Coulometric and amperometric studies

• Main Author: Rowley, John Keith
• Format: Others
• Published: 1954
• Online Access: https://thesis.library.caltech.edu/4854/1/Rowley_jk_1954.pdf; Rowley, John Keith (1954) Coulometric and amperometric studies. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/X71A-V450. https://resolver.caltech.edu/CaltechETD:etd-12082003-113012 <https://resolver.caltech.edu/CaltechETD:etd-12082003-113012>

The coulometric titration of thiosulfate with iodine has been investigated at different hydrogen ion concentrations. The applicability of this titration to the determination of oxidizing agents has been demonstrated by determining microgram quantities of ferric iron, chromate, and selenious acid. A modification of the Norris and Fay method for the volumetric determination of selenious acid has been compared to a proven, but less direct method. It has been shown that tripositive antimony can be titrated in concentrated hydrochloric acid solutions more successfully with chlorine than with bromine. Evidence concerning the nature of the species of tripositive and pentapositive antimony existing hydrochloric acid solutions has been obtained amperometrically during the coulometric titrations in hydrochloric acid of tripositive antimony with bromine and chlorine, and of pentapositive antimony with cuprous copper. The indicator currents obtained with an amperometric system during the reduction of iodate with cuprous copper and during the oxidation of iodide with both chlorine and ceric cerium have been investigated as functions of the hydrogen ion concentration, the chloride concentration, and the applied potential. A quantitative study of the amperometric system used for above measurements has been made. An equation has been derived which relates the indicator current to the applied potential and to the concentrations of electrode-reactive species in the solution. Experimental tests have been made on the ferrocyanide-ferricyanide half-cell. The amperometric end point is discussed.