Home-made Fire Extinguishers

Most homes and all schools and businesses have fire extinguishers. Fire needs heat, fuel and oxygen – fire extinguishers work by removing one of the critical ingredients for a fire - this experiment shows one way to do it – but make sure you have an adult with you when you try it!!!

What you will need

  1. Small Dish
  2. 1 big adult
  3. 1 or 2 Candles
  4. Large Bowl
  5. Baking Soda
  6. Vinegar

How to do it

  1. Fill the small dish with baking soda.
  2. Place a short candle and a slightly longer candle upright in the baking soda
  3. Place the dish into the bottom of the large bowl.
  4. Have your adult light both candles.
  5. Pour the vinegar into the dish of baking soda.

What happens to the candles?
Which candle goes out first - the shorter one or the taller one?

What is Happening?

When vinegar is combined with baking soda, the two react and produce carbon dioxide gas. The carbon dioxide gas is heavier than the surrounding air so it sinks into the bottom of the bowl. As the reaction continues, more and more carbon dioxide gas is produced which begins to slowly fill up the bowl. When the level of carbon dioxide has risen to the level of the flame, the flame will go out, because it needs oxygen – which the carbon dioxide is preventing reaching it.

Don't worry about the carbon dioxide – it does not smell, it is not poisonous, and plants breathe it in!


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