Endimion17
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Hydrogen in chlorine flame sound
I've just had a funny and weird experience.
Have you ever noticed a peculiar sound this flame produces? It's rarely quiet.
I've just burned some hydrogen in 1L flask to take some nice photos, and there was this weird WOOOOOOO sound. Kind of the sound of microphonics, but
low pitched.
I uploaded the video so check for yourself.
<iframe sandbox width="480" height="390" src="http://www.youtube.com/embed/nUzugUuwFVA" frameborder="0" allowfullscreen></iframe>
(sorry about the crumbled background)
Touching the flask does nothing, so does covering the neck, and the lower the flame is positioned in the flask, the louder the sound. And it can be
really, really loud. It got so fun dipping the flame that I forgot it was midnight so I woke up some people on the upper floor, made them come down
and use foul language. 
Putting hand above the neck of the flask (hydrogen chloride mist comes out; well what the heck, you live only once, and I've got some hand lotion to
soothe the pain) reveals tingling vibrations of the air column.
What the hell just happened? It's just warm HCl exiting a flask. Mind that this happens in smaller flasks, too.
I think it's some kind of resonance between the flame and the warm gas exiting the flask neck, because as soon the sound is made, the flame gets all
messed up. It reminds me of Ruben's tube.
Now I'd like to try this with a much larger container.
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hkparker
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Very cool! thanks for sharing.
My YouTube Channel
"Nothing is too wonderful to be true if it be consistent with the laws of nature." -Michael Faraday
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MrHomeScientist
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Neat video. I'm sure it's just resonance - the same as when you blow over the top of a glass bottle (the sound is nearly the same, too). The reaction
creates a warm gas, which quickly rises out of the flask and sets up some resonance with it. The tingling sensation you feel is your flesh dissolving
in HCl 
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blogfast25
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Quote: Originally posted by Endimion17  | What the hell just happened? It's just warm HCl exiting a flask. Mind that this happens in smaller flasks, too.
I think it's some kind of resonance between the flame and the warm gas exiting the flask neck, because as soon the sound is made, the flame gets all
messed up. It reminds me of Ruben's tube.
Now I'd like to try this with a much larger container. |
If it's resonance (almost certainly true), the pitch should be in accordance with the flask size: small flask, higher pitch, - larger flask, lower
pitch.
Looks like you've created a HCl fuelled saxophone!  Sure beats 'whale songs'!
[Edited on 22-8-2011 by blogfast25]
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FrankRizzo
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I believe the hydrogen is reacting in an oscillatory manner at the tip of the tube (flashing inside the tube and back out). That oscillation is then
resonating the volume of gas inside the flask.
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Endimion17
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This should be repeated with oxygen instead of chlorine. Something tells me that chlorine's large density helps with the resonance.
It would be just awesome if the flask cracked...
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Morgan
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Here's some 1802-3 vaguely related subject matter, maybe a few crumbs.
http://www-chaos.engr.utk.edu/hst/delarive-philmag-14-iv.htm...
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blogfast25
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| Quote: Originally posted by Endimion17 | This should be repeated with oxygen instead of chlorine. Something tells me that chlorine's large density helps with the resonance.
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http://en.wikipedia.org/wiki/Speed_of_sound
"For different gases, the speed of sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser
extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a type of compression.
Although, in the case of gases only, the speed of sound may be expressed in terms of a ratio of both density and pressure, these quantities are not
fully independent of each other, and canceling their common contributions from physical conditions, leads to a velocity expression using the
independent variables of temperature, composition, and heat capacity noted above."
But the resonance (standing sound waves) should really only depend on the size of the cavity, I think... 
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watson.fawkes
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Characteristic wavelengths depend on the boundary conditions, i.e. the
cavity. Speed of sound determined by chemical composition and physical conditions (such as temperature). Combining the two gives you frequency.
Q: What new?
A: Vee over lambda, of course.
Q: Asshole.
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blogfast25
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So the pictch, for a given cavity, would depend on the gas used.
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Morgan
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| Quote: Originally posted by Endimion17 | I've just had a funny and weird experience.
Have you ever noticed a peculiar sound this flame produces? It's rarely quiet.
I've just burned some hydrogen in 1L flask to take some nice photos, and there was this weird WOOOOOOO sound. Kind of the sound of microphonics, but
low pitched.
I uploaded the video so check for yourself.
<iframe sandbox width="480" height="390" src="http://www.youtube.com/embed/nUzugUuwFVA" frameborder="0" allowfullscreen></iframe>
(sorry about the crumbled background)
Touching the flask does nothing, so does covering the neck, and the lower the flame is positioned in the flask, the louder the sound. And it can be
really, really loud. It got so fun dipping the flame that I forgot it was midnight so I woke up some people on the upper floor, made them come down
and use foul language.
Putting hand above the neck of the flask (hydrogen chloride mist comes out; well what the heck, you live only once, and I've got some hand lotion to
soothe the pain) reveals tingling vibrations of the air column.
What the hell just happened? It's just warm HCl exiting a flask. Mind that this happens in smaller flasks, too.
I think it's some kind of resonance between the flame and the warm gas exiting the flask neck, because as soon the sound is made, the flame gets all
messed up. It reminds me of Ruben's tube.
Now I'd like to try this with a much larger container. |
I saw this "chemical harmonica" at the end of the video the other day and decided to try propane in a flask just to see if it would make a tone.
Experiment No. 3: Testing three gases (basic knowledge) + Bonus material: Hydrogen Harmonica
https://www.youtube.com/watch?v=mKmdtja3fbA
Some propane attempts
Singing Flame with Erlenmeyer Flasks
https://www.youtube.com/watch?v=azAe33w2iCI
Chemical Harmonica Using Propane and Bottles
https://www.youtube.com/watch?v=hHKmMrlxo24
Resonant Cavity with a Propane Flame
https://www.youtube.com/watch?v=h5UIjYh3-70
[Edited on 2-12-2023 by Morgan]
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averageaussie
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| Quote: Originally posted by Endimion17 | This should be repeated with oxygen instead of chlorine. Something tells me that chlorine's large density helps with the resonance.
It would be just awesome if the flask cracked... |
I dont think thats a great idea...
2 H2 + O2 = 2 H2O + a LOT of energy, much more than H2 + Cl2 = 2 HCl (-482 kJ vs -185 kJ)
using oxygen will likely just make the mixture explosive, and when we have an explosion (or an explosive) in a confined space (like glassware), we get
what we call in the industry a "bomb" or a "grenade"
Not exactly safe, sending glass shards everywhere.
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