A general systematic approach including ionic strength
effects
is proposed for the numerical calculation of concentrations of chemical
species in multiequilibrium problems. This approach extends the versatility
of the approach presented in a previous article and is applied using
the Solver option of the Excel spreadsheet to solve real problems
such as the calculation of the pH of buffer solutions at any ionic
strength. It is useful for undergraduate programs, in post-graduate
programs, and in professional laboratories to predict experimental
conditions.