A general form of systems of differential equations for chemical equilibrium shifts within a monophase with arbitrary numbers of components and reversible chemical reactions was obtained for ideally and nonideally ("quasi-regularly") associated solutions. Such systems of equations can conveniently be used for simulation purposes; that is, for calculating the true detailed compositions and thermodynamic potentials of phases and their derivatives (the chemical potentials of components and compounds, true entropies and volumes, isobaric heat capacities, etc.). When such systems are applied to the model of nonideally associated solutions, mathematically solving the problem of bringing nonideality parameters to self-consistency is not necessary, because we always obtain thermodynamically consistent results; that is, the obtained set of the thermodynamic functions of the phase satisfies the Gibbs - Duhem equation, cross-differentiation relations, chemical equilibrium conditions with respect to reversible formation or decomposition of compounds within the phase, etc.