Gay-Lussac's Law

Gay-Lussac's Law says that if a gas is trapped in a rigid container so its volume cannot change, raising its absolute temperature makes the pressure rise in the same ratio. This happens because hotter gas particles move faster, so they collide with the container walls more often and with greater force. The law uses Kelvin temperature, not Celsius, because pressure is directly proportional to absolute thermal energy.

Use this law for gases in sealed, rigid containers such as pressure tanks, aerosol cans, or closed metal vessels when the volume stays fixed. It is also useful in chemistry and physics problems where temperature and pressure are compared for the same gas sample.

• Using Celsius instead of Kelvin for temperature
• Using the law when the volume is not constant
• Mixing up which values are initial and final when solving for the unknown