If you are using the finite-rate model with reversible reactions (see Section 14.1.1), you will need to define the standard state entropy, for each species . These inputs are used to define the mixture entropy as
where is the reference temperature at which is defined. Standard state entropies are input in units of J/kgmol-K in SI units or in units of Btu/lb mol- R in British units.
For each species involved in the reaction (i.e., each fluid material contained in the mixture material), you can set the Standard State Entropy and Reference Temperature in the Materials panel.