Question

Ionic strength of a solution made by mixing equal volumes of 0.01 M $NaCl$ and 0.02 M $AlC{l}_3$:

• A. $0.065$
• B. $0.13$
• C. $0.0325$
• D. $0.0216$

Answer 1

The correct option is A $0.065$

After mixing contration of [NaCl] =
$\frac{0.01}{2}=0.005$

After mixing concentration of $\left[AlC{l}_3\right]=\frac{0.02}{2}=0.0035$

$\Rightarrow \left[\begin{array}{ccccc}AlC{l}_3& \rightleftharpoons & A{l}^{\oplus }& +& 3C{l}^{\ominus }\\ 0.01& & 0& & 0\\ 0& & 0.01& & 3\times 0.01\\ TotalC{l}^{\ominus }& =& 0.05& +& 0.03\\ & & =& 0.035M& \end{array}\right]$

$\mu =\frac{1}{2}\left[0.005\right(1{)}^2+0.01(3{)}^2+0.35(1{)}^2]=0.065$