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Re: candle flame question

Does anyone have an explanation of the shape and color ??
Jim Braunsdorf

There was a little more discussion of this phenomenon on the
CHEMED-L list in which I added to my observations much of what you observed
-- a more spherical flame. Flames in microgravity (orbital experiments)
have spherical shape due to the fact that convection doesn't work normally.
It is likely that as the pressure drops, the "strength" of the air currents
(for lack of a better term) decrease.
I've discussed this with several people and the consensus seems to
be that while the oxygen supply MUST be decreasing, the fuel supply must be
decreasing even more so to give the blue "complete combustion" flame. As
the oxygen level drops, the rate of combustion decreases and the heat
available to melt and then vaporize the wax lowers. The diminished heat
(and heat transfer at low pressure?) is what cuts down on the fuel supply.

This has all been done qualitatively of course. :) The answer is
still open to argument so if there are any new ideas...let's have 'em!


p.s. If there is interest I will try to dig up the CHEMED-L responses
(one which detailed what chemical species give what colors) and cross-post
them here. Let me know

-- Chris Clayton
(first year physical science teacher)
Mt. Zion Senior High School
305 S Henderson
Mt. Zion, IL 62549

(currently forwarding to:
MSN Chemistry Forum Assistant

"Life is a vector quantity."