Transformation of full thermodynamic values into pure gas components
Let us note the full thermodynamic values as symbols without indices, as P - pressure, E - internal energy, et al.
The radiative constant is accepted as
And radiative contribution to pressure and internal energy are
Then, pure gas thermodynamic values (denoted with index (nr) - no radiation) are calculated as
Finally, one can get pure gas adiabatic exponent in the form