Oxygen is a vital component of the air in our atmosphere. We need to breathe it in to survive, as do most other organisms. It is also necessary for combustion reactions, such as fire. In this experiment, we will test the relationship between oxygen and fire.
– large glass jar
– 2 cups of hydrogen peroxide
– baker’s yeast
– a bottle (1 liter soda bottle or wine bottle will work)
– a balloon
– a teaspoon
– safety glasses
Put on your safety glasses.
Fill your bottle with approximately 2 cups of hydrogen peroxide. Then, add about 1 teaspoon of yeast to the peroxide. Quickly open the balloon over the opening of the bottle making sure no air can escape.
Gently, shake the bottle back and forth to mix the yeast and peroxide. You should now see bubbles beginning to form. These are oxygen bubbles created by the decomposition of the hydrogen peroxide. The yeast acts as a catalyst for this reaction.
The oxygen should be inflating the balloon. Let this reaction go on for a time.
Meanwhile, light your candle and then cover it with the jar. Watch what happens to the flame. Don’t get too close to the jar. If it is weak, it could crack.
Uncover your candle and light it again.
Look at your balloon. It should be partially inflated. Pinch the open end of the balloon and carefully take it off the bottle making sure no oxygen escapes. Keep the end pinched closed.
Cover your lit candle with the jar again. This time, tilt the jar just enough to slip the open end of the balloon inside. Slowly, let the oxygen out of the balloon. What happens to the flame?
What Happened? Oxygen and Fire Experiment
Oxygen is necessary for fire. When the jar was placed over the candle the first time, the flame went out when all the oxygen was consumed.
We created oxygen when the yeast was mixed with the hydrogen peroxide. Hydrogen peroxide is not a stable compound. It is always decomposing into water and oxygen. It is kept in dark bottles to slow this reaction.
Yeast acts as a catalyst to speed up the decomposition of hydrogen peroxide. This is how we are able to collect a balloon full of oxygen.
When the oxygen from the balloon was placed into the jar with the lit candle, you should have seen the flame grow brighter. This was caused by the increased amount of oxygen in the jar. Fire actually burns faster (and appears brighter) when the oxygen concentration increases.
In this Steel Wool and 9 Volt Battery experiment, you can also see how the presence of heat and oxygen causes a combustion reaction and fire.
Physical Science Lesson
You can find this experiment in Module 2 of Apologia’s Physical Science curriculum. This module is all about air, it’s components, and their relationships to life on Earth.
This is our 4th year using Apologia science with our daughter. She loves it and wouldn’t consider another curriculum when choosing science for 8th grade.