Question

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Answer 1

The color of the copper sulfate changes from blue to green.

This happens as displacement reaction takes place.

Copper gets displaced from its sulfate solution by iron as iron is more reactive than copper. This forms Iron Sulfate.
The copper deposits on the nail forming a brown coating.

CuSO₄ + Fe ---> FeSO₄ + Cu

Refer the picture below!

Hope This Helps You!

Refer the reaction

Answer 2

REACTION -

Fe + CuSO4 ----->FeSO4 + Cu

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CHANGE-

the colour of the solution turns to light green from blue.

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REASON -

originaly the solution is blue in colour but the addition of Fe changes the colour of the solution to light green as Copper lies bellow iron in the activity series of metels . therefore it displaces Cu from CuSO4 solution . the new compound FeSO4 formed is light green in colour .