Study of Chelate Formation of Rhodium (III) with Eriochrome Cyanine R

Abstract

The composition and stability of Rhodium-Eriochrome cyanine R (abbreviated as ECR) has been studied. The pink colored chelate has maximum wavelength at 530 nm and a composition of 1:2 (metal: chelating). The chelate is stable between pH 2 to 5. The values of Log K ( K= Stability constant ) as calculated by Dey and Coworkers, Job's method of Continuous Variation and Mole Ratio method using absorbance data are10.1, 9.9 and 10.2 respectively at pH 4 and at 25oC. The colored complex confirms to Beer's law over the rhodium concentration of 0.60 to 9.8 ppm.