Gas Laws

Gay-lussac's Law: Formula, Statement and Discoverer

Gay-Lussac's law: formula, statement and discoverer

Gay-Lussac's law is one of the gas laws that relates the pressure of a gas to temperature at constant volume. In its statement, this law states that the volume of a quantity of gas increases or decreases proportionally to its temperature if the volume remains constant (isochoric process).

The Gay-Lussac's law formula that relates the pressure and temperature of a gas is:

P / T = ct.


  • P is the pressure.

  • T is the absolute temperature.

  • ct is a constant value.

As you can see, if the temperature decreases, the gas pressure increases.

A practical example of the Gas-Laussac law is what happens in a pressure cooker: the volume remains constant but the pressure increases with increasing temperature. For this reason, these pots are so reinforced.

Other notable gas laws are Boyle Mariotte's law, Charles's law, and the ideal gas law.

Who Was the Discoverer of the Gay-lussac's Law?

Before the formulation of this law it was discovered by Guillaume Amontons and Jacques Charles. The Italian physicist Alessandro Volta also conducted similar investigations in 1791 on the expansion of gases.

The law takes its name from the French physicist-chemist Joseph Louis Gay-Lussac because he was the one who formulated and announced it in 1802. 

Sometimes the name Gay-Lussac is also used to refer to Charles's law that relates the volume and temperature of a gas at constant pressure. In reality, Louis Joseph Gay-Lussac announced Charles's law in 1802, while Jacques Charles had discovered it 15 years earlier, in 1787.

Charles's law states that the volume of a gas is directly proportional to its absolute temperature if the pressure is kept constant.

Why Does This Relationship Occur?

This relationship is explained by the fact that as the gas temperature increases, its molecules move faster, which implies an increase in kinetic energy. As the speed of these particles increases, the number of collisions with the walls of the container increases. As the temperature drops, the molecules slow down, reducing the collisions with the walls.

How Did Gay-lussac Discover This Law?

To verify this relationship, Gay-Lussac put gas in a closed container. He then placed a heat source under the container, heated the gas, and saw the pressure against the walls of the container increase.

When he removed the heat source, the pressure exerted by the gas on the container walls began to drop until it reached its initial state.


Published: December 8, 2021
Last review: December 8, 2021