Hydrogen and Palladium Foil: Two Classroom Demonstrations

In these two classroom demonstrations, students observe the reaction between H 2 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, PdH 0.7 . In the process, palladium undergoes a noticeable color change and increase in brittleness. In the second classroom demonstration, the kinetics of H 2 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 H 2 mass transport. Both classroom demonstrations use the same simple apparatus, but otherwise are mutually independent.