Use of a Commercial Silver-Silver Chloride Electrode for the Measurement of Cell Potentials to Determine Mean Ionic Activity Coefficients

In this work, we describe the modification of the setup for a classic electrochemistry experiment in the physical chemistry laboratory, in which a commercial silver-silver chloride electrode was successfully substituted for an “in-house” fabricated one. A correction was made to the Nernst equation for the cell by accounting for the concentrated potassium chloride solution present in the electrode. A plot of the corrected cell potential versus concentration was used to more accurately determine the standard potential for the silver-silver chloride electrode. From an extrapolation to zero concentration, a value of 0.216 ± 0.002 V was calculated. This value was subsequently utilized to calculate the mean ionic activity coefficients that are in better agreement with the trend predicted using Debye-Hückel theory.