A student places a zinc strip in a blue copper sulphate solution and claims that no chemical reaction has occurred. Which observation would prove the student's conclusion wrong?
Answer and explanation
Correct answer: The blue colour of the solution fades and a reddish-brown deposit of copper forms on the zinc strip
Zinc is more reactive than copper, so it displaces copper from copper sulphate solution: \(\mathrm{Zn + CuSO_4 \rightarrow ZnSO_4 + Cu}\). As blue \(\mathrm{Cu^{2+}}\) ions are removed, the solution fades and reddish-brown copper is deposited on the zinc strip. The hydrogen bubbles in option B are typically produced when a metal reacts with an acid, not with copper sulphate solution.
Frequently asked questions
What is the correct answer to this question?
The blue colour of the solution fades and a reddish-brown deposit of copper forms on the zinc strip
Why is this the correct answer?
Zinc is more reactive than copper, so it displaces copper from copper sulphate solution: \(\mathrm{Zn + CuSO_4 \rightarrow ZnSO_4 + Cu}\). As blue \(\mathrm{Cu^{2+}}\) ions are removed, the solution fades and reddish-brown copper is deposited on the zinc strip. The hydrogen bubbles in option B are typically produced when a metal reacts with an acid, not with copper sulphate solution.
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.
