For the coagulation of 40ml of ferric hydroxide sol, 10ml of 0.4 M KCI is required. Then, coagulation value of KCI is

Options

A. 10
B. 50
C. 100
D. 40

Answer

To find the coagulation value of KCl for the coagulation of 40 ml of ferric hydroxide sol, we can follow these steps:

### Step 1: Identify the given data
- Volume of ferric hydroxide sol (V_colloid) = 40 ml
- Volume of KCl solution used (V_electrolyte) = 10 ml
- Molarity of KCl solution (C_electrolyte) = 0.4 M

### Step 2: Calculate the amount of KCl used
To find the amount of KCl used in moles, we can use the formula:
\[ \text{Moles of KCl} = \text{Volume (L)} \times \text{Molarity (mol/L)} \]
First, convert the volume of KCl from ml to liters:
\[ V_electrolyte = 10 \text{ ml} = \frac{10}{1000} \text{ L} = 0.01 \text{ L} \]
Now, calculate the moles of KCl:
\[ \text{Moles of KCl} = 0.01 \text{ L} \times 0.4 \text{ mol/L} = 0.004 \text{ moles} \]

### Step 3: Calculate the coagulation value
The coagulation value (C) is defined as the amount of electrolyte required to coagulate a unit volume of colloid. The formula for coagulation value is:
\[ C = \frac{\text{Electrolyte required (moles)}}{\text{Volume of colloids (L)}} \]
Substituting the values:
\[ C = \frac{0.004 \text{ moles}}{0.04 \text{ L}} = 0.1 \text{ mol/L} \]

### Step 4: Convert to appropriate units
Since coagulation value is typically expressed in terms of moles per liter, we can express this as:
\[ C = 0.1 \text{ mol/L} = 100 \text{ mM} \]

### Final Answer
Thus, the coagulation value of KCl is **100 mM**.

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