## Chemistry: The Molecular Science (5th Edition)

$\Delta_{r}H_{solution}=-lattice\,energy+ total\, enthalpy\,of\, hydration\,of\,ions$ $=-(-2258\,kJ/mol)+(-2175\,kJ/mol)$ $=83\,kJ/mol$ As $\Delta_{r}H$ is greater than 0, this is an endothermic process (heat absorbing process).