What happens to water in a high vacuum?

Longzhong vacuum water


As you all know, the boiling point of water is related to the atmospheric pressure. The lower the pressure, the lower the boiling point; if you are on a plateau with a higher altitude, it may boil over 70 degrees!
Have you ever thought about what would happen if water was in a high vacuum?


In a vacuum state, the air pressure of the environment where water is located is almost 0. At this time, the boiling point of water is extremely low, and it can reach a state of boiling at room temperature. However, in fact, the state of boiling is one of the ways of "gasification" of liquids. Sheung Shui is "evaporating", it just "looks" like boiling.

Since changes in air pressure can affect the boiling point of water, can it also affect the freezing point? If the air pressure is continuously lowered, will the water become solid ice when the environment is close to absolute vacuum?

Pressure does affect the freezing point of water.
When the pressure intensity is below a certain value, no matter what the temperature is, water will not exist in liquid form. Therefore, the water in a vacuum environment will first appear in the form of boiling, and the gasification process needs to absorb heat. In other words, the evaporation of water will take away part of the heat. When the temperature is low to a certain extent, the water will form solid ice.


*Supplementary Instructions*
So will ice cubes melt in a vacuum?

The answer is: it won't melt, but it will sublimate.
The definition of melting refers to the process of turning a solid into a liquid; sublimation refers to the process of turning a solid into a gas without going through a liquid. There is no medium that can transmit energy in the environment in the physical vacuum. It was mentioned just now that the water in the vacuum will be directly vaporized, so the ice cubes will not melt into the existence of liquid water in the vacuum environment, but will be directly sublimated into gas (Like dry ice smoking)


Automatic control design planner ─ Longzhong Enterprise
Address: 7F-1, No. 986, Zhongzheng Road, Yongkang District, Tainan City
Telephone: 06-243-7822

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