Introduction:
Copper sulphate is an inorganic compound that is commonly used in various industries such as agriculture, mining, and medicine. One of the interesting properties of copper sulphate is that its color changes when an iron nail is dipped into it. This phenomenon can be explained by a chemical reaction that occurs between copper sulphate and iron.

Chemical Reaction:
The chemical reaction that occurs when an iron nail is dipped into copper sulphate can be represented by the following equation:

Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)

The equation shows that iron reacts with copper sulphate to form iron(II) sulphate and copper. The iron from the nail displaces the copper from the copper sulphate solution, resulting in the formation of copper solid and iron(II) sulphate solution. The color change is due to the formation of copper solid, which has a reddish-brown color.

Explanation:
The color of copper sulphate solution is blue because of the presence of copper ions (Cu2+) in the solution. These ions absorb light in the red and orange regions of the visible spectrum and reflect light in the blue region. This is why copper sulphate solution appears blue to our eyes.

When an iron nail is dipped into the copper sulphate solution, the iron atoms displace the copper ions from the solution. As a result, the concentration of copper ions in the solution decreases, and the blue color fades away. At the same time, the displaced copper ions combine to form solid copper, which has a reddish-brown color. The formation of solid copper is a visible sign that the chemical reaction has occurred.

Conclusion:
The color change of copper sulphate solution when an iron nail is dipped into it can be explained by a chemical reaction that occurs between copper sulphate and iron. The reaction results in the displacement of copper ions from the solution, which causes the blue color to fade away. The displaced copper ions combine to form solid copper, which has a reddish-brown color.

Because iron is more reactive than copper. Therefore the colour of the copper sulphate solution changes.........:)