Gay-Lussac’s Law


Propane tanks are extensively used with grills of barbecue. But you’ll not love that in the middle of your grilling, you run out of gas. You can purchase the gauge which measures the pressure in the tank to notice how much is left.

The gauge measures the pressure and will record a high pressure on hot days comparative to colder days. So, you have to keep the temperature of the air in mind before deciding to refill the tank prior to your next cook-out or not.


Gay-Lussac’s Law

When the temperature of the gas sample is increased in a rigorous container, the gas pressure also increases. With the increase in kinetic energy, it will result in a molecule of the gas banging more force on the walls of the container, which in turn results in more pressure.

In between 1778 – 1850, Joseph Gay-Lussac, the French chemist discovered the relationship between the pressure present in gas and its absolute temperature.

In Gay-Lussac’s Law, it has been stated that the pressure of a specified mass of gas changes directly with the absolute temperature of the gas on the condition when the volume is kept constant. Also, Gay-Lussac’s law is defined as Pressure Law.

Gay-Lussac is occasionally credited for being the first to describe Dalton’s state, which means that the total pressure of the gas is the total of the partial pressure of gases individually.

Gay-Lussac’s Law is very much identical to Charles’s Law, except the type of container used in both gas laws. While the container in the experiment of Charles’s Law is known to be flexible, it is known to be rigid in the experiment of Gay-Lussac’s Law.

Likewise identical to Charles’s law, Gay-Lussac’s Law is mathematically represented as:

P/T = P1/T1 = P2/T2, or

P1T2 = P2T1


The graph of Absolute temperature Vs Pressure also describes the direct relationship between both. As the gas is cooled down at constant volume, its pressure constantly goes down, until the gas is converted into liquid form by condensation.

The gas’ pressure of constant volume and mass is directly proportional to the absolute temperature of the gas

P α T, or

P/T = K


P = pressure of the gas

T = temperature of the gas (in kelvins)

K = constant

This law is right holds exactly true for the above discussion regarding the kinetic energy!


Real life examples on Gay Lussac’s Law:

A wide range of application in our day-to-day life is based on Gay Lussac’s law. Some of its examples are:

  • Firing bullet – Here, the combustion or ignition of gunpowder gives rise to superheated gas as a result of which the pressure increases and with that, the bullet covers a longer distance with higher speed.
  • The burning of automobile tire: When the rubber of automobiles is burnt, then it will result as air pressure increases in the tire because of the increased temperature. This might result in a tire wall explosion.
  • Heating closed aerosol: When there’s burning of aerosol cans like deodorants, and spray paint, the temperature increased can increase pressure, which might result in an explosion of the container. This is the reason why there’s a warning on almost every deodorant bottles that ‘do not put empty bottles in the fire’.
  • Heat food in the oven: When the food is put in a microwave oven to heat, the air within the oven gets heated and therefore is pressurized.


Please Share