How Does It Work
You might remember treating a scraped knee or a cut with hydrogen peroxide. H2O2 is the chemical formula for hydrogen peroxide which shows it’s made up of two hydrogen atoms and two oxygen atoms. H2O2 looks like ordinary water (H2O), but the addition of that extra oxygen atom turns the molecule into an extremely powerful oxidizer. The hydrogen peroxide found at the grocery store is a 3% solution which is safe to touch but powerful enough to kill bacteria, viruses, and fungi on surfaces.
The hydrogen peroxide used for this demonstration is four times stronger than the over the counter variety you can buy at the store. Low percentage hydrogen peroxide (3%) is great at home but will not produce the massive amount of foam seen in the this effect.
The secret to this reaction is actually the catalyst – the yeast mixture – that speeds up the decomposition of the hydrogen peroxide. This catalyst releases the oxygen molecules that are contained in the hydrogen peroxide molecule. When H2O2decomposes, it breaks down to form water (H2O2) and oxygen (O2). The soap bubbles that erupt from the pumpkin are actually filled with oxygen.
As the reaction takes place, you’ll also see water vapor (yes, water vapor) rising out of the erupting foam. This shows that the reaction is exothermic, or that it gives off heat during the decomposition. As the bonds break between the H2O and O2, they release energy in the form of heat. Do the reaction in a cup and feel the sides of the cup. They’ll be warm!
