for the coagulation of 50 mL of ferric hydroxide sol 10 mL of 0.5 M KCl is required. What is the coagulation value of KCl ?

Options

A. 5
B. 10
C. 100
D. none of these

Answer

To find the coagulation value of KCl for the coagulation of ferric hydroxide sol, we can follow these steps:

### Step 1: Determine the number of millimoles of KCl used
We know that the volume of KCl solution used is 10 mL and its concentration is 0.5 M.

To calculate the number of millimoles of KCl:
\[ \text{Millimoles of KCl} = \text{Volume (mL)} \times \text{Concentration (M)} \]
\[ \text{Millimoles of KCl} = 10 \, \text{mL} \times 0.5 \, \text{M} = 5 \, \text{mmol} \]

### Step 2: Convert the volume of the colloidal solution to liters
The volume of the ferric hydroxide sol is given as 50 mL. To convert this to liters:
\[ \text{Volume (L)} = \frac{50 \, \text{mL}}{1000} = 0.050 \, \text{L} \]

### Step 3: Calculate the coagulation value
The coagulation value is defined as the number of millimoles of the electrolyte required per liter of the colloidal solution.

Using the formula:
\[ \text{Coagulation Value} = \frac{\text{Millimoles of KCl}}{\text{Volume of colloidal solution (L)}} \]
\[ \text{Coagulation Value} = \frac{5 \, \text{mmol}}{0.050 \, \text{L}} = 100 \, \text{mmol/L} \]

### Conclusion
The coagulation value of KCl is **100**.