According to Amagat's Law, the volume of a gas mixture is the sum of what?

• A. the volumes of the pure components measured at the same temperature and pressure.
• B. the partial pressures of each component.
• C. the temperatures of each component.
• D. the masses of each component.

Answer: (A)

Amagat's law treats volumes as additive for a gas mixture. At a given temperature and pressure, the mixture’s total volume equals the sum of the volumes each pure component would occupy if it were present alone under the same conditions. This means you add the pure-component volumes measured at the same T and P to get the mixture volume. For ideal gases, since each component has the same molar volume RT/P at those conditions, the mixture volume simplifies to RT/P times the total number of moles, aligning with the idea of additive volumes. The concept differs from adding partial pressures or temperatures or masses, which do not directly give the mixture’s volume under Amagat’s framework.