Absolute Determination of the Electrochemical Equivalent and the Atomic Weight of Zinc I. Method, Apparatus, and Preliminary Experiments.

The use of a specially designed coulometer and a high accuracy coulometric circuit resulted in the accurate measurement of the electrochemical equivalent and atomic weight of zinc. The experimental conditions to make possible the final precise and accurate measurements were established. These include a study of mechanical losses from the anode during the electrolysis and the corrosion of zinc in various media used in the determination. The effects of both of these sources of error may be controlled. Mechanical losses are minimized when an amalgamated electrode is used; corrosion, when an amalgamated electrode is used in an air free system. An electrolyte, 25 wt. percent NHCl and 3 molal ZnCl. was used in these determinations. This report presents the account of research which was prerequisite to subsequent accurate determination of the electrochemical equivalent and the atomic weight of zinc.