- Aluminum Pie Tin
- 3" Candle
- 1 Cup of Water
- Safety Matches or Long Nosed Lighter
- 1 Pint Jar
Ask an adult to help you light the candle. Let a bit of wax drip onto the pie plate and secure the candle to the pie plate in the drippings. Pour the water, (food coloring optional), into the pie plate. Watch what happens as the candle extinguishes.
What's going on?
While the flame appears, oxygen inside the jar is consumed. The reduction of oxygen is not the reason for water climbing upwards. The combustion of hydrocarbons, (such as wax), produces both carbon dioxide and water. Water condenses against the glass jar and carbon dioxide can slip under the jar lip or dissolve in the water. The gaseous volume inside the jar decreases, pressue decreases inside the jar, so water moves up even as the flame is glowing. After the flame goes out the remaining gases cool, decreasing the air pressure inside the jar further. More water is pushed into the jar by greater atmospheric pressure outside the jar. This experiment works best with a jar that has a skinny neck and large base.