Displacement Reaction: Iron Nail in Copper Sulphate Solution

A displacement reaction occurs when a more reactive element displaces a less reactive element from its compound.

Chemical Reactivity

Iron (Fe) is more reactive than Copper (Cu). Therefore, iron can displace copper from copper sulphate solution.

Reaction Details

The chemical reaction can be represented as:

Fe(s) + CuSO₄(aq) → FeSO₄(aq) + Cu(s)

Where:

• Fe is Iron
• CuSO₄ is Copper Sulphate (initially blue)
• FeSO₄ is Iron Sulphate (greenish solution)
• Cu is Copper (reddish-brown solid)

Observations Confirming Displacement

The reaction leads to specific observable changes:

• Colour Change: The characteristic blue colour of the copper sulphate solution fades because copper ions (Cu²⁺) are consumed. The solution may turn slightly greenish due to the formation of iron(II) sulphate (FeSO₄).
• Deposit Formation: A reddish-brown solid deposit forms on the iron nail. This deposit is copper metal (Cu), displaced from the solution.

Conclusion

These two key observations - the fading blue colour of the solution and the formation of a reddish-brown deposit on the iron nail - confirm that a displacement reaction has taken place.

Option B accurately describes these observations.