Joseph-Louis Gay-Lussac: Ideal Gas Law

Today we celebrate the contribution that French chemist and physicist Joseph-Louis Gay-Lussac made to the world of science and engineering.

Born 240 years ago in Paris, Gay-Lussac is most notably acknowledged for his definition of the ‘ideal gas law’ that looks at the thermal expansion of gasses.

Gay-Lussac studied at École Polytechnique in Paris, and then went on to work with notable scientists such as Claude-Louis Berthollet, Louis-Jacques Thenard and Jean-Baptiste Biot. 

The Ideal Gas Law

Also known as the Pressure Law, this defines the relationship between the pressure and temperature of a fixed mass of gas kept at a constant volume.


A computer animated version of the law is illustrated on the NASA website here.

Giving Credit to Charles

A previous scientist, Jacques Charles, provided the foundations for Gay-Lussac Law by defining the law of volumes, explaining that gas expands when heated. It was Gay-Lussac that further confirmed this.  

Practical Applications Using Gay-Lussac’s Law

  • Demonstrate the relationship between pressure and temperatures of a fixed volume of an ideal gas with the Ideal Gases – Gay-Lussac’s Law Experiment (TD1001).

Further Experiments for Learning the Gas Laws

  • Understand Boyle’s Law of Ideal Gasses (TD1000) that shows the relationship between pressure and volume of an ideal gas at a fixed temperature.
  • Demonstrate the behaviour and expansion of a perfect gas with the Expansion of a Perfect Gas experiment (TD1004).