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Why if the dissolution of sodium chloride in water is endothermic, is the reaction spontaneous?

Answer 1

The dissolution of sodium chloride in water is SLIGHTLY endothermic.

But the fundamental driving for the spontaneity of chemical change is not #DeltaH#, #"enthalpy change"#, but #DeltaS#, #"entropy change."# Certainly, when #"sodium chloride"# reacts with water to form the aquated #"sodium"# and #"chloride ions"#, the entropy INCREASES.........

#NaCl(s) + "excess " H_2O rightleftharpoons Na^+ + Cl^(-)#

#Delta_"rxn"# is positive............and thus the reaction is spontaneous.

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Answer 2

Owen Ambrose

The dissolution of sodium chloride in water is spontaneous despite being endothermic because it is accompanied by an increase in entropy, which drives the reaction forward. Additionally, the strong ion-dipole interactions between the ions and water molecules help to overcome the endothermic nature of the process.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.