Question

Identify the true statement regarding Daniel cell:
A) Zinc ions flow across salt bridge
B) $\mathrm{K}^{+}$ ions move from salt bridge to $\mathrm{Cu} / \mathrm{Cu}^{2+}$ half cell
C) Oxidation takes place at copper electrode
D) Flow of current takes place from copper electrode to zinc electrode

Answer 1

Hint: Daniell cell is a type of cell that is electrochemical in nature. It consists of a copper pot filled with copper(II) sulphate solution, sulphuric acid and zinc electrode.

Complete step by step answer:
In the wet-cell during discharge, nitrate anions in the salt bridge move into the zinc half-cell in order to balance the increase in $\mathrm{Zn}^{2+}$ ions. At the same time, potassium ions from the salt bridge move into the copper half-cell in order to replace the $\mathrm{Cu}^{2+}$ ions being precipitated onto the copper electrode.

At anode:
$\mathrm{Zn}_{(\mathrm{s})} \rightarrow \mathrm{Zn}_{(\mathrm{aq})}^{2+}+2 \mathrm{e}^{-}$
At cathode:
$\mathrm{Cu}_{(\mathrm{aq})}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Cu}_{(\mathrm{s})}$
The total reaction is:
$\mathrm{Zn}(\mathrm{s})+\mathrm{Cu}^{2+}(\mathrm{aq}) \rightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s})$

The Daniell cell performs the spontaneous redox reaction between zinc and cupric ions to
produce an electric current. It consists of two half-cells. The left half cell contains a zinc metal
electrode ZnSO dipped in solution.The half right half cell consists of copper metal electrode in
a solution $\mathrm{CuSO}_{4}$ solution.The half-cells are joined by a salt bridge that prevents the mixing of the solution.
In Daniel cell flow of current takes place from copper electrode to zinc electrode.
So, the correct answer is “Option D”.

Note: Daniell cell is an electrochemical cell. Do not confuse this with electrolytic cells. Electrolytic cell is a different cell, in which the electrical energy is converted into chemical energy.