Carbon dioxide extinguishes flames

Carbon dioxide extinguishes flames

ZIMSEC O Level Combined Science Notes: Experiment: Demonstrating that carbon dioxide extinguishes a burning flame

Aim: to show that carbon dioxide extinguishes a flame

Materials:  3 different sized candles, vinegar, baking soda, beaker or plastic bottle, shallow dish


  1. Place the 3 pieces of candle in a shallow dish
  2. Light the candles
  3. Mix vinegar and baking soda in a plastic bottle to make carbon dioxide
  4. “Pour” the heavy carbon dioxide gas into the shallow dish, being careful not to pour out the liquid into the dish/onto the candles

Results and Observations

  • The shortest candle goes out first followed by the mid sized candle
  • The largest candle piece goes out last provided it’s shorter than the sides of the dish in which it is standing


  • Carbon dioxide is evolved when baking soda is mixed with vinegar
  • Carbon dioxide is a heavy when compared to normal “air”
  • Carbon dioxide extinguishes flames
  • It is commonly used to fill fire extinguishers

NB Vinegar is made from ethanol

To access more topics go to the Combined Science Notes page.