MadSci Network: Chemistry |
Actually liquid or solid water evaporates at all temperatures. As long as there is enough kinetic energy for a water molecule to escape the intermolecular forces water evaporates. You can do a neat little qualitative experiment by putting an ice cube in a no-frost freezer and watch what happens (it sublimes). So to answer your question there is no particular temperature that evaporation starts and stops. Absolute zero is usually defined as a cease in all atomic motion. This is incorrect (or plain wrong if you want to use less polite language). There still is translational motion in the atoms. A better definition is: absolute zero is the temperature where no further energy may be extracted from the system. As you approach absolute zero you still have evaporation(1) but at absolute zero I don't know (nor have I found any information, yet). You could do a thought experiment given the definition of absolute zero and the requirements for evaporation. Then work out the answer on paper. (1) The evaporation rate, free energy, and entropy of amorphous water at 150 K Speedy et. al. The Journal of Chemical Physics -- July 1, 1996 -- Volume 105, Issue 1, pp. 240-244
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