Spectrophotometric Study of Chelate Formation by Interaction of Hexavalent Chromium and Alizarin Red S

Formation of a pink-coloured complex by the interaction of Cr (VI) and sodium alizarin-3-sulphonate (Alizarin Red S) has been reported. The chelate has maximum absorption. at 515 m\(\mu\). The composition, as determined by the method of continued variation using spectrophotometric mesurements, is indicated to be 1:1. The chelate is stable between pH 3.5 and 8.0. The stability has been determined by a method described by the authors and the values of logK and\(\bigtriangleup\)Fowork out respectively to be 4.72 ± 0.25 and -6.52 ± 0.35 kcal. at 250.