Calculation of Diffusion Coefficients in Ternary Systems from Diaphragm Cell Experiments

Using a generalized least square procedure, a method is developed to estimate diffusion coefficients, D , from concentration measurements made in a set of experiments of varying duration but with the same initial conditions. The method requires neither approximations nor restrictions in the flow equations. The D and their errors are calculated simultaneously with the adjustment of the weighted observables - concentrations of the two solute components and time. A procedure is described to insure convergence in a given experimental set. The effect of the duration of the longest experiment, and errors in the observables on the estimated values of D and their errors, are investigated. Application of the method to available data yielded values for D in agreement with those previously calculated by more involved procedures.