$word_{count}$: 190

Henry's law governs dissolution of gases in liquids at low concentrations: $P_{gas}$ = $K_H$ * $x_{gas}$. $K_H$ (Henry's constant) has units of pressure and varies with temperature and gas-solvent pair. High $K_H$ = low solubility. $K_H$ increases with temperature — gases become less soluble when heated (dissolution is exothermic, Le Chatelier applies). Henry's law is the limiting case of Raoult's law for the solute at infinite dilution. For the solvent in dilute solutions, Raoult's law applies simultaneously. Key applications: (1) Carbonated beverages — CO2 dissolves under pressure, escapes when bottle is opened (P drops). (2) Deep-sea diving — N2 dissolves at high pressure causing narcosis; He (high $K_H$, low solubility) replaces N2 in breathing mixtures. (3) Blood oxygenation — O2 dissolves in blood proportional to alveolar O2 partial pressure. (4) Environmental — dissolved oxygen in water bodies decreases with temperature, affecting aquatic life. Steam distillation of immiscible liquids is related: each exerts its own vapour pressure independently, so $P_{total}$ = P_A_{std} + P_B_{std}.