COMEDK · Chemistry · 18. Electrochemistry
A dry cell consists of a moist paste of \(\mathrm{NH}_4 \mathrm{Cl}\) and \(\mathrm{ZnCl}_2\) contained in a \(\mathrm{Zn}\) casing which encloses a Carbon rod surrounded by black \(\mathrm{MnO}_2\) paste. What is the role of \(\mathrm{ZnCl}_2\) in it?
- A It acts as the anode while Carbon rod acts as the cathode.
- B It prevents pressure being developed in the cell due to \(\mathrm{NH}_3\) gas formation.
- C It serves as cathode thus permitting Carbon rod to act as anode.
- D It keeps the contents dry and prevents leakage of electrolyte.
Answer & Solution
Correct Answer
(B) It prevents pressure being developed in the cell due to \(\mathrm{NH}_3\) gas formation.
Step-by-step Solution
Detailed explanation
In a Leclanche dry cell, the zinc casing acts as the anode and the carbon rod acts as the cathode. The electrolyte is a moist paste of \(\mathrm{NH}_4\mathrm{Cl}\) and \(\mathrm{ZnCl}_2\). The chemical reaction at the cathode involves the reduction of \(\mathrm{MnO}_2\) and the…
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