Avogadro's law

Avogadro's law, discovered by Amedeo Avogadro, dictates that the number of molecules in a specific volume of gas is dependent on its pressure and temperature.

The law has three facets:

• The amount of moles is directly proportional to the gas' volume
• The amount of moles is proportional to its pressure
• The amount of moles is inversely proportional to its temperature

Multiply all that by a constant to make an equality instead of a proportion and you get:

n = PV/RT

Where R is equal to 8.31 (kPa * L)/(K * mol), and n represents one mole.

One mole occupies approximately 22.4 Liters at STP.