`AgI darr+2Na_(2)S_(2)O_(3) to Na_(3)[Ag(S_(2)O_(3))_(2)]+NaI`

Options

A. For precipitate formation reaction
B. For precipitate dissolution reaction
C. For precipitate exchange reaction
D. For no reaction

Answer

To analyze the reaction \( \text{AgI} + 2\text{Na}_2\text{S}_2\text{O}_3 \rightarrow \text{Na}_3[\text{Ag}(\text{S}_2\text{O}_3)_2] + \text{NaI} \), we will determine what type of reaction it represents. Here are the steps to arrive at the conclusion:

### Step 1: Identify the Reactants and Products
- **Reactants**: Silver iodide (\( \text{AgI} \)) and sodium thiosulfate (\( \text{Na}_2\text{S}_2\text{O}_3 \)).
- **Products**: Sodium thiosulfate complex with silver (\( \text{Na}_3[\text{Ag}(\text{S}_2\text{O}_3)_2] \)) and sodium iodide (\( \text{NaI} \)).

### Step 2: Analyze the State of Reactants and Products
- **Reactant Side**: \( \text{AgI} \) is a precipitate (solid).
- **Product Side**: The complex \( \text{Na}_3[\text{Ag}(\text{S}_2\text{O}_3)_2] \) is soluble in water, and \( \text{NaI} \) is also soluble.

### Step 3: Determine the Type of Reaction
- Since \( \text{AgI} \) (a precipitate) is present on the reactant side and is no longer visible on the product side, it indicates that it has been dissolved in the reaction.
- The formation of soluble products from an insoluble reactant suggests that this is a **precipitate dissolution reaction**.

### Conclusion
Based on the analysis, the reaction \( \text{AgI} + 2\text{Na}_2\text{S}_2\text{O}_3 \rightarrow \text{Na}_3[\text{Ag}(\text{S}_2\text{O}_3)_2] + \text{NaI} \) is classified as a **precipitate dissolution reaction**.

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