At equilibrium no driving force for energy or mass transfer . Equilibrium is the static condition in which no change occur in the macroscopic properties of a system with time
p1=x1.p10 Where, p1-partial pressure of component p10-vapour pressure of pure component x1 -mole fraction of component in liquid phase
Ptotal = p1+ p2 Where, Ptotal -Total pressure p1 ,p2 -Partial pressure of component.
x1= p1/ p10 = partial pressure of component /vapour pressure of pure component
Composition in gaseous phase : y 1 = p 1/ P
= partial pressure of component /total pressure Raoult’s law becomes
yiP=xiPisat (i=1,2,3…..n) Where: yi = Vapor-phase mole fraction. xi = Liquid-phase mole fraction. Pi = Vapor pressure of pure species i at the T of the system. yi P = Partial pressure of species i.
yi P = xi γi Pisat ( i= 1,2,…..,N) Where γi = Activity coefficient.
Fugcity coefficient (ɸ) : Fugacity coefficient is defined as the ratio of fugacity of component to its pressure.
ɸ=f/P ɸ- Is the measure of non ideal behavior of the gas.
Activity(a): It is defined as the fugacity of the existing condition to the standard state fugacity
a=f/ fo Activity coefficient : It measure the extent to which real solution depart from ideality. lnγ₁=bx₂² lnγ₂=bx₁²
Wohl’s three suffix equation Margules equation Van laar equation Wilson equation Non random two liquid (NRTL)equation Universal quasi –chemical (UNIQUAC)equation Universal functional activity coefficient (UNIFAC) method
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