Candles

 

It was one of my students birthdays last week. The student brought in a cake, I had a candle, we lit it, sang happy birthday, etc ….. and then had a remarkably good discussion into wjat happens during the combustion of a candle.

What is actually burning? The students asked. The wax? the wick? both? neither?

By Matthew Bowden www.digitallyrefreshing.com (http://www.sxc.hu/photo/148763) [Attribution], via Wikimedia Commons

This is actually a good discussion to have if you are about to teach this organic Chemistry topic.

What happens it this – the match (or lighter) melts the wax. The wax rises up the wick (by what process, capillary action?) and the head of thematch provides suffiecent activation energy to start the reaction between the wax and oxygen. The reaction is exothermic, so it produces sufficent heat to melt further wax and the process becomes self sustaining.

And if the students don’t buy into this? At least you will have had a nice piece of cake! 😆

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