Activity coefficients in (hydrogen chloride + holmium chloride) (aq) from T = (278.15 to 328.15) K

The results of the activity coefficients of HCl for this mixed electrolyte mixture have been interpreted in terms of the simpler Harned's equations and the ion-interaction model of Pitzer. Results show that the quadratic term is sufficient for the full range of YB (the ionic strength fraction of the salt) to 0.9 at all the ionic strengths studied. The Pitzer's mixing parameters SθH,Ho and ΨH,Ho,Cl (including higher order electrostatic effects) and θH,Ho and ΨH,Ho,Cl (excluding higher order electrostatic effects) have been determined. These values at T = 298.15 K are: SθH,Ho=0.115, ΨH,Ho,Cl = −.071; and θH,Ho = −.663, ΨH,Ho,Cl = 0.165. The parameters obtained in this study reproduce the activity coefficients of HCl in the mixtures within 0.015 over the entire range of ionic strengths and within 0.009 for I ⩾ 0.05 mol · kg−1 over the entire temperature range.