For a concentrated solution of a weak electrolyte ${\mathrm{A}}_{\mathrm{x}} {\mathrm{B}}_{\mathrm{y}}$, the degree of dissociation is given by

For a concentrated solution of a weak electrolyte ${\mathrm{A}}_{\mathrm{x}} {\mathrm{B}}_{\mathrm{y}}$, 

$$\begin{gathered} {\mathrm{A}}_{\mathrm{x}}{\mathrm{B}}_{\mathrm{y}} \rightleftharpoons {\mathrm{xA}}^{\mathrm{y}+}+{\mathrm{yB}}^{\mathrm{x}-} \\ \mathrm{Initial} \mathrm{C} 0 0 \\ \mathrm{At} \mathrm{equilibrium} \mathrm{C}-\mathrm{C}\left(\mathrm{x\alpha }+\mathrm{y\alpha }\right) \mathrm{Cx\alpha } \mathrm{Cy\alpha } \end{gathered}$$

We have

$\begin{array}{l}{\mathrm{K}}_{\mathrm{eq}}=\frac{{\left[{\mathrm{A}}^{\mathrm{y}+}\right]}^{\mathrm{x}}{\left[{\mathrm{B}}^{\mathrm{x}-}\right]}^{\mathrm{y}}}{\left[{\mathrm{A}}_{\mathrm{x}}{\mathrm{B}}_{\mathrm{y}}\right]}=\frac{\left(\mathrm{Cx\alpha }{)}^{\mathrm{x}}\right(\mathrm{Cy\alpha }{)}^{\mathrm{y}}}{\mathrm{C}-\mathrm{C}(\mathrm{x\alpha }-\mathrm{y\alpha })}={\mathrm{c}}^{\mathrm{x}+\mathrm{y}-1}{\mathrm{x}}^{\mathrm{x}}{\mathrm{y}}^{\mathrm{y}}{\mathrm{\alpha }}^{\mathrm{x}+\mathrm{y}}\\ =\frac{{\mathrm{C}}^{\left(\mathrm{x}+\mathrm{y}-1\right)}\left(\mathrm{x}{)}^{\mathrm{x}}\right(\mathrm{y}{{)}^{\mathrm{y}}\left(\mathrm{\alpha }\right)}^{\mathrm{x}+\mathrm{y}}}{1-\mathrm{\alpha }(\mathrm{x}+\mathrm{y})} \left(\mathrm{\alpha }<<1\right)\\ =\frac{{\mathrm{C}}^{\left(\mathrm{x}+\mathrm{y}-1\right)}\left(\mathrm{x}{)}^{\mathrm{x}}\right(\mathrm{y}{{)}^{\mathrm{y}}\left(\mathrm{\alpha }\right)}^{\mathrm{x}+\mathrm{y}}}{1}\\ \mathrm{\alpha }={\left[\frac{{\mathrm{K}}_{\mathrm{eq}}}{{\mathrm{C}}^{\left(\mathrm{x}+\mathrm{y}-1\right)}\left(\mathrm{x}{)}^{\mathrm{x}}\right(\mathrm{y}{)}^{\mathrm{y}}}\right]}^{\frac{1}{\mathrm{x}+\mathrm{y}}}\end{array}$