Apparent molar ionic products of water in aqueous potassium nitrate solutions and calibration of the glass electrode as a wide-range proton concentration probe

Abstract

Precise values of the apparent molar ionic (stoicheiometric) products of water in KNO₃ solutions have been determined in the temperature range 15–45 °C and over a range of ionic strengths 0·060–0·180M by means of a glass, silver–silver chloride electrode system calibrated as a proton concentration probe. The results are extrapolated to infinite dilution and compared with values previously reported in aqueous KCl solutions. The accuracy and precision of the results were found to be limited by the reproducibility of the Beckman ‘Research’ meter used confirming that, properly calibrated, such electrode systems can replace the hydrogen electrode without undue loss of accuracy. Proton dissociation constants for the 2-hydroxyethylammonium ion are also reported for 0·060M-KNO₃ solutions and the use of this reagent as a calibrant in glass-electrode work is suggested.