Question

Why does the iron nail become brownish in colour and the blue colour of copper sulphate solution face?

Answer 1

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So when an iron nail is dipped in a solution of CuSO4, it displaces copper from the Solution, which gets deposited or precipitated as a red or red-brown residue. Also the blue colour of the solution gradually fades. Ultimately the solution becomes pale green in colour due to the formation of ferrous sulphate.

Answer 2

So when an iron nail is dipped in a solution of CuSO4, it displaces copper from the Solution, which gets deposited or precipitated as a red or red-brown residue. Also the blue colour of the solution gradually fades. Ultimately the solution becomes pale green in colour due to the formation of ferrous sulphate.