The Potentiometric Determination of Arsenates¹

Abstract

The Potentiometric Determination of Arsenates 577 water and alcohol. The velocities increase in the orders given.2. The decompositions in water, and the decomposition of the sodium salt in alcohol, follow the first order law, but the decompositions of the anilinium salt in aniline and alcohol, and of the barium salt in alcohol, show an increase in the specific reaction rate as the decomposition proceeds. These departures have been explained on the basis of changes in the degree of ionization.3. The reaction velocity has been shown to be dependent upon the concentration of the trichloroacetate ion. It is suggested that the reaction is a unimolecular decomposition of the trichloroacetate ion.4. Temperature coefficients for the decomposition in the several solvents support the hypothesis that the stability of the ion is determined by the extent of solvation and the nature of the solvating substance.5. The formation of chloride ion in solutions of trichloroacetates in water and alcohol has been shown to be the result of an oxidation of the chloroform which results from the decomposition of the trichloroacetates.Madison, Wis.

Potentiometric Titrations. A Review with Bibliography

“…Spychalski(543) titrated Bredig solution for silver with bromide or iodide with an accuracy of 0.5 to 1 per cent of the silver present.Hiltner and Gittel (234) developed a systematic potentiometric scheme for estimation of silver, bismuth, lead, copper, and cadmium in the same solution.Silver nitrate as reagent. Arsenate, in acetate buffer plus alcohol(Hanson et al,221; Spacu,537) Azide (Moskovich, 386; lead azide in 2 per cent barium nitrate solution, 0.04 N in nitric acid, and buffered with 0.2 N…”