The boiling point of a substance X at 1 atm pressure is 500 K. the enthalpy of vapourisation at the boiling point of X (l) is 80 kJ / mol. The molar specific heat of X(l) = 5 × 10-3 mol and Cp of X(g) = 5 × 10-4 kJ/mol.. What is the molar latent heat of vaporization of X(l) at 800 K and at 1 atm?