# Why does the temperature of solution change marginally upon addition of sodium chloride to water?

$N a C l \left(s\right) + e x c e s s {H}_{2} O \rightarrow N {a}^{+} \left(a q\right) + C {l}^{-} \left(a q\right)$
This reaction is very slightly endothermic. The energy required to breakup the ionic lattice is ALMOST balanced by the formation of ion-dipole bonds between the ion and the solvent water molecules. For other salts, for instance sodium hydroxide, or ammonium chloride, dissolution in water is strongly exothermic ($N a O H$) or strongly endothermic (NH_4Cl).