Question

To coagulate $100\,ml$ of a colloid, $1litre$ of $0.03\,N\,MgCl_{2}$ is required. Then, the flocculation value of $MgCl_{2}$ is

Answer 1

Flocculation value is defined as the minimum concentration (in millimoles per litre) of an electrolyte required to cause the coagulation of a sol.
The coagulating power of an electrolyte is usually expressed in terms of its flocculation value.
Gram equivalents of $MgCl_{2}=$ Normality $\times$ volume$ =0.03\times 1=0.03$
Normality= molarity $ \times n.$ factor molarity $=\frac{\text{Normality}}{n . \text{factor}}=\frac{0 . 03}{2}=0.015$
$100\,mL$ of colloid requires $15$ millimoles then one litre $\left(1000 ml \right)$ requires
$\frac{15 \times 1000}{100}=150$ millimoles.
So, flocculation value $=150$ .