Question

To coagulate $100ml$ of a colloid, $1litre$ of $0.03NMgC{l}_2$ is required. Then, the flocculation value of $MgC{l}_2$ is

Answer 1

Answer: 150

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 $MgC{l}_2=$ Normality $\times$ volume$=0.03\times 1=0.03$
Normality= molarity $\times n.$ factor molarity $=\frac{\text{Normality}}{n.\text{factor}}=\frac{0.03}{2}=0.015$
$100mL$ of colloid requires $15$ millimoles then one litre $\left(1000ml\right)$ requires
$\frac{15\times 1000}{100}=150$ millimoles.
So, flocculation value $=150$ .