Question

Draw the Born Haber cycle for CaS( 1Mole Calcium Sulphide) inserting the appropriate energy, states of the substances and the energy values as well as their respective energy changes

Answer 1

In this diagram,

$\Delta H_f$ is the enthalpy change of formation of CaS(s),

$\Delta H_{at}$ is the enthalpy change of atomisation of Ca(s) to Ca(g), 178 kJ/mol and of S(s) to S(g), 279 kJ/mol,

$\Delta H_1$ and $\Delta H_2$ are the enthalpies of ionisation of Ca,

$\Delta H_{1a}$ and $\Delta H_{2a}$ are the enthalpy changes of electron capture ionisation (electron affinity with a negative sign) and

$\Delta H_{LE}$ is the lattice energy of CaS.

All quantities are given in kJ/mol.