For the coagulation of $50ml$ of ferric hydroxide sol. $10ml$ of $0.5MKCl$ is required. The coagulation value of $KCl$ is ____.

The coagulating value may be referred to as the number of millimoles of solute. The number of millimoles can be calculated as,

$\Rightarrow \frac{\text{ electrolyte required }}{\text{ Volume of colloidal solution(in litre) }}$

$\Rightarrow \frac{10\times 0.5}{50}\times 1000$

$\Rightarrow 100$

Hence the coagulation value is $100$.