How Much Oxygen is Used When Something Burns?

Written by Marcia Malory

This experiment will show how much oxygen is removed from the air when a candle stub burns.

Equipment needed

1 candle stub
1 bottle with no lid
1 flat soup bowl - flat enough for the bottle to remain upside down in it without falling over

The Experiment

Fill the dish with water.

Light the candle and carefully float it in the dish.

Once the flame is burning steadily, turn the bottle upside down and use it to cover the candle.

The candle will continue to burn for a few seconds because a small amount of oxygen is trapped inside the bottle.

However, the oxygen will be used up very quickly, and the flame will then go out.

The air pressure in the bottle will decrease as the oxygen is used up.

To equalize the pressure, the air outside of the bottle will press down upon the surface of the water of the dish, attempting to enter the bottle. This will force water into the bottle.

The amount of water in the bottle will indicate how much oxygen was used.

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