[tqnguy9230]

Calculate a lattice energy for CaH2 (in kilojoules per mole) using the following information:
Eea for H = -72.8 kJ/mol
Ei1 for Ca = +589.8 kJ/mol
Ei2 for Ca = +1145 kJ/mol
Heat of sublimation for Ca = +178.2 kJ/mol
Bond dissociation energy for H2 = +435.9 kJ/mol
Net energy change for the formation of CaH2 from its elements = -186.2 kJ/mol

I need an explanation of this problem. Not just the answer. I'm totally lost.

[Schrödinger]

How do you get to CaH2 from the corresponding elements Ca and H in their natural states? There are many steps invloved, as the data suggests. Write down those steps (not necessarily in order).