The convective diffusion equations were used to obtain mean concentrations and concentration fluctuation covariances during turbulent reactive mixing of fast reversible reactions. The mean concentrations are directly applicable to reactions that are much faster than the mixing, while the covariances can serve as a first approximation closure far slower reactions. The covariances should also be useful for testing more general closure models. Numerical examples are presented for the simple mass-action rate law with stoichiometric coefficients of unity.