• Question: If you have a strong enough press, is it possible to change water to ice by just putting it in a container and squashing it with machines?

    Asked by allanacquah to Ben, Dave, Ed, Sam, Susana on 21 Jun 2013.
    • Photo: Sam Horrell

      Sam Horrell answered on 21 Jun 2013:

      There are a couple of different crystal forms of ice because of the various ways you can arrange the molecules. Different arrangements become ice at different pressures and temperatures.

      Fot the most crystal forms no, beacuse water has this strange property of expanding when it becomes solid instead of becoming more compact like other materials.

      It is possible to form some forms of ice with pressure but the pressures required are staggeringly high at around 1 megabar. That’s 1000 times the pressure of Earths atmosphere. We have machines that are able to reach 2.1 megabars so yes you could create ice from water with one of those. If it would stay solid when you dropped the pressure is unlikely.

    • Photo: Susana Teixeira

      Susana Teixeira answered on 26 Jun 2013:

      It is possible, yes, if you apply just above 1GPa of pressure (9869atm!) at a temperature around 20 degrees Celsius.
      The ice we commonly know and put on our drinks is actually a crystal (hexagonal symmetry) and as it so happens it is less dense than water, so it will need more space and if it formed it would blow up your container.
      Not to worry though, if you increased pressure in your container but kept the temperature, then you’d get a tetragonal type of ice which is even more dense than liquid water so you’d be fine 😉

    • Photo: David Briggs

      David Briggs answered on 26 Jun 2013:

      Yes it is – Sam and Susana have the answers!

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