Lithium iodide has a lattice energy of - 7.3*102kJ/mol and a heat of hydration of - 793kJ/mol. Find the heat of solution for lithium iodide. Determine how much heat is evolved or absorbed when 10.0g of lithium iodide completely dissolves in water.

Delta H of solution = - Lattice Energy + Hydration

Delta H of solution = - (-730) + (-793)

Delta H of solution = - 63kJ/mol

Now we find moles of LiI:

10gLiI/133.85g=.075moles

multiply moles to the delta H of solution to cross cancel moles ...75moles x - 64kJ/mol = 4.7