe3+; rest of equation correct;
6(e) copper sulfate (solution); add manganese / Mn to solution; copper displaced or forms / blue colour changes; or (a solution of) an iron salt or a zinc salt; add copper and manganese to each; only manganese reacts / displaces; or (a solution of a) manganese salt and a copper salt; add, e.g. iron / zinc; copper (displaced) and manganese not; or to a (dilute) acid / any named acid / water / steam; add Mn and Cu / both metals to the liquid; rate faster or shorter time or more bubbles or more hydrogen or more gas with Mn or with the more reactive metal / reaction only with Mn or with the more reactive metal; or copper oxide; add manganese and heat; evidence of reaction; or burn manganese and copper / both elements; in air / oxygen; Mn or more reactive metal burns brighter / only Mn or more reactive metal burns / evidence that manganese reacts faster; or add carbon; to both metal oxides and heat; evidence that reaction occurs with copper oxide more readily / least reactive metal oxide;
or both metal nitrates or carbonates; heat; evidence that manganese compound is most stable / most reactive compound is most stable; or (electrochemical) cell / use of voltmeter / electrolyte; copper and manganese (as electrodes); manganese is the negative terminal;
6(f) physical properties any three from: hard; strong; high density; malleable; ductile; sonorous; shiny; high melting point / high boiling point; (good) conductor (of heat/electricity); forms coloured compounds / coloured ions / coloured salts; chemical properties any two: catalytic behaviour; more than one or different or variable oxidation state or oxidation number or valency / variable charges / many differently charged ions; forms complex (ions); forms coloured compounds / coloured ions / coloured salts; amphoteric oxide / amphoteric / basic oxide / alkaline oxides / acidic oxide; (other metallic reactions) with acids / water / steam; reducing agent / electron donor / reacts with non-metal to form ionic compound / forms positive ions;
7(a) moles of KOH used ( = 0.025 × 2.53 =) 0.06325 / 0.063; number of moles of H2SO4 needed to neutralise the KOH = 0.031625 / 0.032; concentration of dilute sulfuric acid = 1.121/1.1 (mol / dm3);
3
7(b)(i) repeat experiment using same volume / amount of (same) H2SO4; and same volume / amount of (same) KOH; or (add activated) charcoal / carbon; filter out the charcoal; or mix volumes / amounts of H2SO4 and KOH in the ratio 1:2; of the same concentration;
2
7(b)(ii) make solution of potassium sulfate as above; add same volume / amount of acid again; or same volume / amount of KOH; add double the volume / amount of H2SO4; 25 cm3 KOH + 56.4 cm3 H2SO4 = [2] or same volume / amount of H2SO4; add half the volume / amount of KOH; 12.5 cm3 KOH + 28.2 cm3 H2SO4 = [2] or mix equal volumes / amounts of H2SO4 and KOH ; of the same concentration; mix solutions containing equal numbers moles of KOH and H2SO4 = [2]
7(c) test: reactive metal / name or formula of suitable metal, e.g. Mg / Fe / Zn; result: bubbles or gas or hydrogen or H2 evolved / dissolves; test: insoluble carbonate or name / formula of suitable insoluble carbonate, e.g. CaCO3; result: bubbles or gas or carbon dioxide or CO2 evolved / dissolves provided that carbonate is insoluble; test: alkali or name / formula of suitable alkali, e.g. NaOH / KOH; result: temperature change; test: alkali or name / formula of suitable alkali, e.g. NaOH / KOH and indicator; result: colour change; test: insoluble base or name / formula of suitable insoluble base; result: dissolves; test: indicator, e.g. blue litmus; result: colour change (colour need not be specified); test: measure pH / pH paper / UI paper / pH meter; result: pH 0–3 or indicator red / orange or pH lower than pH of K2SO4;
2
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/51 Paper 5 (Practical), maximum raw mark 40
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 51
Abbreviations used in the Mark Scheme • ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 51
2(c) green precipitate; brown colour on sides / top of tube;
1 1
2(d) green precipitate; 1 2(e) (pink to) colourless;
brown; precipitate;
1 1 1
2(f) white precipitate; 1 2(g) brown precipitate;
bubbles; litmus paper turns blue / pH 10–12;
1 1 1
2(h) yellow; precipitate;
1 1
2(i) iron; (II); chloride;
1 1 1
2(j) silver / lead; nitrate;
1 1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/52 Paper 5 (Practical), maximum raw mark 40
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 52
Abbreviations used in the Mark Scheme • ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 52
2(c) green precipitate; brown colour on sides / top of tube;
1 1
2(d) green precipitate; 1 2(e) (pink to) colourless;
brown; precipitate;
1 1 1
2(f) white precipitate; 1 2(g) brown precipitate;
bubbles; litmus paper turns blue / pH 10–12;
1 1 1
2(h) yellow; precipitate;
1 1
2(i) iron; (II); chloride;
1 1 1
2(j) silver / lead; nitrate;
1 1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/53 Paper 5 (Practical), maximum raw mark 40
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 53
Abbreviations used in the Mark Scheme • ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 53
1(a) initial and final volumes completed correctly; to 1 d.p.; comparable to Supervisor’s result (±0.3 cm3);
1 1 1
1(b) initial and final volumes completed correctly; to 1 d.p.; comparable to Supervisor’s result (±0.3 cm3);
1 1 1
1(c)(i) to remove M / residue / impurities / to clean it; 1 1(c)(ii) to remove water / so N is not diluted; 1 1(d)(i) colourless / pale green to pink; 1 1(d)(ii) there is already a colour change / self-indicating / it goes pink / owtte; 1 1(e)(i) Experiment 1 / solution M 1 1(e)(ii) volume for Experiment 1 is twice volume for Experiment 2 / volume for Experiment 2 is half volume for
Experiment 1; 1
1(e)(iii) solution N is twice as concentrated / strong ora; 2 1(f) half value from result in table for Experiment 2;
half volume (of L) used; 1 1
1(g) advantage: easy to use / quick / convenient; disadvantage: not accurate owtte;
1 1
Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 53
2(g) white / grey / light blue (solid); 1 2(h) initial temperature;
final temperature higher than initial; turns blue;
1 1 1
2(i) blue; precipitate;
1 1
2(j) blue precipitate; dissolves / soluble / solution; deep / dark / royal blue (solution);
1 1 1
2(k) any two from: • hydrated / water; • acid; • organic;
2
2(l) copper (ions present); 1
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/61 Paper 6 (Alternative to Practical), maximum raw mark 60
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 61
• ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 61
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/62 Paper 6 (Alternative to Practical), maximum raw mark 60
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 62
• ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 62
6 Method 1: Monitoring the reaction of the metal with acid 6 from:
• named acid; • same or stated volume of (same concentration of) acid; • fair test idea, i.e. same surface area / size / mass / amount metal; • measure volume of gas / count bubbles / temperature change / observe complete reaction; • suitable reference to time; • conclusion / comparison, e.g. most effervescence = most reactive;
Method 2: Displacement reaction 6 from:
• react each metal; • with named acid; • to prepare salt solution of each; • react each metal with each solution of salt; • observe if displacement occurs; • conclusion / comparison;
6
® IGCSE is the registered trademark of Cambridge International Examinations.
CAMBRIDGE INTERNATIONAL EXAMINATIONS Cambridge International General Certificate of Secondary Education MARK SCHEME for the October/November 2015 series
0620 CHEMISTRY
0620/63 Paper 6 (Alternative to Practical), maximum raw mark 60
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 October/November 2015 series for most Cambridge IGCSE®, Cambridge International A and AS Level components and some Cambridge O Level components.
Page 2 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 63
• ; separates marking points • / separates alternatives within a marking point • () the word or phrase in brackets is not required but sets the context • A accept (a less than ideal answer which should be marked correct) • I ignore (mark as if this material were not present) • R reject • ecf credit a correct statement that follows a previous wrong response • ora or reverse argument • owtte or words to that effect (accept other ways of expressing the same idea)
Page 3 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 63
2(e) coating will not stick / be even / dirt or grease will be trapped; 1 2(f) spoon not completely immersed in electrolyte / only half of spoon will be plated; 1
Page 4 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 63
3(a) all temperatures correctly recorded: 30, 35, 33, 29 4 correct = 2 3 correct = 1 2 or fewer correct = 0 temperature rises: 5, 10, 8, 4;
2
1 3(b) idea of fair test / comparability of results / only one variable / control (variable); 1 3(c) 4 points plotted correctly, ± half a small square;
two intersecting straight lines drawn with a ruler; through points 1 and 2 and 3 and 4, extrapolated to intersect;
1 1 1
3(d)(i) 11 °C; 1 3(d)(ii) C = 28 and D = 22;
cm3; 1 1
3(e) 22 (°C) / 2 × value from (d)(i); 1
Page 5 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 63
4(b) correct table of results for Experiment 1: final volumes, initial volumes and difference: 10.8 0.0 10.8; all readings in both tables to 1 decimal place;
1
1 4(c) correct table of results for Experiment 2: final volumes and initial volumes: 12.3 6.9;
difference correct: 5.4;
1
1 4(d)(i) to remove M / residue / impurities / to clean it; 1 4(d)(ii) to remove water / so N is not diluted; 1
4(e) there is already a colour change / self-indicating / it goes pink / owtte; M and N change colour or show when the reaction is complete;
1
1 4(f)(i) Experiment 2 / solution M / the first titration; 1 4(f)(ii) Experiment 2 uses 2 × volume of Experiment 3 ora; 1
4(f)(iii) twice as concentrated / strong ora; 2 4(g) half value from table result for Experiment 3 / 2.7;
half volume (of L) used; 1 1
4(h) advantage easy to use / quick / convenient; disadvantage not accurate owtte;
1 1
Page 6 Mark Scheme Syllabus Paper Cambridge IGCSE – October/November 2015 0620 63
• uses different (at least two) concentrations of sulfuric acid; • made by diluting with water; • same total volume of (diluted) sulfuric acid; • same mass / amount / size / length / surface area of magnesium (ribbon); • measure time (or run at the same time); • for magnesium to dissolve or react or disappear / y cm3 gas to collect / volume collected (set time) / bubbles
to stop / mass to decrease by x g / mass to stop decreasing; • compare times of reaction / results;