6 replies to this topic

[Dumpmeadrenaline]

Given water in a pot in an open system, within the pot of water, water molecules are in constant motion, some of which will escape from the liquid into air as vapor. So can vapor pressure be interpreted as the force exerted by the water molecules escaping over the area of the liquid surface?

Edited by Dumpmeadrenaline, 06 December 2021 - 08:40 PM.

[latexman]

In an open system, the force exerted over the area of the liquid surface is atmospheric pressure. Rethink your interpretation in a closed system.

[Dumpmeadrenaline]

Pulled down by gravity the air above the water in the pot creates pressure (collisions of air molecules against the water surface).However, at the same time water molecules exert pressure when they leave the liquid surface. Do we call the opposing collisions against the air molecules vapor pressure. 

[Dumpmeadrenaline]

1) Considering an open system and before reaching the boiling point of water, will the amount of water in the pot decrease to a constant as energetic water molecules escape the surface?

[latexman]

Vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases at a given temperature in a closed system.

[Dumpmeadrenaline]

1) Why can't equilibrium be achieved in an open system?

In an open pot, vapor water molecules are continuously escaping into the atmosphere and at the same some of them collide with the air molecules above the pot and condense back into liquid water molecules. Do you imply that the rates of condensation and evaporation are never equal and are fluctuating with time?

[horatorres]

Vapor pressure is considered into an equilibrium condition at a closed system..

 

It is not feasible in open systems like the atmosfer, talk about vapor pressure

 

Horacio