At 10:31 AM 3/30/5, Stephen A. Lawrence wrote: >>>The vapor molecule is >>>stopped when it strikes the liquid surface of a drop. In the process the >>>kinetic energy of the vapor molecule is converted to binding energy in the >>>drop. >>> >But this is, like, backwards, isn't it? You _gain_ kinetic energy when >the molecules join up, you don't lose it! Otherwise sweating, which >runs the process backwards, would make you hotter.
Yes, this is the standard version of things. The kinetic energy of the inelastic collision of molecule-drop-combining is converted to heat. The energy of the hydrogen bonding adds to that initial kinetic energy but then is converted to heat by the inelastic collision and bonding. When sweating, only the most energetic molecules can break the surface tension, thus the molecules remaining end up with reduced net temperature. Seems right to me. Regards, Horace Heffner
