Fugacity: It is derived from Latin, expressed as fleetness or escaping ...

When A=B
2
ln Ax ,
1
2
ln Ax
2
2
1
The above equations are known as Margules suffix equation.
Wilson Equation:
Wilson proposed the following equation for activity coefficients in binary solution
12
21
ln
1 lnx1
12
x2
x2
x1
12
x2
21x1
x2
ln
2
ln
12
21
x2 21x1
x1
x1
12
x2
21x1
x2
Wilson equation have two adjustable parameters 12
component molar volumes.
12
21
V2 11 2
12
V
1
V
12
exp
RT
12
exp
RT
V
V
1
V
V
a
exp
RT
V1 22 1
21
2
2
a
exp
RT
V1 and V2 – molar volumes of pure liquids
- Energies of interaction between molecule
and 21
. These are related to pure
Wilson equation suffers main disadvantages which is not suitable for maxima or minima
on ln versus x curves.
Consistency of VLE data
Gibbs duhem equation in terms of thermal consistency
x
1
d ln
dx
1
1
( 1
d ln
x1)
dx
1
2
0
Plot of logarithmic activity coefficients Vs x1 of component in binary solution