the colour of the solution observed after 30 minutes of placing zinc metal to copper sulphate solution is
When zinc metal is placed in a copper sulfate solution, a redox reaction occurs. This reaction leads to the deposition of copper metal on the surface of the zinc and the formation of zinc sulfate in solution.
Initial Observation
The initial color of copper sulfate (\text{CuSO}_4 ) solution is typically blue due to the presence of \text{Cu}^{2+} ions. This is because these ions are responsible for the blue color as they absorb certain wavelengths of light.
Change Over Time
- After 30 minutes, as the zinc reacts with the copper sulfate, copper metal starts to precipitate out of the solution. The copper ions accept electrons from the zinc, reducing themselves to solid copper, which has a reddish-brown color.
- Concurrently, the formation of zinc sulfate in the solution causes the blue color to fade. Since zinc sulfate is colorless, the solution will lose its blue hue over time.
Final Color Change
- Solution Color Change: The blue color will gradually change to a colorless solution as \text{Cu}^{2+} ions are replaced by \text{Zn}^{2+} ions.
- Deposit Appearance: The reddish-brown copper will begin to deposit on the zinc surface.
Chemical Reaction
The chemical equation representing this redox reaction is:
\text{Zn(s) + CuSO}_4(\text{aq}) \rightarrow \text{ZnSO}_4(\text{aq}) + \text{Cu(s)}
Explanation
In this reaction:
- Zinc (Zn) acts as a reducing agent, losing two electrons and oxidizing to form \text{Zn}^{2+} ions.
- Copper ions (( \text{Cu}^{2+} )) are the oxidizing agent, gaining the electrons lost by zinc and reducing to form copper metal.
Hence, the overall observation 30 minutes after introducing zinc to a copper sulfate solution would likely show a colorless solution due to the absence of \text{Cu}^{2+} ions, and reddish-brown copper metal precipitated on the zinc.
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