The Ideal Gas Law is a combination of Boyle's Law, Charles' Law and Avogadro's Law. It can be expressed by a single equation, PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the general gas constant, and T is the absolute temperature.
The value of the gas constant, R is 8.3143 J K-1 mol-1. Note that these are SI units, and therefore the volume used in this equation must be in m3and the pressure in N-2. In all gas law calculations, absolute values of temperature (Kelvin) must be used.
Another commonly encountered value for R is 0.08205 atm dm3 K-1 mol-1. If this value is used then the volume must be in dm3 and the pressure in atm.
See also Boyle's Law | Charles' Law | Ideal Gas | Avogadro's Law.