Ideal Gases

We know from the three gas laws that constant

Ideal gases all behave in the same way so we can assign a letter to the constant. The equation becomes:

If the volume and temperature of a gas are kept constant then the pressure depends on R and the number of particles in the container. We must take account of this by bringing the number of moles, n, into the equation:

R is the Molar Gas Constant, R = 8.31 J K^-1 mol^-1

This is called the equation of state for an ideal gas. The concept of ideal gases is used to approximate the behaviour of real gases. Real gases can become liquids at low temperatures and high pressures.

Using the Avogadro’s equation for n we can derive a new equation for an ideal gas: