Boyle's law

For a fixed mass of gas at constant temperature, the volume is inversely proportional to the pressure.

Mathematically, Boyle's law can be stated as

or

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

The equation states that product of pressure and volume is a constant for a given mass of confined gas as long as the temperature is constant. The law can be usefully expressed as