- The pressure exerted by a given mass of gas, when the volume is constant, is directly proportional to its temperature.
- This law is named after French physical chemist Joseph Louis Gay-Lussac, although he cited earlier unpublished work by Jacques Charles, who determined Charles Law independently.
- It states that the pressure of a given amount of gas in a rigid container is directly proportional to its Kelvin temperature. Increasing the temperature of a gas gives it more kinetic energy, which causes the molecules to move faster and impact the walls of the container more often, thus resulting in higher pressure. Conversely, cooling a gas decreases its kinetic energy, and the molecules impact the walls of the container less often, leading to lower pressure.
Gay-Lussac's Law is used to predict the behavior of gases, such as how they expand or contract depending on their temperature. It is often used along with Boyle's Law and Avogadro's Law to form the Ideal Gas Law, which explains how ideal gases behave in real life.
To see an example of the gas laws in action, consider a deodorant can with a pressure gauge. As the can is heated, the air inside of it rises and the pressure increases. If the can is then cooled, the pressure decreases. This is because as the temperature of the gas decreases, its kinetic energy decreases, and its molecules move more slowly. This results in less impact of the molecules on the wall of the can, and thus, less pressure.