In 1848, Michael Faraday wrote a series on the Six Lectures on the History of a Candle. I won’t go into them here, but suffice it to say there’s a lot to know about the burning of a candle.
We see candles burn at every birthday party and you’ve probably even seen magic candles that, when you blow them out, reignite. We will talk about magic candles later, but in this experiment, we will look at how we can light a candle without touching the flame to the wick.
Materials:
- One or two paraffin candles
- Lighter or matches
Caution: Fire always requires the supervision of an adult. The adult should be the one handling the flame. If you use a second candle for the experiment, you may want to protect the surface of the table with something so that wax does not drip onto it.
Experiment:
Light the candle and allow it to burn for a minute. Before you blow out the candle, have the other flame ready to go. The other flame might be from another candle, a match, or a lighter. Blow out the original candle flame and note the smoke that comes from the wick. Quickly, before the smoke goes away, put the second flame into the smoke. If nothing happens, move the second flame closer to the wick. Did the original candle relight? If not, try it again from the beginning.
What’s happening?
Just like you’ve seen with water existing in three phases (solid, liquid, and gas), candle wax can exist in those three phases as well. The wax starts out solid and once the candle is lit, you see the solid turn into a liquid. The smoke you see when you blow out a candle is gaseous wax. The flame can reignite that gaseous wax, and because the flame travels faster than the gas is floating away from the wick, the flame can get back to the wick and light it. It happens so fast that the naked eye can’t really see the flame travel, but there is some good slow-motion photography that allows one to see it: https://www.sciencealert.com/watch-the-science-behind-the-coolest-candle-trick-ever.
The magic candles that automatically reignite are made with metal particles (aluminum, magnesium, or iron) in the wick. You often see sparks fly out of those candles due to these metal particles getting very hot. Once you blow out the flame of a magic candle, the hot embers from the wick can reignite the metal and in turn, reignite the wax coming from the wick.
Extension:
Try different kinds of candle waxes such as beeswax, soy, coconut, etc. to see which gives you the best smoke to reignite.
References:
C&E News. “Why are trick candle flames so impossible to blow out?”
https://cen.acs.org/articles/88/i32/Trick-Candles.html#:~:text=Magnesium%20is%20a%20highly%20reactive,hydrocarbons%2C%20which%20relights%20the%20wick
Scientific American. “Make a Candle Flame Jump,”
https://www.scientificamerican.com/article/make-a-candle-flame-jump/
To view past “ChemShorts for Kids” activities, go to:
https://chicagoacs.org/ChemShorts.
