Freezing Point of Water


by klimatos
Tags: freezing, freezing point, icing nucleii, point, water
klimatos
klimatos is offline
#19
Dec1-13, 12:29 PM
P: 403
Quote Quote by fluidistic View Post
I agree with russ watters when he says that the water, despite freezing at lower than 0C temperatures, will reach a temperature of 0C almost instantly after freezing.
I do not dispute this. This is explained by the release of the enthalpy of freezing (what used to be called "latent heat"). I note that you agree that (in ordinary English) water freezes at temperatures lower than 0C and at temperatures higher than 0C.

When a mass of rising air containing water droplets at temperatures approaching -40C freezes to become a mass of rising air containing ice crystals at temperatures approaching -42C, I do not think that I am misleading my students in telling them that many cloud droplets freeze at around -40C.

By the way, since the triple point of water is 0.01C and not 0C, shouldn't we be using the former as the freezing point and not the latter?
klimatos
klimatos is offline
#20
Dec1-13, 12:42 PM
P: 403
Quote Quote by 256bits View Post
Plant tissue - Are we talking about why you have to bring your tomatoes indoors on a calm clear night where the air temperature can fall to somewhere in the vicinity of 4C. The plants radiate out to space and the air temperature is too low to supply enough heat via conduction to prevent freezing.
Are you saying that tomatoes are such effective radiators of EM that this radiation drops the temperature of the tomato below the temperature of the ambient air? I don't think so.

Clathrates - that is a different ice structure from that of what we consider where the melting point of normal ice at 0C.
The ice in clathrate lattices is chemically identical to ordinary ice. It is H2O. Yet, it is a solid at temperatures above 0C.
Yanick
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#21
Dec1-13, 01:14 PM
P: 344
Quote Quote by klimatos View Post
The ice in clathrate lattices is chemically identical to ordinary ice. It is H2O. Yet, it is a solid at temperatures above 0C.
Sorry that is wrong, clathrates are not pure compounds and their physical properties do not constitute proof that our determination of the freezing point of pure water is wrong.

http://en.m.wikipedia.org/wiki/Clathrate_compound

http://en.m.wikipedia.org/wiki/Clathrate_hydrate
russ_watters
russ_watters is offline
#22
Dec1-13, 01:58 PM
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