Vapor Pressure

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Vapor pressure|vapor pressure of water

Vapor pressure|vapor pressure of water

When a liquid is in contact with its vapor two opposing processes are in operation. The process of vaporization tends to change the liquid to the gaseous state. The process of condensation tends to change the vapor the vapor which is formed by vaporization back into the liquid state. These two opposing processes continue till the pressure of the vapor ultimately reaches such a value that the rate of condensation equals the rate of vaporization and an equilibrium is established.
                  The pressure exerted by the vapor at equilibrium conditions is termed as the vapor pressure of the liquid.
The equilibrium vapor pressure is in no way dependent on the quantity of liquid and vapor, as long as a free liquid surface is present.
           The effect of temperature on the vapor pressure of a liquid is given by the Clausius-Clapeyron equation
                clip image002

Where  = molar latent heat of vaporization. It is assumed in the development of Eq.  that
1.      The vapor obeys the perfect gas law.
2.      The volume of the condensed phase is negligible in comparison with that of an equivalent amount of vapor, and
3.      The latent heat of vaporization is independent of temperature.
The results are accurate only limited ranges of temperature.
Vapour pressure data for many compounds have been correlated by using the Antoine equation.
                           In p0=A-B/T+C,Pa                                                                   

Representative values of the constants A,B and C are given in the following table.

 Component            Range Of T,K          A                             B                       C
Acetone                       241-350          21.5439              2940.46             -35.93
Ammonia                     179-261          21.8407              2132.50             -32.98
Benzene                      280-377           20.7934              2788.51            -52.36




Some useful information about vapor pressure are as following .

  • vapor pressure exampleVapor presure of water is 28 mmhg @ 28 DegC
  • vapor pressure and boiling point→vapor pressure and boiling point are related to each other , boiling point is depends on vapor pressure 
  • vapor pressure and inter molecular forces →vapor pressure is depends on bonding on molcules , double bond ,single bond 
  • what affects vapor pressure→read above article 
  • vapor pressure of water→28 mmhg @ 28 DegC
  • vapor pressure for dummies→
  • vapor pressure of water in kpa→3.78 kpa @ 28 DegC
  • vapor pressure of water psi→0.54 psi 28 DegC
  • vapor pressure of water calculator→NA
  • vapor pressure of water definition→the pressure of water in contact with liquid is vapor pressure
  • vapor pressure of water at 293 k→ 25 mmhg
  • vapor pressure of water from curve in mmhg→25 
  • vapour pressure of water at 298 k→26 mmhg
  • vapor pressure of water at 20 c in kpa→22 mmhg
  • partial pressure of water at 26 c→
  • antoine equation→see article 
  • saturation vapor pressure→
  • the vapor pressure of water at 80°c is→
  • vapor pressure data→
  • saturation vapor pressure table→

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