Ideal Gas Equation
The first video details the intuition behind the ideal gas equation PV = nRT. The other videos show you how to work out the number of moles of a gas using the ideal gas equation, work out the volume of an ideal gas at standard temperature and pressure (STP), work out the mass of oxygen and work out the molar mass of a mystery molecule at STP.

For more information on atoms, moles and equations visit Revision Science.