Values of the universal constant of gases

PV = nRT

R = PV/nT

SI system

Nm^{3N
m}J
R = ------ ------- = ------ = ------- = 8.314 J K^-1 m^-1
m²K moleK moleK mole

The value reported above can be calculated by remembering that at standard conditions, i.e., 1 atm (1.0132 10⁵ N/m²) and 0 °C (273.15 K) the volume occupied by one mole of a gas is 22.414 liters (0.022 m³).

The same can be done by using differents units for P, V and n, thus obtaining:

J K^-1 Kg-mole^-1 = 8314

kJ K^-1 Kg-mole^-1 = 8.314

cal K^-1 mole^-1 = 1.987

cal K^-1 Kg-mole^-1 = 1987

cm³ atm K^-1 mole^-1 = 82.058

L atm K^-1 mole^-1 = 0.0820578

L Torr K^-1 mole^-1 = 62.364

L bar K^-1 mole^-1 = 0.0831451

J K^-1 Kg-mole^-1 = 8314	kJ K^-1 Kg-mole^-1 = 8.314
cal K^-1 mole^-1 = 1.987	cal K^-1 Kg-mole^-1 = 1987
cm³ atm K^-1 mole^-1 = 82.058	L atm K^-1 mole^-1 = 0.0820578
L Torr K^-1 mole^-1 = 62.364	L bar K^-1 mole^-1 = 0.0831451