Monday, May 2, 2011

Candles Suck

You will need:
·         A night light candle
·         A jar that fits over the candle
·         A bowl of water
·         Matches
·         An attentive adult
Place the candle in a bowl of water and light the candle.  Place the jar over the candle. This experiment is so popular because of what happens next … The candle will go out and then the water will be drawn into the jar.  Kids (and most adults we know) at this point make lots of oooohhh ahhh noises.
Often people then announce that the candle has burnt up all the oxygen.  As a result a partial vacuum is created and this draws the water up.  Unfortunately ...
 we have discovered this isn’t quite right.
Surprisingly, oxygen cannot be burnt as it is non-flammable gas. We cannot burn anything without oxygen but the presence of oxygen just aids the fire – it doesn’t fuel it.  Try the experiment again and note when the water starts to move.
It moves after the candle has fully gone out.  If the burning of the oxygen created a vacuum, the water would rise up as the oxygen burns up. 
But what does happen??? When we place the jar over the candle all the gases in the jar heat up.  Heated gases have a habit of spreading out.  The candle starts releasing carbon dioxide.  This creates a new mixture of gasses and there is too much carbon dioxide in this new mix to aid the burning process. 
When the candle goes out the gases in the jar cool down.  As they cool, they contract and take up less space.  This contraction creates a partial vacuum and the water gets drawn up. 
Over the next four days we will be checking out different experiments that will help us understand the science behind the Candles Suck experiment even better.
Catch you tomorrow!


3 comments:

  1. I wont believe it! it is all a fake explanation

    ReplyDelete
  2. Hey Anonymous - you'll just have to try it and see :)

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  3. I tried this in science class the other day and Anonymous, let me tell you it is not fake!!! :D To anyone who says this is fake, please learn your science and don't go around making conclusions if you don't know anything about it. Or if you don't have any justifications either.

    ReplyDelete

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