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When excess of NH(3) (aq) is added to a ...

When excess of `NH_(3)` (aq) is added to a blue solution containing `Cu_((aq))^(2+)` ions

A

Solution turns red due to formation of `Cu^(+)` ions

B

Solution becomes red due to formation of `[Cu (NH_(3))_(4)]_(aq)^(2+)`

C

Solution become deep blue due to formation of `[Cu(NH_(3))_(4)]_(aq)^(2+)`

D

Solution becomes colourless due to excess colourless `NH_(3)`

Text Solution

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The correct Answer is:
### Step-by-Step Solution: 1. **Identify the Initial Solution**: We start with a blue solution containing copper ions, specifically \( Cu^{2+} \) ions. This blue color is typically due to the presence of copper sulfate (\( CuSO_4 \)) in the solution. 2. **Add Excess Ammonia**: When excess ammonia (\( NH_3 \)) is added to the solution, it interacts with the copper ions. Ammonia acts as a ligand and coordinates to the copper ions. 3. **Formation of the Complex**: The reaction between \( Cu^{2+} \) ions and ammonia leads to the formation of a complex ion. The complex formed is \( [Cu(NH_3)_4]^{2+} \). This complex ion consists of one copper ion surrounded by four ammonia molecules. 4. **Color Change**: The addition of ammonia changes the color of the solution. The original blue color of the \( Cu^{2+} \) ions intensifies to a deeper blue due to the formation of the tetraamminecopper(II) complex, \( [Cu(NH_3)_4]^{2+} \). 5. **Final Products**: The final products of this reaction are the tetraamminecopper(II) complex and the sulfate ions (\( SO_4^{2-} \)) that remain in solution. The overall reaction can be summarized as: \[ Cu^{2+} + 4 NH_3 \rightarrow [Cu(NH_3)_4]^{2+} \]
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