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Edexcel Jun 2014 Paper 1 Q20
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![Section B Question Number 20 (a)(i) Question Number 20 (a)(ii) Acceptable Answers Reject (Compound of) carbon and hydrogen ONLY/ENTIRELY/PURELY Mixture of carbon and hydrogen only Mark Mark Reject Just different temperatures Breaking of hydrocarbon chains Mark 6CH0101 1406 Reject Acceptable Answers (Contains) only (CC) single bonds/ onlybond(s) OR (Contains) no (C=C) double bond(s)/no triple bond(s) OR Cannot undergo addition (reactions) ALLOW Has maximum number of hydrogen atoms / has maximum amount of hydrogen /can form no more bonds IGNORE references to alkanes Question Number 20 (b)(i) Boiling point(s) / boiling Acceptable Answers temperatures / boiling ranges ALLOW Different sizes of molecules / different chain lengths / different numbers of carbon atoms IGNORE References to melting points / melting temperatures / condensing<br />
Acceptable Answers Save fossil fuels / saves finite resources / saves petrol / saves diesel OR More sustainable OR Uses renewable resources / biodiesel made from natural resources OR Biodiesel is a renewable fuel OR Plants (more) carbon neutral / use of plants improves carbon footprint (of fuel) OR Biodiesel has smaller carbon footprint / zero carbon footprint OR Biodiesel (more) carbon neutral ALLOW Reverse argument for petrol / normal diesel (eg crude oil is non-renewable) IGNORE Less impact on the environment / references to environmentally friendly / less polluting / acid rain IGNORE References to global warming or Greenhouse Effect or climate change. Question Number 20 (b)(ii) Reject Mark 6CH0101 1406<br />
Question Number 20 (c)(i) C9H20 Acceptable Answers IGNORE Any structures drawn out Acceptable Answers Question Number 20 (c)(ii) First mark: Any ONE of:- (Greater) demand for smaller molecules / (Greater) demand for smaller alkanes / (Greater) demand for alkenes / To make more useful products / To make more reactive product / To make smaller molecules / To make shorter molecules / To make alkenes / To make shorter chains NOTE: ALLOW To produce fuel(s) Marks are stand-alone (1) Second mark: (High temperatures needed to) break (the C-C and / or C-H) bonds OR To break (down) the (hydrocarbon) chain(s) / To break (down) the molecule(s) / To split the molecule(s) / To break the hydrocarbon OR (Reaction is) endothermic ALLOW To overcome the (high) activation energy / the reaction has a high activation energy / provide activation energy IGNORE C-C bond is stable References to increasing rate (of reaction) References to yield / equilibrium References to efficiency / producing less CO (1) Mark Mark Reject Reject No 2nd mark if any of the following are mentioned: Separation of molecules Breaking intermolecular forces References to (high) boiling temperatures / (high) boiling points References to (high) melting temperatures / (high) melting points 6CH0101 1406<br />
Question Number 20 (d)(i) (Substance that) produces energy or Acceptable Answers produces heat IGNORE:- References to power References to just exothermic References to burning or combustion or heating the fuel or reference to oxygen Acceptable Answers C4H10(g) + 6O2(g)4CO2(g) + 5H2O(l) OR C4H10(g) + 6.5O2(g)4CO2(g) + 5H2O(l) OR C4H10(g) + 13 O2(g)4CO2(g) + 5H2O(l) 2 OR 2C4H10(g) + 13 O2(g)8CO2(g) + 10H2O(l) OR Any other correct multiples Correct species (1) Balancing and state symbols correct (1) 2nd mark is dependent on the 1st mark Question Number 20 (d)(ii) Reject Reject H2O(g) C4H10(l) Mark Mark 6CH0101 1406<br />
Acceptable Answers Question Number 20(d)(iii) C4H10 + 4O24CO + 5H2O Reject Mark OR C4H10 + 4.5 O24CO + 5H2O OR C4H10 + 9 O24CO + 5H2O 2 OR 2C4H10 + 9 O28CO + 10H2O OR Any other correct multiples IGNORE State symbols even if incorrect Question Number 20(d)(iv) Mark Acceptable Answers Reject no air / no oxygen Limited (supply of) air / oxygen OR insufficient (supply of) air / oxygen OR Oxygen / air not in excess OR Not enough air / not enough oxygen ALLOW Lack of oxygen / lack of ventilation IGNORE It is not completely oxidized 6CH0101 1406<br />
Mark Question Number 20(e)(i) Acceptable Answers Reject First mark Calculation of the sum of the Mr values of all the products = 217.8 If using Br = 80, Mr = 218 (1) Second mark Calculation of % atom economy using value of total Mr [ = 136.9 (x 100%) ] 217.8 = 62.856 (%) (1) NOTE If using Br = 80, final answer = 62.844 (%) ALLOW ECF for the 2nd mark on an incorrect total Mr value IGNORE sf except 1 sf Correct answer with no working (2) Check rounding of answer NOTE If one error only is made, (1) mark awarded For Mr = 217.8, 62.8% (no 2nd mark, as this is a rounding error) 6CH0101 1406<br />
Acceptable Answers Question Number *20(e)(ii) First mark: Mark Reject H (the fourth and fifth marks cannot be awarded if H appears in either propagation step) Initiation (step) (1) Second mark: BrBrBr + Br / Br22Br (1) Third mark: Propagation (steps) (1) Fourth and fifth marks: Br + C4H10C4H9 + HBr (1) Br2 + C4H9C4H9Br + Br (1) Allow in either order Sixth mark: Termination (step(s) (1) Seventh mark: Any one of Br + BrBr2 OR C4H9 + BrC4H9Br OR C4H9 + C4H9C8H18 (1) (Total for Question 20 = 21 marks) 6CH0101 1406<br />](https://learnah.org/wp-content/uploads/2018/08/June_2014_MS_-_Unit_1_Edexcel_Chemistry_A-level_20-0.jpg)
