The energy released when Na+(g) and Cl- (g) form NaCl(s) is 778. kJ/mol. Approximately 162. J is absorbed from the surroundings when 2.35 g of NaCl is completely dissolved in water. What is the enthalpy of hydration of NaCl?

-777.838

Explanation:

Given data,

Lattice energy (energy released to form NaCl )= 778 kJ/mol

Heat of solution = 162 Joules

                                 = 0.162 kJ (converted to kilojoules)

Substitute the values in the given formula,

Enthalpy of hydration = ΔHsolution – ΔHlattice energy

                            = 0.162 – 778

Therefore, Enthalpy of hydration = -777.838

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )