Solution:
For a binary liquid mixture, the activity coefficient of species $1$ and $2$ are
\begin{align*}
RT \ln \gamma_1 = C (1 – x_1)^2\quad \mbox{and}\quad RT \ln \gamma_2 = C (1 – x_2)^2
\end{align*}
where $C$ is a constant. Please find the expression for Gibbs–energy change of mixing and the criterion of stability.
