Question

If $M_{normal}$ is the normal molecular mass and $\alpha$ is the degree of ionization of $K_3\left[Fe\right(CN{)}_6]$, then the abnormal molecular mass of the complex in the solution will be:

• A. $M_{normal}(1+2\alpha {)}^{-1}$
• B. $M_{normal}(1+3\alpha {)}^{-1}$
• C. $M_{normal}(1+\alpha {)}^{-1}$
• D. equal to $M_{normal}$

Answer 1

The correct option is B

$M_{normal}(1+3\alpha {)}^{-1}$

$\begin{array}{ccc}{K}_3\left[Fe\right(C{N}_6\left)\right]\to & 3K^{+}& +\left[Fe\right(CN{)}_6{]}^{3-}\\ & & \\ 1& -& -\\ 1-\alpha & 3\alpha & \alpha \end{array}$

$i=1-\alpha +3\alpha +\alpha =(1+3\alpha )$

$i=\frac{M_{normal}}{M_{abnormal}}$

$M_{abnormal}=M_{normal}(1+3\alpha {)}^{-1}$