DIY Science: Measuring the Invisible
Here’s a fun experiment that we piloted at Donoghue Elementary School yesterday: how do you measure something that is invisible? Gases are all around us, but we can’t see them. Using our senses though, we can hear wind blowing through leaves, smell coffee brewing in the morning, and feel air conditioning blowing against our skin. These are all gases!
So how can we measure how much of a gas there is if we can’t, say, grab a handful of it? Let’s do this fun experiment!
You will need:
Plastic water bottle, filled halfway with water
Effervescent antacid tablet (Alka-seltzer)
1. Place the antacid tablet in the balloon and crush it by breaking it apart with your fingers.
2. Secure the mouth of the balloon over the water bottle spout.
3. Tip the balloon to dump our the antacid pieces into the water.
4. What do you observe?
The antacid tablet contains an acid and a base, and they mix together in the water to create gases. We detect these as the bubbles in the water. The gases then inflate the balloon! Some balloons will inflate more than others, depending on the amount of gases created. So using balloons, we can qualitatively ‘measure’ the amount of gases created, even though they are invisible! You can repeat this experiment with multiple antacid tablets, or try shaking the bottle to create more gases.
(thanks to howtosmile.org for original experiment!)