Mark Scheme (Results) November 2010

Transcription

1 Scheme (Results) November 200 IGCSE IGCSE Chemistry (4335) Paper F Edexcel Limited. Registered in England and Wales No Registered Office: One90 High Holborn, London WCV 7BH

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3 IGCSE CHEMISTRY 4335/F NOVEMBER 200 SECTION A Question Notes Total a M 2 b M argon / Ar / calcium / Ca c M oxygen / sulphur / selenium / tellurium / polonium d M He / Ne / Ar / Kr / Xe / Rn e M tin / Sn Question 2 a M neutrons b M nucleus c M negative d M protons and neutrons Accept in either order e M neutrons f M identical

4 Question 3 a i M carbon + oxygen carbon dioxide ii M carbon dioxide b i M cross in box 3 M2 cross in box 5 ii M painting / galvanising / coating with zinc c M aircraft bodies / cooking pans / overhead power cables Uses: 2 M2 Any two for mark each M3 M4 2 aircraft bodies low density cooking pans good conductor of heat overhead power cables good conductor of electricity Properties: Any two for mark each Property must match use Question 4 a M cross in box b i M cross in box A / F ii M cross in box F iii M cross in box F iv M cross in box B c M car/vehicle (fuel) M2 kerosene / paraffin M3 roads / roofs d i M oxygen M2 water / steam ii M cross in box 3

5 Question 5 a i M melting ii M Z iii M heat / energy b M solid / ice c i M H 2 O(s) ii M H 2 O(g) d i M aq ii M evaporation / V Accept boiling / liquid gas M2 condensation / W Accept gas/vapour liquid / liquefaction e i M sodium ii M (squeaky) pop / explosion iii M blue / purple

6 Question 6 a M cross in box A ii M argon / Ar b i M (X) cross in box 3 Award for cross in box for X and cross M2 (Y) cross in box in box 3 for Y ii M cross in box 2 iii M green M2 yellow / orange Reject red iv M fire extinguishers / fizzy drinks c M oxidised because gain of O/oxygen/loss of electron(s) Accept increased oxidation state d i M oxygen used up/reacted/combined with magnesium Accept part of the air used up ii M 5 4 = (dm 3 ) Award 2 for correct final answer with M2 ( 5) 00 = 20 (%) working Award for correct final answer with no working

7 SECTION B Question 7 a M ºC Units required M (atm(ospheres)) Units not required M3 iron / Fe (catalyst) Ignore iron oxide Ignore oxidation states b M condensation / liquefaction / gas liquid c i M NH 3 + HNO 3 NH 4 NO 3 Reactants = 2 Products = Award if both reactant and product formulae correct but unbalanced ii M fertiliser / explosives

8 Question 8 a M copper less reactive than iron / iron more reactive than copper Do not accept iron(ii) in place of iron or copper(ii) in place of copper Accept negative (copper is not more reactive than iron) Accept iron is a better oxidising agent than copper / copper ions are a better reducing agent that iron ions. b M Copper((II)) / Cu 2+ /Cu(H 2 O) 2+ 6 / hexa aqua copper(ii) c M copper / Cu d M iron is formed/ iron displaced by zinc e M zinc / Zn f M green precipitate Ignore qualifiers such as dark/light/sludge Reject all other colours Accept solid / suspension M2 iron(ii) hydroxide / Fe(OH) 2 Accept ferrous hydroxide or formula of complex ion

9 Question 9 a i M contain hydrogen and carbon only Reject hydrogen or carbon molecules/ions ii M no double bond(s) / only single bonds (between carbon Accept no multiple bonds / no C=C atoms) b i M alkane ii M C n H 2n+2 Accept any other symbol in place of n n and 2n+2 must be clearly smaller than C and H. iii M Similar/same chemical properties M2 gradation in physical properties (or specified physical Any two for each 2 property such as increase in boiling point ) M3 neighbouring members (formulae) differ by CH 2 c M H H H All bonds/atoms must be shown. H C C C H H H H d i M (compounds with) same molecular formula Reject atoms/elements/ions M2 (but) different structures/structural formulae/displayed formulae ii M butane OR (2-)methylpropane M2 H H H H H H H H C C C C H H H H H H C C C H H H H C H H e M methane + oxygen carbon dioxide + water/steam Reactants = 2

10 M2 Products = If air given in place of oxygen, products mark can still be awarded Award M and M2 independently

11 Question 0 a M () H 2 Ignore state symbols M2 () hydrogen M3 (3) H 2 O + CO 2 Ignore state symbols Accept answers in either order M4 (3) water Accept answers in either order M5 (3) carbon dioxide b M effervescence / fizzing / bubbles Ignore gas formed c M white precipitate/solid/suspension M2 barium sulphate Question a i M electron transfer M2 from magnesium to fluorine M3 magnesium loses 2 electrons and (each) fluorine gains electron Ignore covalent Electron sharing = 0 M2 F ii M Mg 2+ Accept answers in either order b i M carbon / graphite / C ii M Melt / fused Ignore dissolved in water iii M (silvery liquid) lead if M and M2 wrong way round then M2 (brown gas) bromine give mark, but do not award M3 M3 (silvery liquid) or cathode AND (brown gas) + or anode PAPER TOTAL: 00 MARKS

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