<Dl> <Dd> P = ρ R s T, (\ displaystyle P = \ rho R_ (s) T,) </Dd> </Dl> <Dd> P = ρ R s T, (\ displaystyle P = \ rho R_ (s) T,) </Dd> <P> where R s (\ displaystyle R_ (s)) is the specific gas constant for a particular gas, in units J / (kg K), and ρ = m / V is density . This notation is the "gas dynamicist's" version, which is more practical in modeling of gas flows involving acceleration without chemical reactions . </P> <P> The ideal gas law does not make an assumption about the specific heat of a gas . In the most general case, the specific heat is a function of both temperature and pressure . If the pressure - dependence is neglected (and possibly the temperature - dependence as well) in a particular application, sometimes the gas is said to be a perfect gas, although the exact assumptions may vary depending on the author and / or field of science . </P>

Who discovered that air is a mixture of gases