Breaking Down a Breakdown Reaction

In grade 10 science, the chemistry unit is primarily focused on chemical reactions.  Simply discussing the various types of chemical reactions and what they entail can be for many students a bit abstract. Luckily for chemistry, there are a lot of “cool” demonstrations (or demos as we call them in the biz) that can be utilized to visually represent the power, speed and awesomeness that chemical reactions can have.  One of the types of chemical reactions students learn about in grade 10 chemistry is a decomposition reaction in which a single reactant molecule breaks down into simpler constituents (parts).

2 H2O2 (l) à  2 H2O (l) + 02 (g)

On Monday October 15, our science class witnessed a decomposition reaction.  In particular this decomposition reaction was one used on the hit comedy series, The Big Bang Theory, and so aside from its “cool” factor, it also had pop culture factor and something the students could relate to.  The reaction is essentially the breakdown (decomposition) of hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2). Hydrogen peroxide is a liquid substance that can be found in drug stores and is used on cuts.  The drug store variety of hydrogen peroxides, are only 3%.  The hydrogen peroxide we used for our demonstration was 6 and 30 percent (to make the outcome more dramatic).

To make the reaction go really fast we mixed yeast in warm water and added it to the hydrogen peroxide (the yeast speeding up the reaction significantly).  Added to the hydrogen peroxide before hand was food colouring (for cool effect), and ordinary dish soap.  The oxygen that is released during the decomposition is caught by the dish soap bubbles which causes the liquid to expand as it does.  The outcome is a fun and “cool” demonstration of a decomposition reaction, which is a lot better than simply describing its mechanics.

Check out the rest of the pictures on our Facebook Page!

Oct 24th, 2012 – Breakdown Reaction Lab