Question

$\text{5} \, \text{ml}$ of $As_{2}S_{3}$ is mixed with distilled water and $\text{0} \text{.01} \, \text{M}$ solution of an electrolyte $\text{AB}$ so that total volume is $\text{10} \, \text{ml}$ . It was found that all solution containing more than $\text{5} \, \text{ml}$ of $\text{AB}$ coagulate within $\text{5 min}$ . What is the Flocculation value of $\text{AB}$ for $As_{2}S_{3}$ sol?

Answer 1

A minimum of $\text{5} \, \text{ml}$ of $\text{AB}$ is required to coagulate the colloid,
The moles of $\text{AB}$ in colloid is $=\frac{5 \times 0.01}{10}=0.005 $ moles ,
This means that a minimum of $\text{0} \text{.005}$ moles or $0.005\times 1000$ millimoles
$=5$ milli moles are required for coagulation 1 litre of colloid.
So, Flocculation value of $\text{AB}$ for $As_{2}S_{3}$ colloid = $\text{5}$