Pressure Law

The Pressure Law can be clarified using the Kinetic Theory of Gases.

When gas is heated at a fixed volume, the gas molecules will move faster and with more energy.

The rate of collision of the gas molecules onto a unit area of the wall of the container will increase.

Each collision will also produce a greater force, because the change in momentum for each molecule increases when its speed is higher.

To maintain the same pressure in the container, the volume of the gas will increase so that the above effects will be balanced by the effect of an even smaller number of molecules per unit.

The Pressure Law states that:

For a fixed unit of mass and volume of a gas, the gas pressure is directly proportional to the absolute temperature of the gas.

P1/T1 = P2/T2

P1 = Initial Pressure
P2 = Final Pressure
T1 = Initial temperature in kelvin
T2 = Final temperature in Kelvin