Which law states that the total pressure exerted by a mixture of gases is equal to the sum of the pressures of each gas, with each gas acting as if it alone occupied the total volume?

• A. Charles' Law
• B. Dalton's Law
• C. Henry's Law
• D. Avogadro's Law

Answer: (B)

When gases share a container, each gas would exert the same pressure it would if it were alone in that container, at the same temperature. The total pressure is simply the sum of those individual pressures, so Ptotal = P1 + P2 + P3, and so on. This describes Dalton's Law of Partial Pressures, which holds best for ideal gases.

In practice, gases behave this way when they don’t interact strongly and are not at extreme pressures or temperatures. The others describe different relationships: Charles' Law connects volume to temperature at constant pressure; Henry's Law deals with how much gas dissolves in a liquid at a given pressure; Avogadro's Law relates volume to the number of particles at fixed temperature and pressure.