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Q & A: Water in a Vacuum

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Most recent answer: 06/26/2015
Q:
What is the reaction of water in a high vacuum chamber?
- Daniel Garcia (age 12)
Belen jr high, Belen, NM, USA
A:
Dear Daniel,

We all know that if you heat water up, it will boil. What you may not know is that the temperature at which water (or any liquid) will boil depends on the atmospheric pressure.
Water actually boils at a lower temperature if the pressure around it is lowered. This is why if you go to a high altitude location (like many parts of New Mexico), where the atmospheric pressure is lower, water will boil at slightly less than 100 degrees C.

In a vacuum chamber, the pressure can be extremely low. So low, in fact, that water can actually boil at room temperature.

So, if you put some water in a high-vacuum chamber you will see it boil. (Then, with all that water vapor around, it won't be a high vacuum anymore!)

(published on 10/22/2007)

Follow-Up #1: cooking with cold water vapor?

Q:
Dear Sir, As the water starts boiling in a vacuum chamber , suppose we try to cook vegetables added to water in the vacuum chamber and vacuum pressured steam is supplied to this vacuum chamber , will it cook the vegetable.Kindly reply thanking youregardspruthivi
- pruthivi (age 43)
Bangalore , Karnataka, INDIA
A:

No, the water vapor in this case would be cold, so it wouldn't cook anything.

Mike W.


(published on 06/26/2015)

Follow-up on this answer.