Question

The coagulation of $200$ mL of a positive colloid took place when $0.73$ g $HCl$ was added to it without changing the volume much. The flocculation value of $HCl$ for the colloid is:

• A. $100$
• B. $36.5$
• C. $0.365$
• D. $150$

Answer 1

The correct option is A $100$

200 mL of the sol required = 0.73 g $HCl$.

The molecular weight of $HCl$ is $36.5$ g/mol.

$=\frac{0.73g}{36.5g/mol}=0.02mol=20mmol$

$\therefore$ 1000 mL (1 L ) of the sol will require

$=\frac{1000}{200}\times 20=100mmol$

Thus, the flocculation value of the $HCl$ for the colloid is $100$.