Freezing point

[sigma]

Accepting all the required conditions, at what temperature does water freeze.

[jake-the-peg]

In which scale?

0˚C by definition or roughly 273˚K

[sigma]

By definition yes but this is the transition point, what is the actual temp. at which it freezes.

[kempie]

It will depend on the presence of nucleators.

Pure water freezes at −42� C rather than at its melting temperature of 0� C if no crystal nuclei, such as dust particles, are present to form an ice nucleus.

http://en.wikipedia.org/wiki/Nucleation
http://en.wikipedia.org/wiki/Supercooling

[wildwood]

Does this mean that frozen water can not be cooler than -42c?

[sigma]

Cheers Kempie