The goal of this activity is to introduce chemical reactions and limiting reactants in an attention grabbing way. First the elephant toothpaste reaction is set up, a fairly common chemistry lab activity that involves the decomposition of hydrogen peroxide to water and molecular oxygen. Second, they will be introduced to the concept of limiting reactants with the now famous Mentos and diet cola reaction (preferably outdoors). While this reaction is not technically speaking a chemical one, it can be used to simply illustrate the point of limiting reactants by showing that less Mentos results in a shorter jet of diet cola, and more Mentos results in a higher jet of diet coke.
1. Explain what a decomposition reaction is and give an example
2. Explain the concepts of limiting reactants and their effect on reactions
Lesson Materials (view or download)
reactions, elephant toothpaste, Mentos and coke
Last updated: 3/9/2015