An-Najah Staff

The kinetics of cyanide abstraction from potassium hexacyanoferrate (II) by mercuric chloride in the presence of the ligand Ferene S in aqueous solutions have been investigated spectrophotometrically by measuring the change in the absorbance of the blue Ferene-ferrous complex at 593 nm. The reaction rate between potassium hexacyanoferrate (II) and Ferene is dramatically a slow process, while in presence of a trace amount of mercury (II) the reaction tends to completion within few minutes. Effect of pH, temperature, hexacyanoferrate (ll), Ferene S, and mercury(II) concentrations on the rate of the reaction have been investigated. The order ofthe reaction has been found to- be first order with respect to potassium hexacyanoferrate (ll), Ferene S, and mercury (II) chloride. Activation parameters for both the catalysed and the uncatalysed reactions have been calculated. A proposed mechanism that could explain the results has been suggested. A kinetic method for mercury determination in medicinal samples has been proposed.