New Data on Activity Coefficients of Potassium, Nitrate, and Chloride Ions in Aqueous Solutions of KNO3 and KCl by Ion Selective Electrodes

Debasmita Dash,C Mallika,U Kamachi Mudali,Shekhar Kumar

doi:10.5402/2012/730154

Abstract

Ion selective electrodes (ISEs) are used to measure the single-ion activity coefficients in aqueous solutions of KNO3 and KCl at 298.15 K against a double-junction reference electrode. The EMF responses of ISEs up to 0.01 m are plotted to obtain the slope and intercept values. The obtained slopes and intercepts are used in Nernst equation for higher concentrated solutions for calculation of individual ion activity coefficient. The mean ionic activity coefficients are estimated from single ion activity coefficient, and the obtained results are compared with the literature values.

Highlights

Activity of a species in a solution is referred to as its effective concentration in that solution
Ion selective electrodes (ISEs) have been used to measure the activity coefficients of individual ions of KNO3 from ∼0.001 m to ∼3.5 m and KCl from ∼0.001 m to ∼5 m at 298 K and atmospheric pressure
The ISEs used in this work were calibrated with the standard solution supplied along with the respective ISEs

Summary

Introduction

Activity of a species in a solution is referred to as its effective concentration in that solution. The knowledge of individual ionic activity coefficients is important for the design of equilibrium processes involving electrolyte solutions as well as for processes involving ion exchange and pollution control [1]. Single-ion activity coefficients are traditionally termed as not measurable by simple thermodynamic methods due to space charge interactions. Vera and coworkers [2,3,4,5] and few other researchers [6,7,8,9] demonstrated the application of ion selective electrode (ISE) technique for measurement of single-ion activity coefficients. Ion selective electrodes (ISEs) have been used to measure the activity coefficients of individual ions of KNO3 from ∼0.001 m to ∼3.5 m and KCl from ∼0.001 m to ∼5 m at 298 K and atmospheric pressure. The calculated mean activity coefficients from single-ion activity coefficients are compared with the literature value [9, 10]

Experimental Work

Results and Discussion

Conclusion