The gas laws were developed during the ned of 18^{th} century when scientists realized that this is possible to calculate the relationships between volume, pressure, and temperature of a sample gas and it could be used ahead to calculate the approximation of all gases.

Gases usually behave differently in different situations because gases contain molecule that are spaced widely and the equation of an ideal gas is derived from the kinetic theory. However, earlier gases are taken as a special case of the ideal gas equation where one or more variables are kept constant.

One special case here is Gay-Lussac’s law that determines the relationship between pressure or temperature of a gas. Based on this law, the volume is kept constant, and pressure of an ideal gas is directly proportional to the temperature. Here is how Gay-Lussac’s law can be given –

\[\ \frac{P1}{T1} = \frac{P2}{T2} \]

Where, P1 and P2 are the initial pressure or final pressure of gas. Both can be expressed in terms of atm units. T1 refers to the initial temperature and T2 is taken as the final temperature that is expressed in Kelvin.

Take an example where volume is kept constant in case of the closed container. In case, pressure of the container increases, the temperature would also increase significantly. The above graph is given for the ideal gases and it is linear in nature. With the Gay-Lussac’s law, we find the relationship between the temperature or pressure of a gas. At the fixed volume, temperature and pressure will become proportional to each other and as soon as temperature goes down then pressure will also decrease in the same ratio.