Q.Using Henry's law and the fact that dissolution of a gas in a liquid is an exothermic process, explain why the solubility of a gas in a liquid decreases as the temperature of the liquid is raised, and why this matters for aquatic life in warm water.

[!TLDR] Dissolving a gas is exothermic, so by Le Chatelier's principle raising the temperature shifts the dissolution equilibrium back towards undissolved gas, which appears in Henry's law as $K_H$ rising with temperature. [!ANSWER] Gas solubility falls as temperature rises be …

Dissolving a gas in a liquid is normally an exothermic process, since the gas molecules lose translational freedom and become solvated by the liquid, releasing energy. By Le Chatelier's principle, raising the temperature of the system shifts this dissolution equilibrium backward, favouring the undissolved gas over the dissolved state, so less gas remains dissolved at higher temperature for the same partial pressure — in Henry's law terms, $K_H$ increases with temperature, so a larger pressure is now needed to dissolve the same mole fraction. This is directly important for aquatic life: warmer water holds less dissolved oxygen, and fish and other aquatic organisms in warm or thermally-polluted water can suffer oxygen st …

Identify gas dissolution as exothermic, then apply Le Chatelier's principle to tem …

Do not confuse this with the increase in solubility with pressure (a separate, correct trend) — temperature and pressur …