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Q & A: water temperatures

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Most recent answer: 04/17/2017
Is it true that water (steam and ice) can not get hotter than 212 degrees and colder than 32 degrees?
- Tommy
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.)

(published on 10/22/2007)

Follow-Up #1: boiling and superheating

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
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 10/22/2007)

Follow-Up #2: superheating?

OK, but why then does liquid water open to the atmosphere continue to boil for a few moments after the heat source is removed? Is it just due to residual heat
- Andy (age 68)

The water can be somewhat superheated, as we mentioned. Also, by the time the water is boiling the pot will be hotter than 212°F, so heat from it flows in to boil some more water. 

Mike W.

(published on 04/17/2017)

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