Continuing on in Michael Faraday’s series Six Lectures on the History of a Candle, I want to look at another interesting development in the wonders of a candle.
Materials:
- One candle (a tea candle works great)
- Lighter or matches
- Saucer
- Transparent drinking glass
- Food coloring (optional)
Caution: Fire always requires the supervision of an adult. The adult should be the one handling any flame.
Experiment:
Place the candle in the center of the saucer and pour water around the candle and onto the saucer. Light the candle and let it burn for a bit. Place the glass upside down over the candle and observe.
What’s happening?
Did you see any air bubbles escaping from between the glass and the saucer? Because the air inside the glass is heating up and causing the air molecules to move faster than at room temperature, those molecules take up more space and some will escape by bubbling out of the water between the glass and saucer. As we saw in last month’s ChemShorts for Kids, the oxygen in the air is reacting with the candle wax to create carbon dioxide – the chemical you find in a fire extinguisher. As the oxygen is depleted and the carbon dioxide is created, the flame will eventually extinguish. Once the candle goes out, the air in the glass will cool down and not take up as much space. The water will begin to come inside the glass to fill that space and so we see the water rise inside the glass. You may have even see some air start to bubble inside the glass as the outside air will also try to fill that space.
Extension:
What happens if you use a bigger or smaller glass? What happens if you use more or less water? What happens if you use more candles? Try taking off the glass keeping it upside down, relight the candle and place the same glass over the candle again. Now repeat the experiment using a different glass? Does the candle burn longer, the same amount of time, or for less time?
References:
https://www.mombrite.com/burning-candle-in-water-experiment/
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts.
