Determination of transference numbers with ion-selective electrodes. Transference numbers and activity coefficients of concentrated aqueous solutions of potassium fluoride

An experimental method has been developed to determine transference numbers by simultaneous emf measurements of cells with liquid junction using cation- and anion-responsive electrodes. As a corrolary of the transference measurements, activity coefficient data have been obtained. The method is illustrated by reporting transference and activity coefficient data of aueous KF solutions at 25°C from about 0.05 to 3 m obtained with potassium selective glass electrodes and fluoride selective solid state electrodes. The activity coefficients are in good agreement with literature data, which reflects the excellent Nernstian response of these electrodes in solutions up to 3m. The transference numbers show the typical behavior expected for a non-associated 1:1 electrolyte.