The Reddish Brown Coating Formed on the Nail in Copper Sulphate Solution

Introduction
When iron is placed in copper sulphate solution, a reddish-brown coating is formed on the nail. This process is known as displacement reaction. The coating that is formed on the nail is copper, which is a product of the reaction between iron and copper sulphate.

Displacement Reaction
Displacement reaction refers to a chemical reaction in which a more reactive element replaces a less reactive element in a compound. In the case of iron and copper sulphate, iron is more reactive than copper. Hence, when iron is placed in copper sulphate solution, iron displaces copper from its compound and forms a new compound with sulphate ions.

Formation of Copper
The reaction between iron and copper sulphate can be represented by the following equation:
Fe(s) + CuSO4(aq) -> FeSO4(aq) + Cu(s)
In this equation, Fe represents iron, CuSO4 represents copper sulphate, FeSO4 represents iron sulphate, and Cu represents copper. The reddish-brown coating that is formed on the nail is copper, which is produced as a result of this reaction.

Explanation
The reddish-brown coating that is formed on the nail is due to the deposition of copper on the surface of the iron nail. The copper ions in the solution are attracted to the iron nail and get deposited on it. The deposition of copper on the iron nail continues until all the copper ions in the solution are used up. The thickness of the coating depends on the concentration of the copper sulphate solution and the duration of the immersion of the iron nail in the solution.

Conclusion
In conclusion, when iron is placed in copper sulphate solution, a reddish-brown coating is formed on the nail due to the displacement reaction between iron and copper sulphate. The coating that is formed on the nail is copper, which is produced as a result of this reaction. The thickness of the coating depends on the concentration of the copper sulphate solution and the duration of the immersion of the iron nail in the solution.