Accession Number : AD0709275

Title :   VOLUME CHANGES IN ELECTROLYTIC HYDROGEN EVOLUTION AT MERCURY IN AQUEOUS HYDROCHLORIC ACID,

Corporate Author : MEMORIAL UNIV OF NEWFOUNDIAND ST JOHN'S DEPT OF CHEMISTRY

Personal Author(s) : Smith,Frank R. ; Heintze,Hans-Ulrich

Report Date : 05 JUN 1969

Pagination or Media Count : 8

Abstract : Volume changes at a mercury cathode in hydrogen-saturated aqueous 0.1 M hydrochloric acid during electrolysis at 25C are less than those predicted by Faraday's Law, 2H(+)(aq) + 2e(-) (metal) = H2(g), over a range of current densities from 0.4 to 83 micro A/sq mm. Difficulties attributable to the anodic reaction of mercury were found using an apparatus similar to that of Muller but constructed entirely of glass. A two-compartment cell proved to be advantageous in isolating the cathode reaction. Rates of volume change attributable to formation of H2(g) almost invariably increased with time of electrolysis but were always below expectation. An increase of volume was observed after electrolysis. The evidence is consistent with formation and subsequent decomposition of a hydrogen amalgam. It suggests that, contrary to the usual assumptions, hydronium-ion discharge is not the slowest step in the overall hydrogen gas-producing reaction. (Author)

Descriptors :   (*HYDROGEN, *ELECTROLYTIC CELLS), (*MERCURY, *CATHODES(ELECTROLYTIC CELL)), ELECTROLYSIS, VOLUME, ELECTROCHEMISTRY, CANADA

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE