An Easy Process to Prepare a Copper(I)/Copper Sulfide Electrode and Its Behavior in Alkalimetric Titrations

Abstract

A copper sulfate (Cu₂S) film is formed on the surface of a copper wire by immersion in melted (>55°C) sodium thiosulfate, Na₂S₂O₃·5H₂O. This Cu₂S/Cu electrode is sensitive to sulfide ions and can be used in potentiometric titration of Na₂S solutions with copper(II) cations. Besides, as a novelty, it gives a good response to H⁺ cations at a wide pH range, even in alkaline medium, as checked in potentiometric titration of acetic and phosphoric acids. An analysis of a number of potentiometric measurements leads to interpretation of the electrode response in acidic/basic medium.