Question

Lattice enthalpy of nacl is 788 kj/mol the dissolution of nacl requires 4kj/mol heat so hydration enthalpy of nacl is?

Answer 1

Answer. Hydration enthalpy of NaCl is -784kJ/mol

Explanation : The enthalpy of solution or enthalpy of dissolution is defined as change in enthalpy of the solution when one mole of solid substance is dissolved in a given solvent.

Given: $\Delta H_{solution}of NaCl=+4kJ/mol$ (according to chemistry conventions heat absorbed)

$\Delta H_{lattice} of NaC=788kJ/mol$

$\Delta H_{hydration} of NaCl=? kJ/mol$

$\Delta H_{solution} =\Delta H_{hydration} + \Delta H_{lattice}$

$4kj/mol=\Delta H_{hydration}+788kJ/mol$

$\Delta H_{hydration}=-784 kJ/mol$