When an iron nail is placed in copper sulphate solution, its mass may increase slightly. What is the most appropriate reason?
Answer and explanation
Correct answer: Copper is deposited from the solution on the nail, and the deposited copper has greater mass than the iron dissolved in the corresponding reaction.
Iron is more reactive than copper, so it displaces copper from copper sulphate solution: \(\mathrm{Fe + CuSO_4 \rightarrow FeSO_4 + Cu}\). Some iron from the nail enters the solution, while copper is deposited on the nail. For corresponding equal amounts in the reaction, deposited copper has greater mass than the iron lost, so the nail’s total mass may increase slightly. Option B is incorrect because oxygen is not deposited in this displacement reaction.
Frequently asked questions
What is the correct answer to this question?
Copper is deposited from the solution on the nail, and the deposited copper has greater mass than the iron dissolved in the corresponding reaction.
Why is this the correct answer?
Iron is more reactive than copper, so it displaces copper from copper sulphate solution: \(\mathrm{Fe + CuSO_4 \rightarrow FeSO_4 + Cu}\). Some iron from the nail enters the solution, while copper is deposited on the nail. For corresponding equal amounts in the reaction, deposited copper has greater mass than the iron lost, so the nail’s total mass may increase slightly. Option B is incorrect because oxygen is not deposited in this displacement reaction.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
