An Electrochemical Puzzle: The Catalyzed Anodic Dissolution of I-coated Palladium in Halide-Free Acid Solutions

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 3 Issue 5 (1998), S1430-4171(98)05250-9

An Electrochemical Puzzle: The Catalyzed Anodic Dissolution of I-coated Palladium in Halide-Free Acid Solutions

Jason Mallia, Stephen V. Straub, and John R. McBride*

Hofstra University, Hempstead, NY 11549-1350

Published online: 1 October 1998

Abstract. Iodine adsorbed on a Pd electrode has been shown to catalyze the anodic dissolution of Pd in halide-free acidic solutions. An undergraduate instrumental analysis laboratory experiment has been developed that enables students to use basic electrochemical techniques (cyclic voltammetry and chronocoulometry) to detect and confirm this phenomenon. Cyclic voltammograms of clean Pd and I- coated Pd were done in 0.5 M sulfuric acid solutions containing iodide and iodine as well as halide free 0.5 M sulfuric acid. The large currents noted in the halide-free solution indicate an anodic process that is not related to the oxidation process in solutions containing iodine species. Chronocoulometry was used to determine the total charge that was passed in the 0.5 M sulfuric acid solutions for clean and I- coated Pd electrodes. The results of these experiments point to a unique catalyzed corrosion process for this otherwise inert metal.

Key Words: Laboratories and Demonstrations; electrochemistry; corrosion; dissolution; palladium; catalysis; cyclic voltammetry; chronocoulometry

(*) Corresponding author. (E-mail: wolfy2@erols.com )

Article in PDF format (162 KB )

Supporting Materials:

Student handout (75 KB) 10.1007/s00897980250