A m m mol -n s -1 pre-exponential factor (unit varies) b j , b a.u. bias (vector notation in bold) c i , c mol m -2 /mol m -2 concentration E A kJ mol - For simulation of industrially relevant chemical processes, source terms of species are critical since they set apart reaction processes from thermal or mechanical separation processes. Generally, the source term for species i , ṡi , in mol m -2 can be written in accordance to their stoichiometric coefficients, ν i,j , and the rate of reaction j, r j , as eq. .