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CIE Nov 2015 v3 Paper 4 Q1
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![Section A Answer all the questions in the spaces provided. PMT (a) The dissolving of an ionic compound in water is accompanied by an energy change, the enthalpy change of solution, H sol. MgCl 2(s) + aqMg2+(aq) + 2Cl (aq) Describe, in terms of bond breaking and bond making, what happens to the solid ionic lattice when an ionic compound dissolves in water.[2] (b) (i) What is meant by the term enthalpy change of solution, H sol?[1] (ii) Use the following data to calculate the standard enthalpy change of hydration, chloride ions, Cl (g). You may find it helpful to construct an energy cycle. , of enthalpy change (Mg2+(g)) lattice energy of MgCl 2(s) enthalpy change of solution for MgCl 2(s) value 1925 kJ mol1 2524 kJ mol1 155 kJ mol1UCLES 2015 9701/43/O/N/15 (Cl (g)) =kJ mol1 [2]<br />
PMT (iii) The enthalpy change of hydration for Na+, (Na+(g)), is 410 kJ mol1. Suggest an explanation for why the of the Mg2+ ion. of the Na+ ion is less exothermic than the[2] (c) Describe and explain how the solubility of the Group II sulfates varies down the group.[4] [Total: 11]UCLES 2015 9701/43/O/N/15 [Turn over<br />](https://learnah.org/wp-content/uploads/2018/08/November_2015_v3_QP_-_Paper_4_CIE_Chemistry_A-level_1-0.jpg)
![Page 2 Mark Scheme Syllabus Paper Cambridge International A LevelOctober/November 2015 9701 43 Question Marking Point Marks Total Marks PMT (a) ionic bonds break / bonds between Mg 2+ and Cl - break forces / bonds / attractions form between the ions and water (b) (i) (the energy change) when 1 mole of a substance dissolves in water / becomes aq (ii) 2+ H latt MgCl 2 + H sol MgCl 2 = H hyd Mg + 2H lhyd Cl 2524155 = 1925 + 2H = 377 kJ mol 1 hyd Cl (iii) magnesium / Mg is higher charge / sodium / Na is smaller charge magnesium / Mg is smaller / sodium / Na is larger Mg stronger attraction for water / Na weaker attraction for water any two (c)solubility decreases lattice energy and hydration enthalpy decreasehydration enthalpy decreases more rapidly / is dominant factorso (enthalpy change of) solution becomes less exothermic / more endothermic (a) Co 3s 3p 3d 4s 3+ Co 3s 3p 3d (b) (i) atom or ion, bonded to (one or more), ligands (ii) any two from: two (or more) oxidation states, catalytic activity, coloured ions or compoundsCambridge International Examinations 2015 [Total: 11] [1] [1]<br />](https://learnah.org/wp-content/uploads/2018/08/November_2015_v3_MS_-_Paper_4_CIE_Chemistry_A-level_1.jpg)