Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: horo1988 on October 31, 2007, 03:18:35 PM
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I did this experiment at home.
I burned a candle and left it for 10 secs. Next, I held a wood splint on the flame to burn it. I quickly removed the splint, n blew out the candle. So here was what happened: every single time I held the spint about 1/4 inches away from the smoking lick of the candle, the lick started flaming up again .
The question was why did it happen?
I tried to test this experiment again, but this time I left the lick until all the smoking is gone, n then held the splint near the lick, noting happened.
So I believe there is somthing to do with the SMOKE.
THe smoke is composed of Carbon dioxide and water vapor ... so why can a burning, flaming wood splint can flame up a smoking lick?
I 'm glad to hear from u guys, thanks alot ;)
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This interesting experiment has more to do with what you can't see than what you can. It seems to be a good demonstration of what happens when a candle burns. When things burn, there are three things that are required. There must be fuel, an oxidizer, and an ignition source (activation energy). Having all three of these things present may not always be sufficient. If your fuel and oxidizer are not properly mixed, it will be harder to ignite them and produce a flame. When a candle burns the hydrocarbon fuel (wax), is transformed from a solid to a liquid by the candle flame. This facilitates the transport of the liquid fuel up the wick via capillary action. Then what you probably don't see, is the vaporization of that liquid wax from the tip of the wick before it burns in the flame. These phase changes should give you a better idea of why it is possible to relight a candle without touching the wick with a flame (ignition source) when it is still warm, but it is impossible to relight it in the same way when it is cold. The science associated with flames and deflagration in general is quite interesting. You may also want to look at this page about candle flames in microgravity.
http://science.nasa.gov/headlines/y2000/ast12may_1.htm
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Dear Horo1988,
The Experiment is well known, and was celebrated thousand of times in class rooms.
I believe that the smoke is only “the visible” part of the phenomenon that is always “analysed”.
The real Actor is invisible and is called “WAX”/"Paraffin", - NO, to be more precise: some VAPOR of WAX.
In case you blow out the candle with not a to strong “wind”, the candlewick remains slightly “hot” and generates a small “Bubble” of a Wax/Air mixtures around the wick that is normally of a larger diameter then the visible smoke.
As long as the “Bubble” is not too diluted, you are able to ignite the Bubble and as long as the wick remains hot enough to still produce a miner part of wax vapour the wick will ignite too.
But it may be a nearly coincidence that when the smoke got invisible, also enough time has passed to dilute the Wax “Bubble” below the concentration for possible ignition too.
I’m able to think of several easy Experiments that can give evidence for or against this these.
Good Luck!
ARGOS++
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Thank you so much invisiblegs and ARGOS++
I get it now :)
To invisiblegs: Hi, I just wonder what you have told me, 3 things to burn one thing: fuel, oxidizer, and ignition source.
For the candle case, what is the oxidizer? is it Oxygen?
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In short, yes. Air is the source of oxygen that serves at the oxidizer in this case.