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Edexcel Jun 2017 (IAL) Paper 4 Q16
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![Section B Question Number 16(a)(i) Mark (1) Correct Answer Grind the reactant(s) together (using a pestle and mortar) OR Use powdered reactants OR Stir/mix (the reactants together) OR Add a few drops of water ALLOW dampen with water IGNORE Increase surface area Make solid particles smaller Add a catalyst Reject Heating/ raising temperature Change in pressure Addition of product Removal of reactants Dissolve Question Number 16(a)(ii) Moist/damp red litmus turns blue Correct Answer ALLOW moist/damp universal indicator paper turns blue ALLOW UI for universal indicator OR (Glass rod dipped in) concentrated HCl gives white smoke / (dense) white fumes ALLOW (Pass gas into) HCl gas/fumes IGNORE (white) solid / ammonium chloride / NH4Cl Reject Mark (1) Steamy /misty fumes/ ppt<br />
Question Number 16(b)(i) Correct Answer +202.9 + 2 x 192.3 = +587.5 [(99.7 + 2 x 94.6) (= 288.9)] = +298.6 J K-1 mol-1 Correct answer with no working 3 Reject Mark (3) M1 All correct values from Data booklet (1) M2 Both multiples (1) M3 Correct numerical answer with sign and units (1) No multiples gives +200.9 1 x 192.3 gives +106.3 1 x 94.6 gives +393.2 TE at each stage IGNORE SF Use of enthalpies of formation and other strange calculations using standard entropies of elements enables M2 and M3. Reject Mark 1 mole of gas forms (1) Question Number 16(b)(ii) Sign is positive as expected, as solids Correct Answer react to form a gas (and solid) ALLOW Yes because a gas is formed TE if b(i) is negative, then allow not as expected with same reason IGNORE Disorder increases<br />
Question Number 16(c)(i) M1 So Correct Answer total = So system + So surroundings Reject Mark (3) system surroundings total So surroundings = So surroundings =Ho So = 227.5298.6 = 71.1 (J K1 mol1) (1) So T Ho = T So =(71.1 x 298) = +21187.8/21200 J mol1/+21.2 kJ mol1 M2 Final value (1) M3 Final sign and unit (1) Fully correct answer with no working 3 Accept all SF except one ALLOW TE from b(i) and internal errors 200.9 gives (+)26.6 gives -7.2968 etc 106.3 gives (+)121.1 gives -36.1176 etc 393.2 gives 165.7 gives + 49.768 etc Using Ho = T So Gives Ho = 67.795 kJ mol1 scores (1) total Question Number 16(c)(ii) Reject Mark (1) Correct Answer The temperature would fall and as the reaction is endothermic/energy absorbed from surroundings / Ho is positive ALLOW TE from sign of c(i) (Total for Question 16 = 10 marks)<br />](https://learnah.org/wp-content/uploads/2018/08/June_2017_IAL_MS_-_Unit_4_Edexcel_Chemistry_A-level_16-0-1.jpg)
