Bimetallic Electrode Systems in Electrometric Analysis. I. Systems Comprising Two Dissimilar Metals

Abstract

or as a weak electrolyte. It seems probable, however, that even the pure hydride if it could be obtained in the molten state would prove t o be an excellent conductor of electricity. Summary X new method was worked out for the preparation of pure sodium and potassium hydrides. They were obtained in the form of beautiful white, needle-like crystals. Potassium hydride decomposes with explosive violence in moist air. Calcium hydride was prepared free from metallic calcium. The eutectic mixture of potassium and lithium chlorides was found to be a solvent for hydrides. X solution of calcium hydride in this eutectic mixture was electrolyzed, and hydrogen was given off a t the anode in the quantity required by Faraday's law. 'l'he writer wishes to acknowledge his appreciation of the many helpful suggestions of members of the Faculty a t the University of California where this investigation was made, and to thank Professor G. N. Lewis especially, a t whose suggestion and under whose direction this research was prosecuted. No gas was liberated a t the cathode.

Relations between Voltammetry and Potentiometric and Amperometric Titrations

“…SINCE 1951, when the author presented the essentials in this paper in a seminar, various classes of titration methods have been studied systematically in this country and abroad. Reilley, Cooke, and Furman (9,15) were the first to discuss the relation between voltammetry and potentiometric titrations at constant current at two identical indicator electrodes, a type of titration introduced by Willard and Fenwick (18) in 1922. Gauguin, Chariot, and their coworkers (1)(2)(3)10) in Paris and Duyckaerts (7) in Liége have contributed by studying the relations between current and potential in partially reversible systems.…”

“…The first metal couple used in this method is palladium-platinum in the titration of ferrous iron with dichromate by Hostetter and Roberts (11). Willard and Fenwick (18) and Van Name and Fenwick (17) made an extensive study of the use of various attackable electrodes in oxidation-reducton titrations. The tungsten-platinum couple was found particularly useful.…”

“…Two (Identical) Indicator Electrodes. The method was introduced by Willard and Fenwick (18), who passed a small, but constant, current through the system. In a most instructive paper Van Name and Fenwick (17) gave the values of the potentials of the cathode and of the anode separately during the titration of various oxidation-reduction systems.…”

Differential Electrolytic Potentiometry Determination of Nanogram Quantities of Halides at Extreme Dilution by Constant Current Coulometry.

“…The titration signal is in the form of a peak, the first differential of the zero-current potentiometric curve, for reversible reactions, and is Z shaped for irreversible reactions (1,6). The antecedents (29,31,38) of the method and its relationships with other polarization techniques (18,19,21,32,33) have been examined (1,3,11) and the theoretical interpretation is in course of publication (34)(35)(36)(37).…”

Square Wave Titrimetry

“…Two methods of electrometric end point detection are fundamentally based upon the measurement of the slope of the current-voltage curve in the zero current region. The first method, introduced by Willard and Fenwick (47) and modified and extended by several recent workers (3, 7, 13-15, 40) involves potentiometry at constant current. The other method, commonly called the "dead stop" titration after Foulk and Bawden (11), involves the measurement of current passing between two indicator electrodes at a small constant applied potential and dates back to Salomon (1$).…”