Chelatometric Titration of Bismuth with Gallein Indicator

Abstract

A method using gallein as indicator for the direct titration of bismuth with disodium salt of EDTA was devised. The titration was carried out in nitric acid. The optimum pH for the titration was found to be at pH. 1.3 to 2.3. The sharpest end point occurred at around pH 1.7. The end point was reached when the magenta color gave place to a pale yellow. The interference of approximately equimolar concentration of various foreign ions was studied. By the proposed method bismuth can be accurately titrated in the presence of a variety of both cations and anions including large amounts of lead ions.