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

1 Answer
anor277
Feb 15, 2016

Because the dissolution of sodium chloride is ONLY slightly endothermic.

Explanation:

#NaCl(s) + excess H_2O rarr Na^(+)(aq) + Cl^(-)(aq)#

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 (#NaOH#) or strongly endothermic (#NH_4Cl)#.

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