11177 [Turn over 9 Which reaction has an increase in entropy? A N2(g)  +  3H2(g)  "  2NH3(g) B 4NH3(g)  +  5O2(g)  "  4NO(g)  +  6H2O(g) C 2NO(g)  +  O2(g)  "  2NO2(g) D 4NO2(g)  +  O2(g)  +  2H2O(g)  "  4HNO3(l) 10 Propanone reacts with iodine as follows: CH3COCH3(aq)  +  l2(aq)  "  CH3COCH2l(aq)  +  HI(aq) Which statement is correct? A The brown colour fades B The pH increases C The purple colour fades D This is not a redox reaction 11177 Section B Answer all six questions in this section 11 Barium chloride is formed from its elements as follows: Ba(s)  +  Cl2(g)  "  BaCl2(s)  -855 kJ mol-1 The following enthalpy changes can be used to calculate the lattice enthalpy of barium chloride: I Ba(s)  "  Ba(g) +175 kJ mol−1 II Ba(g)  "  Ba2+(g)  +  2e− +1500 kJ mol−1 III Cl2(g)  "  2Cl(g) +242 kJ mol−1 IV Cl(g)  +  e−  "  Cl−(g) −364 kJ mol−1 (a) What name is given to each of the enthalpy changes I–IV? I II III IV [4] (b) Explain what is meant by the term lattice enthalpy. [2] 11177 [Turn over (c) Calculate, to four significant figures, the lattice enthalpy of barium chloride. [2] (d) What name is given to the cycle used to calculate lattice enthalpy? [1] (e) Given Ba2+(g)  "  Ba2+(aq) −1309 kJ mol−1 Cl-(g)  "  Cl-(aq) −378 kJ mol−1 calculate, to an appropriate number of significant figures, the enthalpy of solution of barium chloride and use it to explain why barium chloride is soluble in water. [3]