Pressure Cooker

boiling water in a low pressure syringe

In this demonstration, warm water is placed in a plastic syringe, the syringe is sealed, and the plunger is pulled back causing the water to boil. The water boils because the action of pulling back the plunger increases the volume, thus decreasing the pressure. The boiling point of a liquid is dependent on the pressure of the system, so a decrease in pressure leads to a decrease in boiling point.

Marshmallow Magic

When a marshmallow is placed in a large capped syringe and the plunger is pushed in, the air in the marshmallow contracts from the pressure. Conversely, if the plunger is pulled back, the pressure decreases causing the air in the marshmallow to expand.

Water Flowing Uphill

A candle is placed in a crystallizing dish containing water and lit. A beaker is placed upside-down over the candle. The candle will eventually go out and the water level in the beaker will rise.
CxHy­ (wax) + (x +y/4)O2 (g) → x CO2 (g) + (y/2)H2O (l)