How Does Surface Curvature Affect Saturation Vapour Pressure?

In summary, pressure exerted by a saturated vapour increases with temperature and the curvature of the liquids surface. The pressure is also dependent on the cohesive forces among the molecules.
  • #1
EIRE2003
108
0
The pressure exerted by a saturated vapour depends on the temperature and the curvature of the liquids surface.

Why does it depend on the curvature of the liquids surface?
 
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  • #2
where does the evaporation occur?
 
  • #3
EIRE2003 said:
The pressure exerted by a saturated vapour depends on the temperature and the curvature of the liquids surface.
Why does it depend on the curvature of the liquids surface?

I believe one is referring to 'surface tension', which is a liquid property - the molecules are still in continuous contact. In a two phase system, liquid and vapor, the molcules are evaporating at the liquid vapor interface.

A vapor bubble must expand against a liquid, and it the tension in the liquid (surface tension) which is providing resistance to the bubble expansion. The surface tension is dependent on the cohesive forces among the molecules.
 
  • #4
See "Kelvin equation."
 
  • #5
my first reply was "a drunken post", just to clear up this query further
When pressure is exerted on a liquid, whether through the introduction of an inert gas or by direct porous piston, the vapor pressure increases. Pressure is applied to the liquid, more gases escape.
The relation to surface curvature is in which one considers the variation of the pressure due to surface tension with the curvature of a particular liquid. A droplet of water for instance, experiences an internal pressure as well as an external pressure, along with surface tension, which acts to shrink the droplet, and can be equated with the external pressure. This additional "external pressure" serves to increase the vapor pressure (compared to that of a bulk liquid).
the equation to remember is
[tex]p=p*e^{ \frac{Vm \Delta P}{RT} } [/tex] where the [tex] \Delta P [/tex] pertains to the change in the total pressure experienced by a liquid.
 
  • #6
From Clausius Clapeyron Equation ,
dlnPs/dT=H/RT2,
we can get
lnPs=-H/RT+C,ie,
Ps=exp(-H/RT+C)=Aexp(-H/RT), A=exp(C).

But how can we get A? I don't know.
My answer is right?
 

What is saturation vapour pressure?

Saturation vapour pressure is the maximum amount of water vapor that the air can hold at a given temperature and pressure. It is a measure of the balance between the evaporation of water and the condensation of water vapor in the air.

How is saturation vapour pressure calculated?

Saturation vapour pressure is typically calculated using the Clausius-Clapeyron equation, which takes into account the temperature and energy of the water molecules, as well as the pressure of the surrounding air.

What factors affect saturation vapour pressure?

The main factors that affect saturation vapour pressure are temperature, air pressure, and the presence of other gases in the air. Higher temperatures and lower air pressure can increase the saturation vapour pressure, while the presence of other gases can decrease it.

What is the significance of saturation vapour pressure?

Saturation vapour pressure is an important concept in meteorology, as it helps to determine the likelihood of precipitation and the formation of clouds. It is also used in agriculture to predict the likelihood of plant diseases caused by high humidity levels.

How is saturation vapour pressure related to relative humidity?

Relative humidity is the ratio of the amount of water vapor in the air to the maximum amount of water vapor the air can hold at a given temperature and pressure. Therefore, saturation vapour pressure is directly related to relative humidity, as it is the point at which the air is holding the maximum amount of water vapor possible.

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