# What are the Four Gas Laws in Chemistry?

The gas laws are often used to predict the behaviour of gaseous substances when they are placed under certain physical conditions. Examples of gas laws include Gay-Lussac’s law, Charles’ law, and Boyle’s law. The four gas laws provide relationships between the following quantities:

• The pressure exerted by a gas on the walls of its container (denoted by ‘P’)
• The absolute temperature of the gas (denoted by ‘T’ and measured on the Kelvin scale)
• The number of moles of the gas, which can be visualized as the amount of gaseous substance (denoted by ‘n’)
• The total volume that is occupied by the gaseous substance (denoted by ‘V’ and measured in litres)

## Boyle’s Law

Boyle’s law states that the pressure exerted by gaseous substances on the walls of their containers increase as the volume of their containers decrease, as long as the absolute temperature of the gas and the amount of gaseous substance are kept constant.

This law can be mathematically expressed as:
P = k/V (or) PV = k

Where P is the pressure of the gas, V is the volume of the gas, and k is a constant.

## Charles’ Law

The statement of Charles’ law can be written as – “When the amount of gaseous substance and the pressure associated with the gas is kept constant, the volume occupied by a gaseous substance is always proportional to the absolute temperature of the gas”.

The mathematical expression of Charles’ law is:

V/T = k (or)  V = kT

Where V is the volume of the gas, T is the absolute temperature associated with the gas, and k is a constant.