Temperature's Influence on Solubility Equilibria

Expert reviewed • 22 November 2024 • 3 minute read

Introduction

Understanding how temperature affects solubility is crucial for predicting and controlling chemical equilibria. This article explores the relationship between temperature changes and solubility product constants ( $K_{sp}$ ) in ionic compounds.

The Temperature-Solubility Relationship

The solubility product constant ( $K_{sp}$ ) of an ionic compound varies with temperature, following principles of chemical equilibrium. This variation depends on whether the dissolution process is endothermic or exothermic.

Endothermic Dissolution

When the dissolution process absorbs heat (∆H > 0):

Increasing temperature → Higher $K_{sp}$ → Increased solubility
Decreasing temperature → Lower $K_{sp}$ → Decreased solubility

Exothermic Dissolution

When the dissolution process releases heat (∆H < 0):

Increasing temperature → Lower $K_{sp}$ → Decreased solubility
Decreasing temperature → Higher $K_{sp}$ → Increased solubility

Le Châtelier's Principle and Solubility

These temperature effects can be explained using Le Châtelier's Principle:

For endothermic reactions, adding heat (increasing temperature) shifts the equilibrium toward products, increasing solubility
For exothermic reactions, removing heat (decreasing temperature) shifts the equilibrium toward products, increasing solubility

The Common Ion Effect: Impact on Solubility Equilibria

Return to Module 5: Equilibrium and Acid Reactions