The invisible fire extinguisher
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From Roman candles to Catherine wheels - discover the science behind the colourful explosions of fireworks.
Discover the secret of the invisible fire extinguisher. This video shows you how to fight fire with baking soda and vinegar
The explanation
If you’ve watched the video above, Candletastic – the invisible force, you might be puzzled. What put the candles out? Was it a gas? Was it a liquid?
You can try this at home – but remember don’t let children handle matches or candles, and don’t leave lit candles unattended.
The vinegar and bicarbonate of soda make a gas – carbon dioxide. This is heavier than air and so sits in the jug. When you tip the jug, it pours out.
Flames need oxygen to burn (which is present in the surrounding air) – but when the carbon dioxide pours over the flame it pushes the available oxygen out of the way and the candle can’t burn any more.
Take a look at a normal (red) fire extinguisher, many contain carbon dioxide… but with a bit more fizz.
What could you do next?
- Check out Science courses at the OU
- Post clips of your science experiments as video comments on the YouTube page of candletastic (though please – no dangerous ones)
Content last updated: 04/09/2008
