<P> Where Φ is an undetermined constant, which may be taken from the Sackur--Tetrode equation for an ideal gas to be: </P> <Dl> <Dd> Φ = T 3 / 2 Λ 3 = (h 2 π m k) 3 (\ displaystyle \ Phi = T ^ (3 / 2) \ Lambda ^ (3) = \ left ((\ frac (h) (\ sqrt (2 \ pi mk))) \ right) ^ (3)) </Dd> </Dl> <Dd> Φ = T 3 / 2 Λ 3 = (h 2 π m k) 3 (\ displaystyle \ Phi = T ^ (3 / 2) \ Lambda ^ (3) = \ left ((\ frac (h) (\ sqrt (2 \ pi mk))) \ right) ^ (3)) </Dd> <P> This equation expresses A in terms of its natural variables V and T, and therefore gives us all thermodynamic information about the system . The mechanical equation of state was already derived above </P>

Van der waals constants in terms of critical properties