The degree of dissociation $(\alpha)$ of a weak electrolyte, $A_x B_y$ is related to van't Hoff factor (i)…

The degree of dissociation $(\alpha)$ of a weak electrolyte, $A_x B_y$ is related to van't Hoff factor (i) by the expression:
  1. $\alpha=\frac{i-1}{x+y+1}$
  2. $\alpha=\frac{x+y-1}{i-1}$
  3. $\alpha=\frac{x+y+1}{i-1}$
  4. $\alpha=\frac{i-1}{(x+y-1)}$

Solution

$ \begin{aligned} & i=1-\alpha+n \alpha=1+\alpha(n-1) \\ & \frac{i-1}{n-1}=\alpha \\ & A_x B_y \rightarrow x A^{+y}+y B^{-x} \\ & n=x+y \end{aligned} $ So $\alpha=\frac{i-1}{x+y-1}$

Asked in: JEE Main 2011

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