question_answer

Although the dissolution of NaCl(s) in water is endothermic but it dissolves. Explain.

Answer:

                Sodium chloride is a crystalline solid. Energy is needed to separate it into ions, i.e., \[NaCl\,(s)+aq\xrightarrow{{}}N{{a}^{+}}\,(aq)+C{{l}^{-}}\,(aq)\,\,;\,\Delta H=+ve\] \[\Delta H\] is positive. But the ions formed in solution have greater randomness than in the solid state. This means that \[\Delta S\] is positive. Since the salt dissolves in water, this means that \[\Delta S>\Delta H\] and \[\Delta G=\Delta H-T\Delta S\] is negative.