Complexation and precipitation equilibria in the system NiII–CrVI–H2O
Abstract
A potentiometric and spectrophotometric study of the complexation equilibria between CrVII and NiII has been performed. Formation of the soluble NiCrO4 complex has been found and the thermodynamic formation constant has been calculated (log β°11= 2.40 ± 0.03), as well as its molar absorptivity values at the different wavelengths studied. The precipitation equilibria in the system NiII–CrVI–H2O have also been investigated. A mixed precipitate, NiCrO4· 3Ni(OH)2, has been found and its thermodynamic solubility constant has been determined (log K°so=–51.1 ± 0.2).