There are several possibe expansions that can be used for the Gibbs excess

energy. One of them is the Redlich-Kister expansion

 

 

gE= x1.x2[A + B(x1 - x2) + C(x1 - x2)2]

 

 

where B=0, but A and C are nonzero. Find expressions for the activity coefficients for the

excess Gibbs energy model in which γ1 is given solely in terms of x2 and the parameters A

and C, and γ2 only in terms of x1, A and C.

Hello, this is really CaptainPanic's field, but I haven't seen him around lately.

Perhaps someone can get him on the batphone?

 

For your information, this site accepts superscript and subscript useful for powers and indices without needing TEX.

 

The toolbar has bold, italic, underline, strikeout, subscript, supercript and some.

 

So I have written out you equation again for the benefit of those who don't realise it has powers in it.

 

[math]\frac{{{G^E}}}{{RT}} = {x_1}{x_2}\left\{ {A + B\left( {{x_1} - {x_2}} \right) + C{{\left( {{x_1} - {x_2}} \right)}^2}} \right\}[/math]

It is useful realise that in a binary system like yours, x₂ = (1-x₁) and to obtain the gammas you need to rearrange the xs and take logs.

 

However we do not do homework for you, but can work with you to help you solve the problem.

 

So please show what working you have so far.

 

A useful reference is

 

Redlich, Kister & Turnquist

Chem Eng. Progr Symp Ser 48(2): 49, 1952.

Edited November 2, 201510 yr by studiot