Phase transition due to pressure © Siemens Stiftung 2021 CC BY-SA 4.0 international

Phase transition due to pressure


The state of a substance depends not only on the temperature but also on the pressure. An example of this is skating on ice.

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Ice skaters concentrate their body weight on a very small surface (2 thin blades). The resulting pressure (= force per surface area) liquefies the ice of the top layer. At microscopic level, this means that the water molecules are separated from their atomic binding partners inside the ice. The resulting thin film of water enables the skater to glide over the ice. The simulation shows this effect.
The whole process is augmented by a temperature effect: The sliding friction of the blades on the ice results in a very small amount of heating, which allows the ice to melt even more readily.

Information and ideas:
Ice researchers still do not always agree absolutely in which cases pressure is the dominant effect when skating on ice and in which cases friction. Scientific studies are still being carried out on this subject.
Assignment: Students should explain the melting process due to pressure using the p-T diagram.
There are no other media directly related to this file.
Chemistry; Physics
Grade 7 to 9; Grade 10 to 13
Middle/high school
Molecule; State of aggregation; Molecular structure (chemistry); Phase transition; State of aggregation
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© Siemens Stiftung 2021
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