Experimental Investigation of co-ion Interactions on Measured Activity Coefficient of Ca2+ Using Ion Selective Electrode

This study aims to investigate to measuring activity coefficient of individual ion that this method was established by Khoshkbarchi and Vera. Although many studies over past 20 years have been conducted about evaluation and prediction of activity coefficient of individual ions; but, no serious attempt has been made to determine rule of interaction between ions of the same sign in activity of a particular ion in a mixture of electrolytes. Hence, we devised an experiment to explore interaction between Ca2+-K+ and K+- Na+ in CaCl2-KCl and KCl-NaCl electrolyte solutions, respectively. In this respect, potentiometry approach was employed to evaluate activity of Ca2+ in CaCl2-KCl electrolyte solution using ion selective electrode. In addition, in the case of KCl-NaCl, data have been already reported. Henderson’s equation was used to estimate junction potential created at the tip of the reference electrode. The present data was correlated by Khoshkbarchi and Vera s model and leads to disclosing its ability in prediction of ionic activities affected by co-ions interactions.