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Pressure's Effect on State Changes



Melting/Freezing points and Boiling/Condensing points aren't just based on temperature; pressure is also involved. This fact can be observed by having a weighted wire go through a block of ice, as witnessed in this video.

As shown in the video, pressure is also a major factor in determining the melting point of ice. On a molecular level, the molecules under the wire get increased kinetic energy, causing them to become liquid. once the wire passes through that part of the block of ice, the molecules lose the excess energy and refreeze.

The melting/refreezing phenomenon also happens when ice skaters glide on ice. The weight of the person on the skate causes a large force to be exerted on a small amount of ice, melting it, meaning that ice skaters actually skate on water. Once the skater glides over the spot, the the pressure is no longer there, and the water refreezes.

Other effects of pressure on state changes of molecules is the effect of high altitude on boiling points. Places like Denver, Colorado which have lower air pressure than places nearer to sea level cause water to boil at lower than normal temperatures, resulting in a need for adjustments in cooking techniques.

Differences in pressure as well as temperature have an effect on state changes of particles.


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