Hydrogen and Palladium Foil: Two Classroom Demonstrations

Abstract

In these two classroom demonstrations, students observe the reaction between H2 gas and Pd foil. In the first demonstration, hydrogen and palladium combine within one minute at 1 atm and room temperature to yield the non-stoichiometric, interstitial hydride with formula close to the maximum known value, PdH0.7. In the process, palladium undergoes a noticeable color change and increase in brittleness. In the second classroom demonstration, the kinetics of H2 uptake is determined and yields a zero-order rate law. Other observations are provided to guide students to conclude that the experimental conditions for the demonstration result in kinetics governed by H2 mass transport. Both classroom demonstrations use the same simple apparatus, but otherwise are mutually independent.