Burping Bottle
Brief Description
This demonstration shows the relationship between temperature, pressure, and thermal expansion of air. Cooling the bottle lowers the air pressure inside, and warming it increases the pressure. The rising pressure pushes air against the coin covering the bottle until the coin lifts and air escapes, similar to how pressure buildup in the stomach causes burping to release gas.
Materials
Water, oil, a dime, and a glass coke bottle.
Setup
To set up this experiment, add a little water to the coke bottle and allow it to cool for at least an hour. This gets more effective as the bottle is allowed to cool for longer.
Performing the Demo
Right after the bottle is introduced to room temperature, rub oil around the cap of the bottle and cover it with a dime. As time goes on, the dime will continue to lift and drop. This behavior can be heard by the audience.
