For the complete precipitation of of an colloidal sol, exactly of a electrolyte solution is experime — Surface Chemistry Chemistry Question

💡 Solution & Explanation

Flocculation (coagulation) value is defined strictly as the minimum millimoles of electrolyte required to coagulate one litre ($1\text{ L}$) of the colloidal sol. Moles of $BaCl_2$ added $= 10\text{ mL} \times 1\text{ M} = 10\text{ millimoles}$. The total volume of the sol coagulated is $200\text{ mL} = 0.2\text{ L}$. Flocculation value $= \frac{10\text{ mmol}}{0.2\text{ L}} = 50\text{ mmol L}^{-1}$.