medium difficulty physics question

[gasblaster]

Strong sealed container full of pure water ice. As the ice melts, its reducing volume creates a vacuum. As something needs to fill the vacuum, I assume this is water vapour - so, does the melting icewater 'boil' to produce the vapour?

[JoolzB]

gasblaster said:

Strong sealed container full of pure water ice. As the ice melts, its reducing volume creates a vacuum. As something needs to fill the vacuum, I assume this is water vapour - so, does the melting icewater 'boil' to produce the vapour?

If something needed to fill the vacuum it wouldn't be a vacuum?

[dogwatch]

Nature abhors a vacuum but can't always do anything about it - or there wouldn't be any Thermos flasks.

[cazzer]

Thats why nature's carpets are so dusty.

[danhay]

It would depend on the temperature of the vessel after the ice has melted. You can boil water at room temperature if you lower the pressure enough. I think that a small part of the water would vapourise and reduce the vacuum slightly but not eliminate it completely.

[ATG]

gasblaster said:

Strong sealed container full of pure water ice. As the ice melts, its reducing volume creates a vacuum. As something needs to fill the vacuum, I assume this is water vapour - so, does the melting icewater 'boil' to produce the vapour?

Yes. The pressure inside the vessel will remain way below normal atmospheric pressure, but a certain amount of water will evaporate to produce a thin vapour in the container. The same would happen if you put an ice cube in a pressure vessel and pumped out all the air (i.e. the state of some of the water would go straight from solid to gas).

Here you go:
http://hyperphysics.phy-astr.gsu.edu/
The pressure in the "not-quite-vacuum" is determined by the saturation vapour density of water. There's a table at the top of the page. Assuming your vessel is at 0 centigrade, the pressure in the vessel above the ice will be 4.58mm of mercury which is 0.006 atmospheres.

>> Edited by ATG on Wednesday 22 February 19:37

[Size Nine Elm]

ATG said:

Assuming your vessel is at 0 centigrade, the pressure in the vessel above the ice will be 4.58mm of mercury which is 0.006 atmospheres.

Bugger. Here we go with a perfectly good question with which to propose wild and untestable theories of the universe, with planes taking off whilst stationary in clouds of water vapour, and you go and give a sensible scientific answer and remove all these delightful hypotheses.

This is PH, you know.

[ATG]

Size Nine Elm said:

ATG said: Assuming your vessel is at 0 centigrade, the pressure in the vessel above the ice will be 4.58mm of mercury which is 0.006 atmospheres. Bugger. Here we go with a perfectly good question with which to propose wild and untestable theories of the universe, with planes taking off whilst stationary in clouds of water vapour, and you go and give a sensible scientific answer and remove all these delightful hypotheses. This is PH, you know.

Sorry, you're right. Let's see now ... 'kay ... "the water wouldn't boil much because Corvettes (which means "toilet" in Burma) can't go round corners unless they're on trailers and Speed 6 engines spread radoiactive waste in primary schools. And the government likes it that way and photos it with speed cameras."

[John_S4x4]

gasblaster said:

Strong sealed MGF radiator full of pure water ice. As the ice melts, its reducing volume creates a vacuum. As something needs to fill the vacuum, I assume this is water vapour - so, does the melting icewater 'boil' to produce the failed headgasket?