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Re: What makes blue flames blue?

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  • Greg Zukowski
    In a nutshell the blue flame is an energy drop fromt he yellow flame, not an energy increase- Here s how my chemist friend explains the color difference: The
    Message 1 of 4 , Feb 4, 2005
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      In a nutshell the blue flame is an energy drop fromt he yellow
      flame, not an energy increase-
      Here's how my chemist friend explains the color difference:

      The yellow-orange emission is nearly true black-body, note that a
      flame casts a shadow if light is shined on it, but fortunately the
      blue is way too thin to be a true black-body. If it were, the
      radiation power of the blue part would be (600/400)^4, or 5 times
      that of the yellow flame; candles would be really dangerous! The
      reactions producing blue light must have electrons dropping about 3
      volts, about right for a carbon-to-hydrogen bond to oxygen-to-
      hydrogen bond energy drop.



      --- In woodheat@yahoogroups.com, "meed7" <meed7@y...> wrote:
      >
      > I have always understood that the yellow flames seen above
      candles,
      > wood fires, etc is due to incandescent particles heated by the
      actual
      > flame to the point where they emit yellow light... I guess to put
      a
      > number on it this, the temperature would be somewhere in the 1000-
      > 2000 C range.
      >
      > But what makes the blue flame, seen for example on a gas stove and
      > also at some places and times in a wood stove, blue? Since the
      > temperature for "blue-hot" on the blackbody scale is well beyond
      > 10,000 C, I don't think I'm seeing light emitted by incandescence
      > (otherwise we'd have to wear welding goggles to look into our
      stoves).
      >
      > Is the blue that we see the characteristic wavelength of, say,
      carbon-
      > oxygen combustion, or perhaps hydrogen-oxygen combustion? Anyone
      > know?
      >
      > I have an inquisitive 9-year-old who has been asking these kinds
      > of "why is the sky blue" type questions... and of course, to
      > appropriately simplify the answer, one has to know much more than
      > just the answer!
      >
      > regards,
      > Ed
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