Here is a fun, and easy, chemistry experiment you can do with your kids.
Hydrogen Peroxide (3%)
Food Coloring (optional)
Aluminum Foil (optional – but it helps contain the mess)
A small cup or bowl to mix the water and yeast
A small bottle or cup for the reaction
Mix a packet of yeast with 2 or 3 tablespoons of warm water and let stand for 5 minutes or so. (I had the kids do this first and then it was ready by the time they finished the rest.) Note: we folded up the packets and used them as stir sticks, and it worked very well.
We used some aluminum foil to make disposable trays that would contain our mess. (Make them bigger than you think – we almost overflowed ours).
Poor the hydrogen peroxide into the bottle (or bowl or whatever you are using for the reaction). Add some food coloring and mix it in. Then add a few squirts of the dish soap. Swirl the bottle around so that the soap mixes with the water, but try to avoid making bubbles.
Now pour the yeast mixture into the hydrogen peroxide and watch it foam. When the reaction stops, try swirling the bottle again and you might get it to restart (if there is still hydrogen peroxide left).
What is happening?
Hydrogen peroxide has the chemical formula H2O2, which means each molecule has 2 hydrogen atoms and 2 oxygen atoms. The yeast works as a catalyst in the reaction. A catalyst is a chemical that triggers a reaction, but is not actually used up. So nothing really happens to the yeast. All of the excitement is with the hydrogen peroxide. One of the oxygen atoms breaks off of the H2O2 resulting in H2O and a free oxygen atom. That free atom bonds with another free oxygen and form O2. So the result of the reaction is water, oxygen, and a little bit of heat.
Since we are starting with safe materials, and ending with yeast, water, and oxygen, it is safe to touch the foam and play with it. Our kids had fun writing in it. They also had fun holding their hand over the top of the bottle while pressure from the reaction built up and then picking their hand up. This got a little messy, but it was fun.
The soap is added so that we get foam instead of just having oxygen gas rising out of the bottle (that would not look very exciting).
Because heat is given off when the bonds break, we call this an exothermic reaction.
Have fun exploring the chemistry of God’s Creation.