deadrush - 30-10-2024 at 18:58
So I have a pressurized container of dimethyl ether. I used the spraying mechanism it came with which essentially trapped it in a small area
surrounded by seemingly ordinary plastic. To my disbelief, I saw a liquid pool on the side after spraying. Not only that, but it remained a liquid
without boiling for quite some time. Now this was not a space capable of maintaining high pressures.
The BP is like -31C I believe, so what happens? I once froze a can of butane and sprayed the liquid into a soda bottle. I fail to see how at stp it
could even be a liquid for any amount of time.
just guessing
Sulaiman - 31-10-2024 at 00:20
Plastics are very poor thermal conductors = good thermal insulators
so
I can imagine the plastic in contact with liquid being at the BP of the liquid,
to evaporate the liquid to gas the heat of evaporation energy has to flow through the plastic....slowly.
So the evaporation rate could be quite slow, even with an STP atmosphere,
because the gas in contact with the liquid will be near the BP
and the outside of the plastic has to get heat from it's surroundings.
Same principle as a Dewar of liquefied gas.
unionised - 31-10-2024 at 03:09
A liquid will stay liquid until it gets enough latent heat from somewhere to evaporate it.
That might be heat from the liquid itself (in which case it will cool) or it might be from the surroundings.
(Or it might be a bit weird and freeze- like CO2 does.)
You say you " fail to see how at stp it could even be a liquid for any amount of time."
The simple answer is that it is no longer at stp. It is much colder.
[Edited on 31-10-24 by unionised]