Gas laws
The
gas laws include
Boyle's Law,
Charles' Law and
Graham's Law and describe the relationship between
temperature,
pressure and
volume of gases. They are collectively generalized by the
universal gas equation, also known as the
ideal gas law.
A gas which obeys gas laws exactly is hypothetical, and is known as an ideal gas (or perfect gas).
Boyle's Law, named after Robert Boyle, states that the volume occupied by a gas at constant temperature is inversely proportional to the pressure applied. In other words,

Charles Law, named after
Jacques Charles, states that the pressure that a gas exerts on the walls of its container is determined by the
momentum of the
atoms and
molecules of the gas, which in turn is determined by the temperature. As the temperature increases the atoms and molecules move faster, and so exert a greater pressure on the walls. If the walls are rigid, such that the volume of the container is held constant, then the relationship between pressure P and temperature T is given by Charles' Law:

Graham's Law, named after
Thomas Graham, states that the
kinetic energy of two samples of different gases at the same temperature is identical.