6. (a) (i) Draw a fully-labelled Born–Haber cycle forthe formation of solid barium chloride, BaCl2, from its elements.Include state symbols for all species involved.
(ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1
(ii) Use your Born–Haber cycle and the standardenthalpy data given below to calculate a value for the electron affinity ofchlorine. Enthalpy of atomisation of barium +180 kJ mol–1
Enthalpy of atomisation of chlorine +122kJ mol–1
Enthalpy of formation of barium chloride –859kJ mol–1
First ionisation enthalpy of barium +503kJ mol–1
Second ionisation enthalpy of barium +965kJ mol–1
Lattice formation enthalpy of barium chloride –2056kJ mol–1
Ive had a go at this Q and know the answer to it - it came up as -347kj/mol which was half the value initially got of -695 - so i missed the step to half that value but i dont understand why i need to half it?