According to Henry's Law, the amount of gas dissolved in a liquid is proportional to what?

• A. The square root of the partial pressure
• B. Its inverse with respect to partial pressure
• C. The partial pressure of the gas
• D. Independent of partial pressure

Answer: (C)

Henry's law says that, at a fixed temperature, the amount of a gas dissolved in a liquid is directly proportional to the gas’s partial pressure above the liquid. In formula form, dissolved concentration equals a constant (specific to the gas–liquid pair and temperature) times the partial pressure. This means doubling the partial pressure increases the dissolved amount in the liquid in a linear fashion, up to the point where deviations from ideal behavior or saturation occur. Temperature matters because the proportionality constant changes with temperature, so solubility typically decreases for gases when temperature rises. The key idea is a direct, linear relationship with partial pressure, not a square-root or inverse relation, and not independent of pressure.