Studies in bivalent chromium salts

Summary The above estimations show that stannous chloride and uranyl acetate can be estimated with the help of chromous sulphate. In the case of tin, excess of ferric iron is added and its excess found by titration with chromous sulphate, using neutral red or phenosafranine as indicator. In the case of uranyl acetate chromous salt titration, the above two indicators work satisfactorily in the absence of excess of sulphuric acid, whereas methyl red and p-ethoxycrysodine give good end points even in the presence of excess acid. In the alternative procedure for estimation of uranium, chromous sulphate serves the purpose of a Jone's reductor.Ammonium metavanadate solution can be titrated directly against chromous sulphate. N-phenylanthranilic acid, diphenylamine, diphenylbenzidine and diphenylamine sulphonic acid serve satisfactorily as internal indicators for the VO_3– to VO²⁺ change. It has been shown that ferric and cupric salts do not interfere in the above titrations. Mixtures of vanadate and dichromate or vanadate and ceric sulphate can also be titrated in the same manner using the same indicators.Part VI: cf. Z. analyt. Chem. 162, 33 (1958).