the same molecular-kinetic picture of a single component gas can also be applied to a gaseous mixture. for instance, in the chapman-enskog approach the viscosity formula_94 of a binary mixture of gases can be written in terms of the individual component viscosities formula_95, their respective volume fractions, and the intermolecular interactions. as for the single-component gas, the dependence of formula_94 on the parameters of the intermolecular interactions enters through various collisional integrals which may not be expressible in terms of elementary functions. to obtain usable expressions for formula_94 which reasonably match experimental data, the collisional integrals typically must be evaluated using some combination of analytic calculation and empirical fitting. an example of such a procedure is the sutherland approach for the single-component gas, discussed above.