This simple experiment will help you find out how long oxygen in the air lasts. You will need a deep tray or trough, a glass jar, a piece of tubing, a candle and some matches.
Do NOT attempt this experiment if you have asthma or any other respiratory illnesses.
1) Fill the trough and jar full of water. Ask someone to hold the jar in the trough upside down. Place one end of the tube into the jar under the water.
2) Sterilise the end of the tube with a sterilising fluid (such as Milton) and breathe through it into the jar. You will find that the water will leave the jar and some air will be trapped.
3) Carefully place the jar over a lit candle.
4) Time the candle until it goes out. Write the result in your note book.
5) Repeat the experiment several times and work out the average time the candle burns.
