The number of moles of lead nitrate needed to coagulate 2 mole of colloidal `[AgI]I^(-)` is :

Options

A. 2
B. 1
C. `1//2`
D. `2//3`

Explanation

To solve the problem of how many moles of lead nitrate are needed to coagulate 2 moles of colloidal \( \text{AgI}^- \), we can follow these steps:

### Step 1: Understand the Coagulation Process
Coagulation involves the neutralization of the charge on the colloidal particles, leading to their aggregation and precipitation. In this case, we are dealing with colloidal \( \text{AgI}^- \) and lead nitrate, which provides \( \text{Pb}^{2+} \) ions.

### Step 2: Write the Reaction
When lead nitrate (\( \text{Pb(NO}_3\text{)}_2 \)) is added to the colloidal \( \text{AgI}^- \), the \( \text{Pb}^{2+} \) ions will react with the iodide ions to form lead iodide (\( \text{PbI}_2 \)) and silver iodide (\( \text{AgI} \)). The balanced chemical reaction can be represented as follows:

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