(a(i))[2]
Define what is meant by electron affinity.
(a(ii))[2]
Define what is meant by lattice energy.
(b)[4]
Use the data below together with any relevant values from the Data Booklet to calculate the enthalpy change of formation of zinc bromide, $\text{ZnBr}_2(s)$. A suitable energy cycle may be useful. Given data: Electron affinity of $\text{Br}(g)$ = $-325\ \text{kJ mol}^{-1}$ Enthalpy change of atomisation of $\text{Zn}(s)$ = $+131\ \text{kJ mol}^{-1}$ Enthalpy change of vaporisation of $\text{Br}_2(l)$ = $+31\ \text{kJ mol}^{-1}$ Lattice energy of $\text{ZnBr}_2(s)$ = $-2678\ \text{kJ mol}^{-1}$
(c(i))[1]
Explain why the lattice energies of $\text{ZnBr}_2$ and $\text{ZnCl}_2$ are different.
(c(ii))[1]
Explain why the lattice energies of $\text{ZnCl}_2$ and $\text{ZnO}$ are different.