The maximum vapor pressure is the pressure at which the vapor is saturated and therefore no additional liquid will evaporate, since the same amount of liquid condenses again (dynamic equilibrium). I am told that the maximum vapor pressure will increase with an increase in temperature. However, I don’t understand this. After all, when the temperature rises, more particles (eg molecules) will evaporate, but at the same time more particles will end up in the vapor, so that more particles will condense because they end up back in the liquid via collisions?
Answer
It is correct that in a saturated vapor as many particles leave the vapor phase (condense) as they enter (evaporate). If the liquid/vapor has a higher temperature, the particles will have more kinetic energy and will collide more violently, also with the walls. This results in a higher pressure, just like with the gas laws. In addition, due to the higher temperature, more particles leave the liquid phase (evaporate). These particles will cluster less easily due to their greater speed. The particles in a saturated vapor with a higher temperature are therefore more numerous and they move more violently: this results in an increased pressure.
Answered by
Wim Verreycken
Physics/Natural Sciences Author handbook Physics Xpert
http://www.thomasmore.be
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