Calcium chloride, CaCl₂, is an ionic solid. The values of some energy changes are shown in Table 1.1. Table 1.1 energy change | value/kJ mol⁻¹ lattice energy, ∆H°latt, CaCl₂(s) | -2237 standard enthalpy change of atomisation of calcium | +193 first ionisation energy of calcium | +590 second ionisation energy of calcium | +1150 standard enthalpy change of atomisation of chlorine | +121 first electron affinity of chlorine | -364

1. (a)Define lattice energy. [1][1]
2. (b)Use the data in Table 1.1 to calculate the standard enthalpy change of formation, ∆H°f, of calcium chloride. It may be helpful to draw an energy cycle. Show all your working. ΔH°f(CaCl₂(s)) = ...................................... kJ mol⁻¹ [2][2]
3. (c)Three possible values for the first electron affinity of bromine are shown in Table 1.2. One of them is correct. Place a tick by the correct value. Explain your choice. Table 1.2 possible values | place one tick (✓) in this column -342 kJ mol⁻¹ | -364 kJ mol⁻¹ | -386 kJ mol⁻¹ | explanation [1][1]
4. (d)The enthalpy change of hydration of the chloride ion can be calculated using the lattice energy of calcium chloride and the data shown in Table 1.3. Table 1.3 energy change | value/kJmol⁻¹ standard enthalpy change of solution of CaCl₂(s) | -83 standard enthalpy change of hydration of Ca²⁺(g) | -1650
5. (d)(i)Define the following terms. enthalpy change of solution enthalpy change of hydration [2][2]
6. (d)(ii)Calculate the standard enthalpy change of hydration of the chloride ion, Cl⁻(g). It may be helpful to draw an energy cycle. Show all your working. ∆Hyd(Cl⁻(g)) = ...................................... kJ mol⁻¹ [2][2]
7. (e)Calcium fluoride, CaF₂(s), can be synthesised directly from its elements. The value of ∆H°f(CaF₂(s)) is –1214kJmol⁻¹.
8. (e)(i)Predict the sign of the entropy change, ∆S°, for this synthesis. Explain your answer. The sign of the entropy change is .............................................................. explanation [1][1]
9. (e)(ii)Use the value of ∆H°f(CaF₂(s)) given in (e) and your answer to (e)(i) to predict how the feasibility for this synthesis will change with increasing temperature. [2][2]