Statement 1: If a salt dissolves spontaneously while the solution cools down, the entropy change of the dissolution must be positive.
Statement 2: Dissolution of a salt in water is always an exothermic process.

Question

Statement 1: If a salt dissolves spontaneously while the solution cools down, the entropy change of the dissolution must be positive.

Statement 2: Dissolution of a salt in water is always an exothermic process.

TestHub · Accepted Answer

A cooling solution means ΔH sol > 0 (endothermic). For the process to be spontaneous, ΔG = ΔH - TΔS < 0, which with ΔH > 0 is possible only when ΔS > 0 (Statement 1 correct). Statement 2 is wrong on two counts: dissolution can be endothermic (as here, e.g. NH 4 NO 3 ), and it is the entropy increase, not heat release, that drives such cases. Ans: (c).

Chemistry - Thermochemistry Question with Solution | TestHub

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