Calculate a lattice energy for CaH2(s) in kilojoules per mole using the following information: 

(a) Eea for H(g) = -72.8kj/mol. 

(b) Ei1 for Ca(g) = +589.8kJ/mol. 

(c) Ei2 for Ca(g) = +1154kJ/mol. Heat of sublimation for Ca(s) = +178.2kJ/mol. Bond dissociation energy for H2(g) = +435.9kJ/mol. Net energy change for the formation of CaH2(s) from the elements = -186.2kJ/mol.