Vapor Pressure

[HowAboutDAT]

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If you have a closed container and increase the volume of a liquid inside it, will the vapor pressure increase, decrease or remain the same?

What if you decrease the volume of space above the liquid?

Thanks!

 

[206127]

Increasing the volume of liquid in a container has no effect on vapor pressure. For example, a sealed rectangular can that is taller than it is wide and half-filled with a liquid will develop a vapor pressure. If the cap is removed and more liquid is added to the can, the liquid volume increases and forces vapor from the can into the air. Once the cap is replaced, the amount of vapor above the liquid decreases such that the vapor concentration, or number of particles per unit volume, is the same as before. The number of collisions per unit area does not change. Therefore, the equilibrium vapor pressure remains unchanged.

 

[adizzle87]

Too add to that it is my understanding that only temperature will affect vapor pressure as well.

 

[206127]

Too add to that it is my understanding that only temperature will affect vapor pressure as well.

👍 I agree but wasn't 100% sure...

 

[basarachobits]

Is the closed container equivalent to a closed system. If so, I don't think material can be exchanged, so the volume of the liquid should not be increased.

 

[HowAboutDAT]

there wasn't a specific question or anything, i was just reading some material and just needed clarification, but thanks guys

 

[doc toothache]

http://www.sensirion.com/pdf/product_information/Introduction_to_Relative_Humidity_E.pdf

 

[HowAboutDAT]

Two other things that can change the vapor pressure are increasing the strength of the intermolecular forces in the liquid, which will decrease vapor pressure, and dissolving a solute in a the liquid, which will also decrease the vapor pressure.