How does humidity affect vapor pressure of other chemicals?

[dbooksta]

How does humidity (water vapor pressure) affect the vapor pressure of other chemicals? I'm wondering in particular about evaporation of hydrophobic/immiscible solvents. E.g., does relative humidity affect the evaporation rate of octanol, or the upper limit of octanol that can be held in air (holding temp and pressure constant)?

Is there a general theory of how vapor pressures of different chemicals interact? Any pointers would be appreciated!

[hvacker]

Dalton's Law of partial pressures discribes how each gas behaves as if it occupied the space alone. The total pressure is the sum of the partial pressures.
Maybe a study of this law would find an answer.

[dbooksta]

Well, following some research I should say that this is not trivial chemistry! However based on what I can tell miscibility has little if any relationship to vapor pressure equilibria in mixed gas systems.

Should anyone else come cross this question in the future: http://en.wikipedia.org/wiki/Vapor-liquid_equilibrium seems to have pointers to all the relevant theory....