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Q & A: water temperatures

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Q:
Is it true that water (steam and ice) can not get hotter than 212 degrees and colder than 32 degrees?
- Tommy
Seattle
A:
It is not true that water can only get up to 212 degrees and as cold as 32 degrees. After water changes from a liquid to a gas (at 212 degrees Fahrenheit) it can actually heat up much hotter than that. In the gas form, water molecules are spread out and have a lot of room to move and get much hotter than the other two phases (liquid and ice).
And water freezes at 32 degrees Fahrenheit. But it can actually get colder than that, all the way toward what we call absolute zero. This value is equivalent to about -459 degrees Fahrenheit. This is when the water molecules are basically not moving. Hope this answers your question!

(but see below- if the question concerns liquid water, it becomes unstable outside the temperature range mentioned, at atmospheric pressure. Mike W.)

(republished on 07/27/06)

Follow-Up #1: boiling and superheating

Q:
but what about the water itself water will only get to 212 then turn to a gas unless water is in a pressure cooker the water cannot get above 212, or am i wrong?
- Dan
wapakoneta,oh,us
A:
You’re sort of right. Above 212°F at standard pressure, liquid water is unstable. It will evaporate very rapidly from the surface. If the temperature is held constant (which requires some heat input, since evaporation cools things) the liquid will all evaporate.
If the temperature is much above 212°F, the water will boil. That means that it won’t just evaporate from the surface but will form vapor bubbles, which then grow, inside the liquid itself. If the water has very few dust flecks etc. in it, this boiling process doesn’t happen until the temperature is significantly above 212°F, so you can temporarily have liquid water (called ’superheated’) above that boiling point. If there are good nucleation sites for the boiling to start (teflon surfaces are a good example) you can’t get much superheating.

you might search this site and others using the key word ’superheated’.

Mike W.

Lee H

(published on 03/03/07)

Follow-up on this answer.