Which law states that the amount of any given gas that will dissolve in a liquid at a given temperature is directly proportional to the partial pressure of that gas?

• A. Charles' Law
• B. Dalton's Law
• C. Henry's Law
• D. Gay-Lussac's Law

Answer: (C)

Gas solubility in a liquid at a constant temperature scales with the pressure of the gas above the liquid. This relationship is Henry's Law: the amount of dissolved gas is directly proportional to its partial pressure, with a proportionality constant that depends on the specific gas, the solvent, and the temperature. In practical terms, increasing the partial pressure of the gas pushes more of it into solution, and lowering the pressure releases it back out. This explains why carbonated beverages stay fizzy under pressure and why gas exchange in diving or respiration depends on partial pressures of different gases. The equation C = k_H × P_gas captures this idea. Other gas laws describe different relationships—such as how volume relates to temperature at constant pressure, or how total pressure is the sum of individual gas pressures, or how pressure changes with temperature at constant volume—which are not about solubility of a gas in a liquid.