IGCSE Chemistry 4437 / 5H Mark Scheme (Final) November 2007 IGCSE IGCSE Chemistry (4437/5H) Edexcel Limited. Registered in England and Wales No. 4496750 Registered Office: One90 High Holborn, London WC1V 7BH
General Marking Guidance All candidates must receive the same treatment. Examiners must mark the first candidate in exactly the same way as they mark the last. Mark schemes should be applied positively. Candidates must be rewarded for what they have shown they can do rather than penalised for omissions. Examiners should mark according to the mark scheme not according to their perception of where the grade boundaries may lie. There is no ceiling on achievement. All marks on the mark scheme should be used appropriately. All the marks on the mark scheme are designed to be awarded. Examiners should always award full marks if deserved, i.e. if the answer matches the mark scheme. Examiners should also be prepared to award zero marks if the candidate s response is not worthy of credit according to the mark scheme. Where some judgement is required, mark schemes will provide the principles by which marks will be awarded and exemplification may be limited. When examiners are in doubt regarding the application of the mark scheme to a candidate s response, the team leader must be consulted. Crossed out work should be marked UNLESS the candidate has replaced it with an alternative response.
1 (a) (i) C / F (ii) A and B (iii) E 1 (b) Poly(()ethene()). Accept polythene/polyethylene correct repeat unit H Or any multiple length C (2 + carbons) H continuation bonds or.... (only if first mark awarded) Ignore brackets and n or other subscripts Total 6 marks 2 (a) 0 for mass Particle Relative mass Relative charge Electron 1 1 1-1 1840 2000 1850 1 1836 Neutron 0 / nil Proton 1 (4) Ignore negligible
2 (b) (i) helium /carbon / nitrogen / oxygen / neon / magnesium / silicon / sulphur / calcium (ii) silicon (iii) hydrogen Max penalty 1 if give symbols for all 3 rather than names 2 (c) 7 2 (d) (i) full / complete ignore saturated (ii) unreactive/inert/do not undergo reactions Total 10 marks 3 (a) zinc is less reactive than magnesium Magnesium is more reactive than Zinc Or correct reference to positions in reactivity series It is more reactive
3 (b) (i) Fe + CuSO 4 FeSO 4 + Cu reagents products incorrect balancing = -1 be generous with cases (ii) (dark) grey to pink-brown blue to green (2) (2) Ignore additional information 3 (c) hydrogen more reactive than copper hydrogen less reactive than iron Iron(II) or Copper (II) Hydrogen between Fe + Cu for both marks Total 9 marks 4 (a) (i) shared electron pair all other electrons correct (ignore inner shells even if wrong) (ii) bottom box crossed 4 (b) same number of electrons / same electronic configurations Same protons negates
4 (c) add sodium hydroxide (solution)/ammonia solution/ ammonium hydroxide green ppt/solid/suspension Orange/brown/orange-brown/foxy brown/rusty brown/red-brown ppt/ solid/suspension If miss out ppt then give 1 mark for 2 correct colours result marks only given if test correct Powder/crystals/bits Orange/rusty/red Total 7 marks 5 (a) (X) chlorine / Cl 2 (Y) sodium / Na (Z) aluminium / Al 5 (b) Y and Z / Na and Al 5 (c) yellow
5 (d) burns with a squeaky pop 5 (e) (products) Z 2 (SO 4 ) 3 + H 2 O (balancing) - 3-3 Total 8 marks 6 (a) C n H 2n+2 6 (b) similar chemical properties / same functional group gradation in physical properties neighbouring members differ by CH 2 Max 2 (2) 6 (c) no double bonds / only single bonds
6 (d) contains oxygen / not just carbon and hydrogen 6 (e) Acceptable Answers H H H H H H C C C C C H pentane H H H H H Mark H H H H H C C C C H (2-)methylbutane H CH 3 H H H CH 3 H H C C C H (2,2-)dimethylpropane H CH 3 H (any two structures and matching names for 1 each) (4) Total 9 marks 7 (a) ammonia hydrogen chloride
7 (b) (i) ammonia (ii) NH 4 + (iii) NH 4 Cl + NaOH NaCl + H 2 O + NH 3 reactants products 7 (c) (i) silver chloride (ii) Cl (iii) (products) AgCl + NH 4 NO 3 (state symbols) aq aq s aq Total 10 marks 8 (a) 2,7 2.8 8 (b) (ion) 2 and 8 or shown on diagram 2+ shown
8 (c) F 2 / fluorine gains electrons 8 (d) positive and negative ions / oppositely charged ions 8 (e) fluorine (molecules) attracted by (weak) intermolecular forces which are (much) weaker than ionic bonds/bonds in MgF 2 8 (f) (i) 100 (78.6 + 10.1) = 11.3 (ii) (24 0.786) + (25 0.101) + (26.113) = 24.3 Total 12 marks
9 (a) decreases increases increases no change (4) 9 (b) rate increases (reactant) particles closer together/more particles in given volume molecules/particles collide more frequently/ more collisions per second Rate same/rate decreases = 0/3 atoms If no mention of particles/molecules max 1 for explanation 9 (c) recycled / put back into reactor Used again 9 (d) (i) oxidation / redox/ accept exothermic (ii) 2NO + O 2 2NO 2 all formulae correct balancing
9 (e) NH 4 NO 3 9 (f) phosphorus potassium Phosphate Total 14 marks
10 (a) nitric acid KOH + HNO 3 KNO 3 + H 2 O 10 (b) (i) (K 2 O) M r = 94 (KOH) M r = 56 (ii) (18.8 94 = 0.20 mol (0.20 2 56 =) 22(.4) (g) (answer of 11(.2) scores 1) 10 (c) RbOH + HCl RbCl + H 2 O Total 7 marks Paper total 90 marks