Science of Gases

Still very much in catch up mode!

Our tour through science of matter arrived on gases several weeks ago.

To illustrate the presence of gas (specifically oxygen) we stood a lit candle in a bowl of water and placed a jar over the top.  When the oxygen was burnt up the candle went out and the water in the jar rose.  I was expecting it to rise slowly as the oxygen burned but it suddenly goes up as the candle extinguished.

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We showed how gas could be made through chemical reactions by mixing baking soda and Kool-aid (contains citric acid).  You can of course use vinegar but this smells better.

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We then looked at the effect of heat on gas.  By microwaving marshmallows for different time periods and watching them expand.

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We then had a bit of fun creating marshmallow faces.20141007_45 20141007_46

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We finished up the group by making hovercrafts.  Inflate a balloon and slip it over the top of a sports drink bottle lid (with the lid closed).  Attach the lid to the middle of a cd with sticky tack.  When you open the lid the air from the balloon rushes out through the centre of the cd and it slides across the table on a cushion of air.

20141007_49Final trick of the week was just playing in the kitchen later in the week.  Full glass of water with a piece of card on top.  Turn the glass over and take away hand and due to the air pressure from below, the card and all the water in the glass stay in place.  Was very pleased it worked as I would have been rather soggy had it not.

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