Carbon Dioxide Candle Experiment

Carbon Dioxide Candle Experiment

Contributed by David Jiang


  • We’ve all seen fire extinguishers before and its powerful stream of nitrogen which can smother a dangerous fire. However, imagine a fire extinguisher that can take out fires “invisibly”. Here is a fun experiment to design your very own, invisible fire extinguisher.


  • 2 regular-sized cups
  • Matches/Lighter
  • 1 candle
  • Vinegar
  • Baking Soda


  1. Put in a couple tablespoons of baking soda in a cup
  2. Pour a little bit of vinegar into the same cup and wait for the reaction to settle down
  3. Put a candle in another cup
  4. Use a match/lighter to light up a candle
  5. Use the cup and tilt it over the cup with the candle 
    1. Make sure to not pour the liquid onto the candle

Physics Concepts and Questions

  • Fire requires oxygen to burn
  • The baking soda and vinegar makes a chemical reaction that makes carbon dioxide gas
  • When you pour the carbon dioxide gas over the candle, it pushes the oxygen out of the the cup
    • This is because carbon dioxide is heavier than oxygen, so CO2 sinks, and O2 rises
  • There is no oxygen to fuel the candle anymore, so the fire goes out

Conclusions and Further Investigations

  • Now that we have tested this experiment, it is time to look for other interesting ways to manipulate our extinguisher:
    • Does the type of vinegar affect the performance of the extinguisher?
      • Compare the time it takes for one type vs another
    • What happens if you try to extinguish the candle when it’s not inside a cup?
      • Does this make it harder/easier to extinguish? Or will it extinguish at all?