Yttrium2
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Sublimination?
When moth is smoked it goes from a solid, to a liquid, and then goes to a vapor, but when it condenses it seems to go straight to a solid. Why is
that?
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Sulaiman
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Quote: Originally posted by Yttrium2  | | When moth is smoked it goes from a solid, to a liquid, and then goes to a vapor, but when it condenses it seems to go straight to a solid. Why is
that? |
Please do not smoke moths, the scales make you cough.
I've had a play with the most famous subliming substance - iodine.
When heated gently iodine melts then vapourises,
on contact with a cold surface the vapour appears to instantly solidify.
I suspect that it actually rapidly goes via a liquid phase before crystalising,
with the miniscule quantity of heat being dispersed very rapidly.
If there were not a transient liquid phase I'd expect a more homogenous layer of 'dust', not shiny crystals.
I await condemnation 
CAUTION : Hobby Chemist, not Professional or even Amateur
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Yttrium2
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What happens when you hit it with a blow torch?
You lost me with the condemnation thingy
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Sulaiman
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Condemnation for herecy ... I'm saying that iodine does not sublime at atmospheric pressure 
If you heat rapidly (e.g. with a gas torch) then the iodine appears to sublime,
the liquefaction to evaporation phase would be so transient that it would appear instantaneous.
... I guess.
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fusso
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Nilered's vid about this myth:
https://www.youtube.com/watch?v=dPIaEWd8zf4
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Metacelsus
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Iodine can still sublime at atmospheric pressure and temperatures below its melting point, just as water can evaporate at atmospheric pressure and
temperatures below its boiling point.
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Yttrium2
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What again causes water to evaporate below it's boiling point?
I've never seen iodine heated with a blow torch. My guess would be there would be a lot of purple clouds!
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Pyro_cat
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| Quote: Originally posted by Yttrium2 | What again causes water to evaporate below it's boiling point?
I've never seen iodine heated with a blow torch. My guess would be there would be a lot of purple clouds!
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I do know water gets cold when it evaporates, they say the warmer molecules go first leaving the cooler ones behind.
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Ubya
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the water molecules have different energies, the avarage is the temperature you can measure, this means that there could be molecules with a kinetic
energy equivalent of one at 100°C, so it evaporates if it is on the water-air boundry. water molecules can gain-loose energy by inelastic collisions
with each other.
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feel free to correct my grammar, or any mistakes i make
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SWIM
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There may be some destructive distillation going on there as well.
If the condensate has a significant percentage of decomposition products and polymerized gunk it may set up quickly.
Is the condensate white/clear, or yellow/brown?
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