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Edexcel Jan 2013 Paper 4 Q15
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![Mark Mark Section B Question Number 15(a) Acceptable Answers Reject carbonyl/carboxylate (It has) three (moles of) COOH groups / three (moles of) carboxylic acid groups / three (moles of) protons /three (moles of) H+ /it is tribasic / three acid groups/ three (moles of) replaceable hydrogens/triprotic ALLOW Three acid groups Reject Incorrect units (no 2nd mark) Acceptable Answers system =)[200.5 + (3 x 213.6) + (3 Question Number 15(b)(i) FIRST, CHECK THE FINAL ANSWER IF answer = +546 (J mol1 K1) award 2 marks 546 (J mol1 K1) scores (1) as sign omitted)(S x 69.9)][199.9 + (3 x 101.7)] (1) = [+1051][+ 505] = +546 (J mol1 K1) (1) Allow + 0.546 kJ mol1 K1 2nd mark is CQ on entropy values used for example EITHER Omission of factor of x3 for some or all substances in the equation OR The use of one incorrect entropy value(s) from the data book OR One missing value Note If two or more of the above three errors are made together, (0) awarded. IGNORE sf except 1 sf<br />
Mark Mark Acceptable Answers Reject Just more product / more particles formed 2 substances going to 3 substances First mark Gas formed (from solid) OR Liquid formed (from solid) OR Gas and liquid formed (from solid) (1) Second mark EITHER More moles of product than reactants / more moles formed OR 4 mol (of reactants) to 7 mol (of products) OR 4 molecules to 7 molecules NOTE: If specific numbers are stated, these must be correct (ie 47) OR Increase in disorder / increase in ways of arranging particles (1) IGNORE entropy increases NOTE: Both points may be made in the same sentence Acceptable Answers Reject surroundings =) H OR 70000(S T 298 (1) = 234.8993289 = 235 J mol1 K1 (1) OR(S T 298 surroundings =) H OR 70 (1) =0.235 kJ mol1 K1 (1) IGNORE sf except 1 sf NOTE: Correct units are required for the award of the second mark +235 with units scores (1) Incorrect rounding (e.g. 234 / 234.89) no 2nd mark +235 with no units (0) overall Question Number 15(b)(ii) Question Number 15(b)(iii)<br />
Question Number15(b)(iv) (S Acceptable Answerstotal = Ssystem + S surroundings) = (+546) + (235) = (+)311 (J mol-1 K1) OR = (+)0.311 kJ mol-1 K1 CQ on (i) and (iii) IGNORE sf except 1 sf Question Number 15(b)(v) Acceptable Answers Positive so feasible / spontaneous / will occur / reaction goes / reacts (at 298 K) NOTE: LOOK BACK at answer to (b)(iv) IF answer to (b)(iv) has a positive sign (the + sign can be stated or implied) THEN ALLOW JUST feasible / spontaneous / will occur / reaction goes / reacts (at 298 K) Mark CQ on sign of answer to (iv) Reject Incorrect units Reject Mark Mark (Total 9 marks)<br />](https://learnah.org/wp-content/uploads/2018/08/January_2013_MS_-_Unit_4_Edexcel_Chemistry_A-level_15-0.jpg)
