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Question: Answered & Verified by Expert
In the Daniell cell, \(\mathrm{Zn}\left|\mathrm{Zn}^{2+} \| \mathrm{Cu}^{2+}\right| \mathrm{Cu}\), when an external voltage is applied such that \(E_{\text {external }}>E_{\text {cell }}\), current flows from.........
ChemistryElectrochemistryAP EAMCETAP EAMCET 2020 (21 Sep Shift 1)
Options:
  • A \(\mathrm{Zn}\) to \(\mathrm{Cu}\)
  • B Cu to \(\mathrm{Zn}\)
  • C no current flows
  • D data insufficient
Solution:
1899 Upvotes Verified Answer
The correct answer is: \(\mathrm{Zn}\) to \(\mathrm{Cu}\)
On applying an external voltage greater than \(1.1 \mathrm{~V}\) in a Daniell cell, the current flows in the reverse direction i.e., from \(\mathrm{Zn}\) to \(\mathrm{Cu}\) (cathode to anode) and electrons flow from \(\mathrm{Cu}\) to \(\mathrm{Zn}\).
\(\mathrm{Zn}\) is deposited at \(\mathrm{Zn}\) electrode and \(\mathrm{Cu}\) dissolves at \(\mathrm{Cu}\) electrode. The reaction is
\(\mathrm{Zn}^{2+}+\mathrm{Cu} \longrightarrow \mathrm{Zn}+\mathrm{Cu}^{2+}\)

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