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Wednesday, 16 March 2016

Candle Light

Candle Light

I began with a big safety rant about being sensible and being aware of the dangers involved with flames, how to light matches, and what to do in case of accidents, going over various possible scenarios. (I hate lecturing learners but in this case it was necessary.)

With that out of the way we got down to the business of learning about the actual flame of a candle. Everyone had flames to observe and it was amazing all the different colours that were visible, the feel, and smell of the flame burning the wick when we really used all our senses. Some students used devices to investigate what the different colours of the flame indicated while others sketched what they could see.

Next was to experiment to see what would happen if a live match was brought close to the flame compared to a dead match. There were lots of 'jumps' and the occassional 'bleep' word when this happened. The dead match was nowhere near as exciting but the great question was 'why' was there this difference in reaction from the match?

The students then extinguished the cande and immediately held a burning match in the smoke wafting up from the candle. It was amazing to see the flame jump down the smoke to reignite the candle. After a discussion in which various theories were debated, experimented with, and some eliminated, the students were able to talk about the gases in the smoke being responsible for this.

Predictions were made about what would happen when a saucer was held close above the candle flame? This gathered a variety of responses, from melting the saucer to black ash, with some very astute predictions following on from our Methane gas model. This is what we observed. Black smoke from incomplete combustion, known as soot.

Our final experiment of the day involved predictions of what would happen if an inverted jar was placed over the candle. There was no fooling these guys as we had had so many discussions involving the need for oxygen and the production of carbon dioxide and water over the week that they all knew the candle flame was not going to survive! So the task was to experiment with different sized jars and various sized candles to see if there was any difference in the time it took for the flame to extinguish.

Their findings were that the smaller the candle and the larger the jar then the longer it would take for the flame to die out. And we managed not to set off any smoke alarms!

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