Blow up a balloon without using your lips!
You will need:
funnel (clean and dry)
small-mouthed bottle, large test tube or beaker
What to do: Pour about 1/2 to 1 inch of vinegar into the bottle. Turn the funnel upside down on a table and stretch the mouth of a balloon over the small end of the funnel. Fill the about half of the balloon with baking powder. Remove the balloon from the funnel, then while letting the full end of the balloon dangle over the side of your bottle, stretch the mouth of the balloon over the mouth of the bottle. When you're ready for some excitement, tip the baking soda out of the balloon and into the vinegar. Continue to hold the balloon onto the bottle so it doesn't fly off...
What happens: When the baking soda mixes with the vinegar, bubbles form and the balloon starts to inflate.
Why: There is a chemical reaction between the baking soda and the vinegar that forms carbon dioxide gas (the gas in the bubbles and the gas that fills the balloon). The gas continues to form as long as there are enough reactants (the baking soda and vinegar) for the reaction to continue.
What happened when CKS tried it: It starts to form bubbles and it hissed. The balloon gets bigger until the bubbles start to go down. We used water balloons and they were too small - we couldn't fill them with very much baking soda and there was enough gas to fill a bigger balloon so next time we'll use a regular balloon.
CKS also tried testing for the carbon dioxide gas: Add the baking soda to the vinegar in a clear glass (so that you can see what's happening inside the glass). Have a parent light a candle and see that it burns bright in the air. Slowly lower the candle into the glass to see what happens.
Carbon dioxide is heavier than air and sits at the bottom of the glass near where the vinegar and baking soda reacted to form those carbon dioxide bubbles. When the flame of the candle enters the carbon dioxide layer at the bottom of the glass - poof! - it goes out with no oxygen there to feed the flame.
CKS rating: 4 stars - better than toys!