Solid Nitrogen-Liquid nitrogen in a vacuum chamber

Solid nitrogen in vacuum chamber

With the boiling point of 321 degrees Fahrenheit below zero, few things are colder than liquid nitrogen. But what happens if we put liquid nitrogen in a vacuum chamber? As the vacuum pump lowers the pressure in the chamber, it also decreases the boiling point of any liquid within the chamber.

As a result our pool with liquid nitrogen is now superheated above its new boiling point and so it boils with greater vigour. Boiling faster increases evaporation of the liquid nitrogen and this active evaporation cools the liquid in the same way that evaporating sweat cools our body. So as more vapour boils away the liquid left behind gets colder. Eventually the remaining liquid nitrogen becomes so cold that it turns into a glassy solid. Solid nitrogen is something that few people have ever seen.

The solid nitrogen is colder than 346 degrees Fahrenheit below zero, but when the evaporation has stopped the residual heat the metal inside the vacuum chamber begins to warm the solid nitrogen. Eventually it will melt but not before something remarkable happens. The randomly frozen nitrogen atoms want to organize themselves into a hexagonal lattice that is more tightly packed.

Solid Nitrogen Slow Motion

In the second video, we have used our high-speed camera to reveal the nucleation and spreading chain reaction of nitrogen atom snapping into their new positions. The force of rearrangement is powerful enough to scatter flaky bits of solid nitrogen. What you can see in slow motion video are infinitesimal atomic movements made visible to the naked eye.

Solid Nitrogen-Liquid nitrogen in a vacuum chamber on 2015-07-15 rated 5.0 of 5

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