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Q & A: water thermodynamics

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Most recent answer: 04/13/2011
Q:
Hey, I have a question that relates to thermodynamics: Suppose I have a glass of water, the glass and the water remain 20 degrees celsius (let's say a demon keeps them that way), the glass is in an infinite space and the space's temperature is 70 degrees celsius and it remains that way (by the same demon perhaps?), what will happen to the water? I was asked this question so I don't know if the space is vacuum or somekind of gas but if you can't consider both options. What I thought is that the water stays in place because the system is in thermodynamic equilibrium (if the temperatures stays the same, no?) Thanks!
- Daniel (age 21)
Israel
A:
There's a couple of parts to that question. The first would be that it's kind of odd that the space could be at 70C and the water at 20C, since energy would always flow from the hot to the cold region. But maybe that demon has a power source and a little heat pump or something to keep these out of equilibrium.

It doesn't much matter here if the space starts off as a vacuum (with only electromagnetic radiation) or as having some gas (other than water vapor itself) in it. Either way, unless the demon is also busy pumping water molecules back into the glass, the water in the glass will all evaporate.

Mike W.

(published on 04/11/2011)

Follow-Up #1: welcome

Q:
Thanks!
- Daniel (age 21)
Israel
A:
mw

(published on 04/13/2011)

Follow-up on this answer.