on 6/30/02 9:06 PM, Mark Ross at markr13_at_comcast.net wrote:
>
>>
>> somewhere near the temporal coordinates of 6/29/02 10:07 PM, the entity
>> known as Mark Ross transmitted the following from markr13_at_comcast.net:
>>
>>> In the example of water (solute) in air (solvent), the amount maximum
>>> amount of water that can be held at a given temperature and pressure is
>>> called 100% relative humidity. It is not possible to hold more than that
>>> as the air is saturated with water in this state.
>>
>> I think that if we want to be truly correct, air is not a solvent and water
>> is not a solute. Humidity has to do with thermodynamics and phase changes
>> and isn't really chemistry in the way that term is generally used.
>>
>> - Eric.
>
> Why not? If water is in a gas state (dissolved) in air, it still obeys
> the same PV=nRT gas law and will behave much like a solid dissolved in a
> liquid whereby the solid is now solvated and is liquid-like in behavior.
> Thermodynamics will play the same role for a liquid-solid solution or two
> gases. The degree of interaction (thermodynamics) and the temperature
> (kinetics) will determine what happens at a given P and T.
>
>
Because dissolving, IIRC, occurs because water (for example) is a polar
molecule. That is, the solvent CHEMICALLY aids in some way the dissolving
of the solute (i.e., by molecular attraction). The N2 and O2 of the
atmosphere doesn't participate in any such chemical fashion in the
evaporation of the water. It participates thermodynamically, providing a
pressure and temperature environment conducive to the maintenance of water
vapor in the air.
- Eric.
--Eric Strobel (fyzycyst_at_NOSPAM^mailaps.org)
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