Table 4.1 gives the enthalpy changes of hydration, ∆Hhyd, of three ions, F⁻, K⁺ and Ca²⁺. Table 4.1 ion ∆Hhyd / kJ mol⁻¹ F⁻ -506 K⁺ -322 Ca²⁺ -1650

1. (a)(i)Define enthalpy change of hydration.[1]
2. (a)(ii)Explain the relative magnitudes of the enthalpy changes of hydration of K⁺ and Ca²⁺.[2]
3. (a)(iii)Define lattice energy.[1]
4. (a)(iv)The lattice energy, ∆Hlatt, of calcium fluoride, CaF2, is –2602 kJ mol⁻¹. Calculate the enthalpy change of solution, ∆Hsol, in kJ mol⁻¹, of CaF2. ∆Hsol of CaF2 = ......................................................kJ mol⁻¹[2]
5. (b)The formation of CaF2 at 298 K is shown. Ca(s) + F2(g) → CaF2(s) ∆H° = –1214 kJ mol⁻¹ ∆G° = –1162 kJ mol⁻¹ Calculate the entropy change, ∆S°, in JK⁻¹ mol⁻¹, for this reaction. ∆S° = ................................................................JK⁻¹mol⁻¹[2]