Experiment: Rising Water

• what do you need?

  • a shallow bowl/dish
  • a candle
  • water with added food colouring drops
  • a lighter
  • a large glass jar
  • a thermometer
• what do you do?

  1. put the candle onto the plate.
  2. pour approx 1/2 to 1 cup of water onto the plate.
  3. light the candle, then place the jar upside down over the candle.
  4. take temperature readings as the candle burns.
  5. write down your findings.
• what's happening?


  the candle heats and expands the air. This cancels the depletion of the oxygen temporarily and the water level stays down. When the oxygen is depleted, the candle goes out and the air cools. The volume of the air decreases and the water rises.
• the chemistry behind it:

  oxygen and paraffin react. The burning produces water and carbon dioxide. Twice as much water is burned than carbon dioxide released so the air volume decreases.