Step-by-step tutorial
Warning
Do not point the bottle at anyone as you pump it up, and wear eye protection for this experiment.
Step 1
Gather your materials.
Step 2
Use the awl to make a small hole in the bottle cap.
Tip
For our younger scientists, ask for a grownup’s help with this step!
Step 3
Slide the needle of your pump into the hole, and add some clay to the inside of the cap. Squeeze the bottle to make sure it's air-tight.
Step 4
Pour a small amount (roughly 1 tablespoon) of rubbing alcohol into your empty bottle and screw the cap back on.
Step 5
Swish the rubbing alcohol around so that it covers the walls on the inside of the bottle.
Step 6
Pump up the bottle! The more you pump, the more dramatic your result will be! We pumped about 40 times. Just make sure to keep the bottle air-tight.
Step 7
When you're done pumping, hold onto the bottle firmly and twist open the cap to release the pressure. (A loud popping noise will occur, so any onlookers around may want to plug their ears.) A cloud will instantly form inside!
Learn more
So what's happening?
This trick works thanks to pressure. The more air you pump into the bottle, the more you increase both the pressure and the temperature inside the bottle. (We could actually see the air pressure push out the bottom of our bottle!) This makes some of the alcohol and water droplets in the bottle turn into a vapor.