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Physics, Astronomy & Cosmology / Re: Is there a net heat exchange between water and ice at 0 degree C?
« on: 03/06/2020 10:29:42 »Do you think that emissivity has no effect here?Certainly not much effect.
Ice dosn't emit much IR, and nor does cold water.
The emissivity and absorption are identical at any wavelength.
https://en.wikipedia.org/wiki/Kirchhoff%27s_law_of_thermal_radiation
And imagine that I had some water, and some ice (Initially at 0 C) enclosed in a reflector so that any radiation they emitted was contained until it was absorbed again.
They must both stay at 0C.
If they didn't, I could run a heat engine from the difference and get free energy.
On the other hand, the water and ice are in contact, so thermal conductivity is a good pathway for heat transfer- if there was going to be any.
Do you mean they exchange phase? How is the isotope tracing done?Freeze some tritium labeled water.
Put the radiolabeled ice in normal water at 0C.
Wait, and then measure the activity of the water phase.
It slowly becomes active.
The same thing can be used to show that "insoluble" solids exchance ions with the solution they arein.
By definition in your question, at 0c everything is the same temperature. Unless one changes temperature no. No ice can form or melt without the exchange of energy in the form of kinetic energy of the molecules. Non nil nein nada negagive niet nix.Fluctuations.
The temperature is a property of the ensemble of molecules, but individual molecules are allowed to have different KE from the average.
So the exchange is possible.
Incidentally, after someone has said the exchange does, in fact, take place, it's not wise to categorically say that it can't.
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