Question

Which type of reaction takes place when an iron is dipped in a solution of copper sulphate?

• A. Combination
• B. Displacement
• C. Decomposition
• D. None of these

Answer 1

Answer:

B. Displacement

When an iron nail is dipped in a solution of copper sulphate, a single displacement reaction (or simply a displacement reaction) takes place.

What Happens During the Reaction?

Iron is more reactive than copper on the chemical reactivity series. Because of this, the iron displaces (pushes out) the copper from its salt solution.

• The Chemical Equation:
  $\text{Fe (s)} + \text{CuSO}_4 \text{ (aq)} \rightarrow \text{FeSO}_4 \text{ (aq)} + \text{Cu (s)}$
  $\text{[Iron]} + \text{[Copper Sulphate]} \rightarrow \text{[Iron Sulphate]} + \text{[Copper]}$

Visible Changes to Look For:

• Color change of the solution: The initial deep blue color of the copper sulphate solution gradually fades and turns into a light green color due to the formation of iron sulphate ($\text{FeSO}_4$).

• Change on the iron nail: A reddish-brown coating of solid copper metal deposits on the surface of the iron nail.