The ideal gas constant is also known as the molar gas constant, the gas constant or the universal gas constant. This constant is written as [math]R[/math], and is a constant of proportionality (constant number that is multiplied on one side of a proportional relationship to make them equal) for the ideal gas law.[1] The ideal gas law is simply [math]PV=nRT[/math] where [math]P[/math] is pressure, [math]V[/math] is volume, [math]n[/math] is the number of moles of gas, and [math]R[/math] is the ideal gas constant.[2]

This constant of proportionality depends on which units are used for the other variables in the ideal gas law equation. Some common values for [math]R[/math] are:

This constant is closely related to Boltzmann's constant, [math]k_B[/math] (to get the ideal gas constant from Boltzmann's constant, multiply by Avogadro's number: [math]R=N_A k_B [/math]).

Further Reading