Now You See It—Now You Don’t

Surprise your students with this demonstration of an oscillating chemical reaction that changes color in a rhythmic fashion. Addition of three white solids to a colorless solution results in a color change to orange. In less than one minute, the solution reverts back to its original colorless state. The color of the solution continues to oscillate every 30 seconds between colorless and orange for another 30 minutes. Abstract principles—the nature of a reaction mechanism and the existence of intermediates along a reaction pathway—come to life in this engaging demonstration.