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VAPOUR LIQUID

 EQUILIBRIUM

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Dalton’s law

Ptotal = p1+ p2Where,

Ptotal  -Total pressure p1 ,p2 -Partial pressure of component.

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Composition of liquid phas !

x1= p1/ p10

  =  partial pressure of component /vapour pressure of pure component

Composition in aseous phase !" 1= p1/ P

  =  partial pressure of component /total pressure#aoult$s la% &ecomes

"iP=xiPisat  'i=1,2,()..n*

Where!

"i = apor-phase mole fraction.xi = iui-phase mole fraction.

Pi = apor pressure of pure species i at the T of the s"stem.

"i P = Partial pressure of species i.

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VLE "# Modifid Raoult’s Law

"i P = xi i Pisat ' i= 1,2,)..,*

Where

i = ctivit" coefficient.

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Equili"$ium Dia%$amVapo$ &omposition is d$awn a%ainst liquid &omp at

&onstant p$ssu$' Vapou$ is alwa#s $i&h in mo$(olatil &omponnt th &u$( lis a"o( th dia%onal

lin'

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Eff&t of (a$#in% p$ssu$ on quili"$ium

dia%$am

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P)*)# Dia%$am

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uacit" coefficient '  ) :ɸ uacit" coefficient is efine as the ratio of fuacit"

of component to its pressure.

=f/P ɸ

- 3s the measure of non ieal &ehavior of the as.ɸ

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A&ti(it# &offi&int quations

  Wohl$s three suffix euation

  4arules euation

  an laar euation

  Wilson euation

   on ranom t%o liui '#T*euation

  5niversal uasi 6chemical '5375C*euation

  5niversal functional activit" coefficient '53C*metho

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Consistn tst fo$ VLE data

  5sin slope of ln curves

  5sin ata at mi point

  #elich 68ister metho

  5sin the coexistence euation

  5sin partial pressure ata

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Thank You