Another Twist of the Foam: An Effective Test Considering a Quantitative Approach to "elephant's Toothpaste"

Abstract

In this work, a new quantitative look at the well-known "Elephant´s Toothpaste" demonstration is proposed. The catalyzed decomposition of H2O2 by iodide ion (I-) is employed to produce foam in a controlled fashion. The time at which the foam reached a known volume in a conventional 500 mL measuring cylinder was registered. A straightforward correlation was observed between foam production and v/V% in a given range. A correlation plot was obtained, and the concentration of unknown solutions "A" and "B" was then estimated from it. This simple and effective laboratory activity is proposed as a learning activity for comparing and analyzing results from both this quantitative approach and titration method reported by scientific literature.