Question

The ionic strength of solution containing $0.3$ N ${Al}_2{\left(S{O}_4\right)}_3$ is

• A. 0.75
• B. 1.85
• C. 3.9
• D. 1.5

Answer 1

The correct option is A 0.75

$0.3$N ${Al}_2{\left(S{O}_4\right)}_3=\frac{0.3}{6}M{Al}_2{\left(S{O}_4\right)}_3=0.05M$
$\left[A{l}^{3+}\right]=2\times 0.05M$

$\left[S{O}_4^{2-}\right]=3\times 0.05M$

Ionic strength of solution $=\frac{1}{2}[0.05\times 2\times 3^2+0.05\times 3\times 2^2]$
$=\frac{1.5}{2}=0.75$