Acceptable Answers Reject Mark. CaO(s) + CO 2 (g) First mark: All three formulae in box, ignoring state symbols (even if incorrect)

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Carol Gordon
6 years ago
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1 (a)(i) CaCO + 2HCl CaCl 2 + H 2 O + CO 2 ALLOW multiples No other species to be allowed IGNE state symbols even if incorrect H 2 CO instead of H 2 O + CO 2 on right hand side of equation (a)(ii) H reaction ( CaCO (s) CaO(s) + CO 2 (g) ) (2HCl) H H 2 (2HCl) CaCl 2 (aq) + H 2 O(l) + CO 2 (g) Mark each point independently First mark: All three formulae in box, ignoring state symbols (even if incorrect) This mark is stand alone, NOT to be marked CQ on answer to (a)(i) Second mark: Two arrows, BOTH pointing downwards Any other formulae Third mark: Left hand arrow labelled as H AND right hand arrow labelled H 2 (whatever the direction of the arrows) (a)(iii) ( H reaction ) = H H 2 This is a stand alone answer NOT to be marked CQ on (a)(ii) and/or (a)(i) Any other expression

2 (b) Any two from: Heat /energy loss Heat /energy loss to surroundings Heat /energy loss to apparatus Measured under non-standard conditions Incomplete reaction Incomplete combustion Inaccuracy of equipment/apparatus Human error CO 2 escapes 2 Specific heat capacity of solutions is approximate Density of solution assumed to be g cm /same as (pure) water Bond enthalpies Impurity of reactants Transfer losses Side-reactions Large relative error in temperature measurement

3 2 (a) (i) (q = 250 x (.5 2.0) x 4.8 =) (J) 0000 (J) IGNE sf except sf IGNE units even if incorrect IGNE any sign at this stage ALLOW 0.97 (kj) 2 (a) (ii) (M r ethanol) = 46 (Mass ethanol burned = =) 0.74 (g) ALLOW as alternative to 0.74 (Amount of ethanol = =) 0.06 (mol) 0.02 (mol) ethanol NOTE: Moles of ethanol are CQ on molar mass and /or mass of ethanol burned IGNE sf except sf NOTE: Correct answer with no working /limited working scores () Mark the three points independently 2 (a) (iii) Answer (i) (000 x answer (ii)) 2 NOTE: Be aware of numbers held in calculator not corresponding to what is written in answer Value and negative sign IGNE sf except sf NOTE: Answer consistent with (a)(i) and (a)(ii) with no working scores E.g ( ) = 682 (kj mol ) ALLOW Just kj as the units NOTE: If correct answer is given in J mol, the units of J mol must be clearly given for the second mark to be awarded. Correct answer in J instead of J mol

4 2 (b) (i) 00 x (70 Answer to (iii)) 70 = value e.g. 00 x (70 682) 70 = 50.2 % Incorrect rounding of final answer (0) 2 (b) (ii) Any three from: Heat loss (from the beaker)/beaker not insulated/heat loss as no lid on beaker (containing the water) /no stirring Incomplete combustion (of the alcohol)/formation of soot (on beaker) Not all of the energy from the flame is used to heat the beaker and/or the water More accurate thermometer Just experimental /human error Experiment carried out at a different (laboratory) temperature Too large a distance between flame and beaker / no draught excluder Heat capacity of the beaker is neglected/beaker absorbs heat/glass absorbs heat Evaporation of the (hot) alcohol Evaporation of the (hot) water

5 2 (b) (iii) 2 C(s) + H 2 (g) + ½ O 2 (g) C 2 H 5 OH(l) 2CO 2 + H 2 O H f = 2 x ( 94) + x ( 286) ( 70) = 276 (kj mol ) Correct expression or cycle Evidence for both doubling H θ c [C] and trebling H θ c [H 2 ] Correct sign and answer Correct answer with no working scores Correct answer with an incorrect cycle () () IGNE units even if incorrect Alternatively the following answers score as shown even with incorrect cycle or incorrect units NOTE: (+)276 with or without working scores (+)690 with or without working scores 690 with or without working scores 552 with or without working scores 4 with or without working scores (+)4 with or without working scores (+)0 with or without working scores REMINDER IF ANY OTHER ANSWER IS GIVEN: ALL WKING MUST BE CHECKED TO SEE IF ANY MARKS CAN BE AWARDED

Mark Scheme (Results) January 2011

Mark Scheme (Results) January 2011 Scheme (Results) January 2011 GE GE hemistry (601/01) Edexcel Limited. Registered in England and Wales No. 4496750 Registered Office: One90 igh olborn, London W1V 7B Edexcel is one of the leading examining