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Pressure Relation to State

  1. Jul 8, 2009 #1
    I imagine everyone here is familiar with the classic demonstration of making water boil at room temperature using a vaccuum pump. Since lowering pressure changes the state from liquid to gas, can raising the temperature cause it to freeze? I know some about the difference in amounts of pressure it takes to undergo the change from liquid to gas and from liquid to solid, but is this even theoretically possible? Obviously it's not going to happen in a high school lab, but I was just wondering if there is a pressure at which water will freeze at room temperature.
  2. jcsd
  3. Jul 9, 2009 #2
    I'm not that knowledge on chemistry, but since I believe a liquid, solid, and gas are determined by how dense their molecules are, that under significant pressure that molecules would be packed so tightly in order to call it a solid.
  4. Jul 9, 2009 #3


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    I assume you mean pressure here. Yes, http://www.lsbu.ac.uk/water/images/phase.gif" [Broken].
    Last edited by a moderator: May 4, 2017
  5. Jul 10, 2009 #4


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    That's not exactly true. Lowering pressure you lower boiling point temperature - but it is not enough to vaporize the liquid. For that you still need to add enough heat to the system (enthalpy of vaporization). Boiling in the experiment you have described is possible thanks to water lowering its temperature, and soon stops in the lack of external heating.
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