Question

Q 24. What will be the colour of Iron filings and Copper Sulphate solution, when they
react with each other? (i) Before the experiment. (ii) After the experiment.
Give reason for the change in colour.​

Answer 1

Answer: Change in Colour of copper sulphate solution due to reaction with iron . When an iron nail immersed in the solution of copper sulphate than iron displaces copper from the solution of copper sulphate because iron is more reactive than copper. Therefore copper sulphate solution colour changes from blue to pale green.

Reaction

CuSO4 (aq) + Fe (s) → FeSO4 (aq) + Cu (s)

In this reaction following two processes take place:

Cu²⁺ + 2e = Cu⁰ (re­duc­tion process, Cu²⁺ is the ox­i­dizing agent)

Fe⁰ – 2e = Fe²⁺ (ox­i­da­tion process, Fe⁰ is the re­duc­ing agent)

The reaction can be double displacement reaction as well as redox reaction (oxidation and reduction both takes place simultaneously).

Explanation :

When an iron nail is dipped in copper sulphate solution, a brown coating of copper is formed in the surface of iron and the colour of copper sulphate solution changes from blue to pale green. The reaction shows that iron is more reactive than copper because it displaces copper from the copper sulphate solution. The iron passes into the solution as Fe (II) forming the ferrous sulphate solution.