Burning candle produces CO2
Students learn that the burning process produces carbon dioxide (besides water)
Experiment # 1
Materials: a small candle, a glass beaker, plasticine
Procedure
- Place the candle upright using a piece of plasticine
- Place the mouth of the glass beaker 1 or 2 centimeters above the flame and wait (30 seconds or more). What do you notice?
What happens?
Besides heat and water vapour, a burning candle produces carbon dioxide, which can extinguish a flame.
Because of this characteristic, carbon dioxide is used for filling fire extinguishers.
Experiment # 2
Materials: a small candle, a glass beaker, a glass funnel, plasticine, bromothymol blue
Procedure
- Place the candle upright using a piece of plasticine
- Place a few drops of bromothymol blue on the inside surface of the funnel.
- Hold the mouth of the funnel over a burning candle and close with a finger the small end of the funnel.
- Wait about 30 seconds. What do you notice inside the funnel?
What happens?
The drops of bromothymol blue turn yellow.
That confirms that a burning candle produces carbon dioxide
(see respiration activities)
The burning reaction is:
Wax + oxygen ----> carbon dioxide + water + heat