Mercurous salts as new reductimetric reagents for titrations in alkaline medium : Titration of chromium salts, arsenites, hydrogen peroxide and hydrazine
✍ Scribed by F. Burriel-Marti; F. Lucena-Conde; S. Arribas-Jimeno
- Publisher
- Elsevier Science
- Year
- 1954
- Tongue
- English
- Weight
- 483 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
BUHRIEL-MARTI, I?. L'IJCENA-CONDE AKSII, S. AIZRIBAS-J IMENO Laboraiory of Analytical Chertristry of the i~'aculty of Science. Uwivcvsily. ~rt~rf High Council of Scicnfific Resenrch, .\ladvid (Sfirri~)
In the first part of this study1 the optimum conditions were determined under which a mercurous salt quantitatively reduces the ferricyanide ion. The procedure can bc applied to the determinations by back-titration of those substances which are oxidized by the ferricyanide ion in alkaline medium, adding excess ferricyanide and titrating the latter afterwards by the methods suggested.
We carried out a titration study of chromium salts, arsenious salts, hydrogen peroxide and hydrazine. In each case, the conditions of alkalinity and temperature under which the respective substance oxidizes quantitatively with the ferricyanide were determined. Afterwards, in every case, the excess of fcrricyanide was titrated with a standard mercurous pcrchlorate solution at room temperature and adequate alkalinity. I. TITHAT1ON OP CHROMIUM SAL'I-S BOLLENBAGH AND LUCHMANN~ were the first to oxidize chromium salts in alkaline medium for analytical purposes by means of potassium fcrricyanidc. The chromate obtained was precipitated with Ba(OI-I), and then they titrated the ferricyanidc formed during the reaction by permanganimetry, in acid medium, according to HAHN'S method. Later, HAHN~ carried out a direct determination of the chromium salt with fcrricyanidc in a hot, strongly alkaline medium. However, he found that the reaction is slow and he suggests the addition of a small quantity of thallous salt to accelerate the reaction. DEL FRESNO AND VALD$S* tried a successive titration of quadrivalent vanadium and chromium sulphate in alkaline medium with potassium fcrricyanide, but did not obtain quantitative results. Ferricyanide and trivalent chromium react in basic medium according to the equation : 3[Fe(CN)Ja + CrC* + 8OH--+ 3[Fe(CN)J4 + CrO,-* + 4H20 Rcfevences p. 220.