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OCR A Specimen Paper 1 Q18
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![18 A student is asked to calculate G at 25 C for the combustion of butan-1-ol. The teacher provides two 16 pieces of information.The equation for the combustion of butan-1-ol. CH3(CH2)3OH(l)Standard entropies of butan-1-ol, oxygen, carbon dioxide and water. + 6O2(g)4CO2(g) + 5H2O(l) Equation 2 CH3(CH2)3OH(l) So/ J K1 mol1 228 O2(g) 205 CO2(g) 214 H2O(l) 70 The student carries out an experiment using the apparatus below and obtains the following results. The specific heat capacity of water is 4.18 J g1 K1. Specimen Mass of burner and butan-1-ol before burning / g Mass of burner and butan-1-ol after burning / g Initial temperature / C Maximum temperature reached / C 98.997 98.738 18.5 39.0OCR 2014 H432/01<br />
Use the information on the previous page to calculate G, in kJ mol1, for the combustion of 17 butan-1-ol according to Equation 2 at 25 C. Show all your working. Specimen G =kJ mol1 [7]OCR 2014 H432/01 Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/Specimen_QP_-_Paper_1_OCR_Chemistry_A_A-Level_18-0.jpg)
![H432/01 Question 18 H calculation from experiment Answer Mark Scheme June 20XX Marks Guidance q = 1004.1820.5 OR 8569 J OR 8.569 kJ (cid:57) Amount of butan-1-ol = 0.259 = 3.5103 mol (cid:57) 74 H = 2448 kJ mol1(cid:57) S calculation S = SproductsSreactants S = (4214) + (570)[(228) + (6205)] OR S = 12061458 (cid:57) S = 252 J K1 mol1 OR 0.252 kJ K1 mol1 (cid:57) G calculation G = HTS G = 2448(2980.252) (cid:57) G = 2373 (kJ mol1) (cid:57) Specimen ALLOW Calculator value for H = 2448.285714 correctly rounded to three or more significant figures Mark for use of correct expression with S in kJ K1 mol1 ALLOW three or more sig figs for G Total 12 P M T<br />](https://learnah.org/wp-content/uploads/2018/08/Specimen_MS_-_Paper_1_OCR_Chemistry_A_A-Level_18.jpg)