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What would happen to an Ice cube on the moon?

As atmospheric pressure decreases the boiling point follows. But at absolute zero, all things will 'freeze' so become solid. So would said ice cube: 1) Evaporate because of the low pressure, or 2) Stay solid, because of the temperature?
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Categories: Our universe.

Tags: physics, Space, ice, chemistry, pressure.

 

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Jon-Richfield says:

It would evaporate as you suggest, but not instantly. That is the basis of "freeze drying" or lyophilisation. The drying speed is limited by the rate of energy supply; if you were to keep your ice in the shadow of Pluto where there is little heat and little radiant energy, it would evaporate extremely slowly. In fact, a large "wet" comet (containing lots of water in the form of ice only, and very dry indeed) might take billions of years to lose all its water and even all its ammonia.

Absolute zero simply does not nearly get a look-in, except possibly with hydrogen or helium. But I doubt that we have any place outside a lab in our solar system where they liquefy.

The rate of evaporation generally balances the rate of energy input and the vapour pressure (which in space is negligible). The faster a substance evaporates, the more it cools, until the cooling brings it down to a temperature where it evaporates at just the rate to maintain a steady temperature. On the moon it would evaporate rapidly in the sun, but slowly during the lunar night. Impurities in the water, such as dissolved salts, would settle out as a fine powder.

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Tags: physics, Space, ice, chemistry, pressure.

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posted on 2010-12-17 19:48:40 | Report abuse


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Georg says:

But at absolute zero, all things will 'freeze' so become solid.

 

All things will freeze well above absolute zero, exept

helium, but  helium  will not freeze at all!

Nevertheless my impression is, You believe that "frozen"

things do not evaporate?

Regarding temperatures on the moon, here are very deep thoughs

by Christian Morgenstern on this topic:

 

Der Mondberg-Uhu hat ein Bein,

sein linkes Bein, im Sonnenschein.

Das rechte Bein jedoch des Vogels

bewohnt das Schattenreich des Kogels.

Bis hundertfunfzig Grad im Licht

gibt Herschel ihm (zwar Langley nicht),

im Dustern andrerseits desgleichen

dasselbe mit dem Minuszeichen.

 

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posted on 2010-12-20 18:08:28 | Report abuse

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Jon-Richfield says:

Morgenstern was a respected comic poet, flowing and urbane, and I have seen some of his  work translated into English, but this one is new to me.

Mind you, if I understand the verse fully, he was pretty cheerful about his lunar ornithology!  ;-)

And incidentally, yes, you were right about the rum & coke; the head of beer is indeed the layer of froth on top.

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posted on 2010-12-20 19:04:12 | Report abuse


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