A new method for the pH calculation of solutions and mixtures of acids,bases and salts

The improved successive approximation method calculates the exact [H⁺] and pH value of solutions and mixtures of acids, bases and salts, and can be applied to titration data. The procedure consists in the calculation of the concentration of all species present in solution, selection of the appropriate rule of electroneutrality and introduction of suitable correction factors in order to obtain a final quadratic equation which is easily solved. Compared with existing methods of pH calculation, which are based on the Newton-Raphson iteration procedure, the proposed method requires a smaller number of iterations and a shorter calculation time. As there are no limitations on the number of compounds, nor on the number or values of acidity and basicity constants, nor on the concentration range, complex problems can be solved and titration curves plotted in a short time.