When a small quantity of aqueous solution of Kl is added to a very dilute aqueous solutins of silver nitrate,the colloidal particles of silver iodide which are associated with Helmholtz double layer

Options

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Explanation

To solve the question regarding the addition of a small quantity of aqueous solution of KI to a very dilute aqueous solution of silver nitrate (AgNO3) and its effect on colloidal particles of silver iodide (AgI) associated with the Helmholtz double layer, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Reaction**:
When KI is added to AgNO3, a precipitation reaction occurs. The iodide ions (I⁻) from KI react with silver ions (Ag⁺) from AgNO3 to form silver iodide (AgI), which is a colloidal substance.

**Reaction**:
\[ \text{Ag}^+ (aq) + \text{I}^- (aq) \rightarrow \text{AgI} (s) \]

2. **Formation of Colloidal Silver Iodide**:
The AgI formed is in a colloidal state, meaning it exists as small particles suspended in the solution. These particles can be stabilized by electrical charges.

3. **Helmholtz Double Layer**:
The colloidal particles of AgI are associated with a Helmholtz double layer, which consists of a layer of charged particles (in this case, Ag⁺ ions) adsorbed on the surface of the AgI particles. This layer helps stabilize the colloid by preventing the particles from aggregating.

4. **Effect of Adding KI**:
When KI is added, the iodide ions (I⁻) will interact with the Ag⁺ ions already present in the solution. As more AgI is formed, the positively charged Ag⁺ ions will be attracted to the surface of the AgI particles, enhancing the positive charge of the colloidal particles.

5. **Resulting Charge on Colloidal Particles**:
The increase in Ag⁺ ions adsorbed on the AgI particles will lead to the formation of a positively charged colloidal solution. This positive charge is crucial for the stability of the colloid, as it helps to maintain the separation between the particles.

6. **Conclusion**:
The addition of KI to the dilute AgNO3 solution results in the formation of positively charged colloidal silver iodide particles due to the adsorption of Ag⁺ ions on the surface of the AgI particles.

### Summary of the Solution:
- KI reacts with AgNO3 to form AgI.
- AgI exists as colloidal particles stabilized by a Helmholtz double layer.
- Adding KI increases the concentration of Ag⁺ ions, enhancing the positive charge on AgI particles.