Everybody knows fire and water don’t mix—if the fire’s too hot, all your water will evaporate; if there’s too much water, the fire will be doused. But to get hot water in your house, you may very well have a water heater that uses actual flames to heat the water. Beyond the shower or washing machine, with the proper setup, that hot water can be used to heat the house itself.
Ergo, water must absorb heat pretty darned well. And, this heat absorption almost certainly affects other materials in contact with the water. But, how to demonstrate such a thing in a fun and easy manner so kids (or whoever) can wrap their little minds around the idea?
Burn, Baby, Burn!
This easy-peasy-lemon-squeezy Demo Science science demo requires but five items: two identical balloons, water, a funnel, and a lighter. The balloons don’t have to be 100 percent identical—they can be different colors—but they should be roughly the same size and shape.
First, inflate one of the balloons with just air and tie it closed. Put about ¼ cup to ½ cup of water in the second balloon with your funnel, then inflate it with air to roughly the same size as the first balloon and tie it closed.
Then, hold the air-only balloon by the knot in the end so that it hangs down. Flick your Bic and place the open flame under the balloon. It should take almost no time at all before POP! One exploded balloon: check.
Take the second, air-and-water balloon and hold it in the same manner. Hold the lit lighter under the balloon and observe. Hmmm… no explosion. BORING! But, why didn’t this balloon blow like the first one?
Is It Something to Do with Thermal Science?
It sure is, dear reader. Well done! The first balloon burst because the flame heat it up very quickly, weakening the rubber of which it’s made. The weakened rubber can’t resist the expanding air pressure inside the balloon, and it popped.
The water inside the second balloon absorbed most of the heat from the flame. The rubber itself was, of course, heated somewhat, but the water bore the brunt of it. Thus, the rubber doesn’t weaken and the balloon remains strong enough to resist the air pressure inside it.
The only medium available to absorb heat in the first balloon was air. The water in the second balloon absorbed enough heat to prevent its destruction. From this, we can extrapolate that water is a far superior heat absorption medium to air.