Reductimetric Determination of Copper(II) With Iron(II) in Phosphoric Acid Medium And in Presence of Bromide Ion

Abstract

A simple, convenient and accurate reductimetric titration method has been developed for the determination of copper(II )(in the range 10-30 mg) with iron(II) in phosphoric acid medium (ca. 7 M) and in presence of bromide ion (ca. 2.0 M). The end point can be detected either potentiometriclly (accuracy ± 0.4 %) or using cacotheline as a redox indicator (accuracy ± 0.6 %). The precision of the method is determined by computing the pooled standard deviation and 95 % confidence limits. The method has been extended to the determination of copper content in a sample of brass and copper-nickel alloy. The formal redox potentials of the oxidant [Cu(II)/Cu(I)] and reductant [Fe(III)/Fe(II)] systems in the optimum titration conditions and the transition potential of the indicator have been measured and explained the conditions needed in the titration as well as the effect of bromide ion. The interference due to diverse ions has been studied and the advantages of the present method over the existing ones have been discussed.