Potentials of Cells with Liquid-Liquid Junctions

摘要

The potentials of cells have been measured. The results are roughly in agreement with the demands of the Henderson equation for liquid junction potentials but disagree with the results of previous investigators wherever potassium chloride was one of the electrolytes employed. The disagreement is attributed to experimental error in previous determinations. A reexamination of the theoretical foundations of the Henderson equation shows that it is more properly regarded as relating to the potentials of whole cells containing the liquid junction in question. A similar remark applies to the Lewis and Sargent equation. In connection with another investigation it became necessary to measure the e.m.f. of a number of cells. The work was in part a repetition of previous measurements of MacInnes and Yeh but disagreed with their results by more than the admitted experimental error wherever potassium chloride was one of the electrolytes employed. It had already been noted by the earlier authors that their results with potassium chloride appeared anomalous, but they were unable to verify the natural suspicion that their potassium chloride electrode was in error. The results of the present work show beyond reasonable doubt that such must have been the case, however.