Cations present in slightly acidic solution are `Al^(3+),Zn^(3+) and Cu^(3+)`. The reagent which when added in excess to thiis solution would identity and separate `Cu^(2+)` in one step is:

Options

A. HCl acid
B. `NH_(3)` solution
C. NaOH solution
D. `Na_(2)CO_(3)` solution

Answer

To identify and separate Cu²⁺ ions from a solution containing Al³⁺, Zn²⁺, and Cu²⁺ in slightly acidic conditions, we can use sodium hydroxide (NaOH) as a reagent. Here’s a step-by-step solution:

### Step 1: Prepare the Solution
Start with the solution containing the cations: Al³⁺, Zn²⁺, and Cu²⁺. Ensure that the solution is slightly acidic, which can be achieved by adding a few drops of dilute hydrochloric acid (HCl) if necessary.

**Hint:** Ensure the solution is slightly acidic to keep the cations in solution.

### Step 2: Add Sodium Hydroxide (NaOH)
Add sodium hydroxide solution (NaOH) to the slightly acidic solution. It is important to add NaOH in excess to ensure complete precipitation of the copper ions.

**Hint:** Add NaOH slowly and observe the changes in the solution.

### Step 3: Observe the Precipitation
As NaOH is added, Cu²⁺ ions will react with the hydroxide ions (OH⁻) from NaOH to form copper(II) hydroxide, Cu(OH)₂, which is a blue precipitate.

The reaction can be represented as:
\[ \text{Cu}^{2+} + 2 \text{OH}^- \rightarrow \text{Cu(OH)}_2 \downarrow \]

**Hint:** Look for a color change indicating the formation of a blue precipitate.

### Step 4: Filter the Precipitate
After the formation of the blue precipitate (Cu(OH)₂), filter the mixture to separate the solid precipitate from the remaining solution. The precipitate contains the Cu(OH)₂, while the remaining solution contains Al³⁺ and Zn²⁺ ions.

**Hint:** Use filter paper and a funnel to effectively separate the precipitate.

### Step 5: Confirm the Presence of Cu²⁺
To confirm the presence of Cu²⁺, you can dissolve the precipitate in a small amount of dilute hydrochloric acid (HCl) to form a clear solution again. This confirms that Cu²⁺ was successfully separated.

**Hint:** The re-dissolution of the blue precipitate in acid indicates the presence of copper ions.

### Conclusion
By following these steps, you can effectively identify and separate Cu²⁺ ions from a mixture of cations in a slightly acidic solution using sodium hydroxide.

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