Elephant toothpaste

Monday, 10 February 2020: we turned the famous elephant toothpaste demonstration into a real science experiment, in our grades 5-8 science class.  The demo is just the mixing of hydrogen peroxide solution with yeast so that the catalase enzyme in yeast rapidly breaks down the peroxide; detergent added earlier allows voluminous foam to form.  We tested that boiling and then cooling the yeast denatured the enzyme, eliminating the reaction.  In contrast, when we used manganese dioxide obtained by cutting open an alkaline cell, its catalytic action was unaffected by boiling.