Lattice energy and Born-Haber cyclesEdexcel A-Level Chemistry: Mind map

Exam questions on Lattice energy and Born-Haber cycles

1. A student is studying the formation of sodium chloride, NaCl, from its elements using a Born–Haber cycle, which is an application of Hess's law.
   Define the enthalpy change of atomisation of chlorine and write an equation, with state symbols, to represent it.2 marks
2. A student is constructing a Born–Haber cycle for sodium chloride with these data: standard enthalpy change of formation of NaCl(s) = −411 kJ mol⁻¹; enthalpy change of atomisation of sodium = +107 kJ mol⁻¹; enthalpy change of atomisation of chlorine, ½Cl₂(g) → Cl(g) = +122 kJ mol⁻¹; first ionisation energy of sodium = +496 kJ mol⁻¹; first electron affinity of chlorine = −349 kJ mol⁻¹.
   Write an equation, with state symbols, for the lattice energy of sodium chloride and explain why this enthalpy change is exothermic.2 marks
3. A student is using a Born–Haber cycle to find the lattice energy of magnesium chloride, MgCl₂. The data are: standard enthalpy change of formation of MgCl₂(s) = −641 kJ mol⁻¹; enthalpy change of atomisation of magnesium = +148 kJ mol⁻¹; first ionisation energy of magnesium = +738 kJ mol⁻¹; second ionisation energy of magnesium = +1451 kJ mol⁻¹; enthalpy change of atomisation of chlorine, ½Cl₂(g) → Cl(g) = +122 kJ mol⁻¹; first electron affinity of chlorine = −349 kJ mol⁻¹.
   Calculate the lattice energy of magnesium chloride.3 marks