To solve the problem, we need to determine the flocculation value of the electrolyte AB for the As₂S₃ sol. The flocculation value is defined as the minimum concentration of the electrolyte in millimoles that must be added to 1 liter of sol to bring about complete coagulation.
### Step-by-Step Solution:
1. **Understanding the Given Information:**
- We have 5 ml of As₂S₃ mixed with distilled water and a 0.01 M solution of electrolyte AB, resulting in a total volume of 10 ml.
- It is stated that solutions containing more than 5 ml of AB coagulate within 5 minutes.
2. **Calculate the Moles of AB in the Solution:**
- The molarity (M) of the AB solution is given as 0.01 M.
- The total volume of the solution is 10 ml, which is equivalent to 0.01 L.
- The number of moles of AB can be calculated using the formula:
\[
\text{Moles of AB} = \text{Molarity} \times \text{Volume in Liters}
\]
\[
\text{Moles of AB} = 0.01 \, \text{mol/L} \times 0.01 \, \text{L} = 0.0001 \, \text{mol} = 0.1 \, \text{mmol}
\]
3. **Determine the Minimum Amount of AB Required for Coagulation:**
- It is found that solutions with more than 5 ml of AB coagulate. Therefore, we can assume that 5 ml of AB is the minimum required for coagulation.
- Since we have 0.1 mmol of AB in 10 ml, we can find out how much is needed for 5 ml:
\[
\text{Amount of AB in 5 ml} = \frac{0.1 \, \text{mmol}}{10 \, \text{ml}} \times 5 \, \text{ml} = 0.05 \, \text{mmol}
\]
4. **Calculate the Flocculation Value:**
- The flocculation value is the amount of AB required to coagulate 1 liter of As₂S₃ sol. Since we found that 0.05 mmol is required for 5 ml, we can scale this up to 1 liter (1000 ml):
\[
\text{Flocculation Value} = 0.05 \, \text{mmol} \times \frac{1000 \, \text{ml}}{5 \, \text{ml}} = 10 \, \text{mmol}
\]
5. **Final Calculation:**
- Since the flocculation value is defined as the amount in millimoles per liter, we can conclude that:
\[
\text{Flocculation Value} = 10 \, \text{mmol/L}
\]
### Conclusion:
The flocculation value of AB for As₂S₃ sol is **10 millimoles per liter**.
