Formation of a solution from two components can be considered as:...

So the enthalpy of solution can either be endothermic, exothermic or neither $(\Delta$ Hsolution $=0)$, depending on how much heat is required or release in each step. If $\Delta Hsolution$= 0 , then the solution is called an ideal solution and if $\Delta Hsolution >0 or$\Delta Hsolution$< 0$, then these solutions are called non-ideal solutions. Related Theory The enthalpy of solution depends on the strengths of intermolecular forces of the solute and solvent. If the solution is ideal, and $\Delta \mathrm{H} solution$=0$, then$$\begin{aligned} & \Delta H_{\text{solution }}=\Delta H_1+\Delta H_2+\Delta H_3=0 \\ & \Delta H_1+\Delta H_2=-\Delta H_3 \end{aligned}$$