Question

The cell reaction $Cu+2Ag^{+}\rightarrow Cu^{2+}+2Ag$ is best represented by
A. $Cu_{(s)}|Cu^{2+}_{(aq)}||2Ag^{+}_{(aq)}|2Ag_{(s)}$
​B. $Pt|Cu^{2+}||Ag^{+}_{(aq)}|Ag_{(s)}$
​C. $Cu^{2+}|Cu||Pt|2Ag$
D. None of the above representations

Answer 1

Hint: A cell is a device that is used to convert chemical energy produced from a redox reaction into electrical energy. Redox reaction implies reduction and oxidation reactions.

Complete Step by Step Solution:
A cell consists of a glass vessel that has an electrolyte in its aqueous or molten state.
Two metal rods dipped into it are attached with a battery and are called electrodes.
The electrodes attached to the positive and negative terminal of the battery are called anode and cathode.

We know that oxidation is the process by which the loss of electrons happens.
Oxidation happens at the anode.
Reduction is the process by which the gain of electrons happens.
Reduction happens at the cathode.

In the given reaction, copper undergoes oxidation i.e., loses electrons to form copper(II) cation.
It changes from 0 to +2 oxidation state.

The oxidation half-reaction is as follows:
$Cu_{(s)}\rightarrow Cu^{2+}_{(aq))}+2e^{-}$
The silver undergoes reduction i.e., gains an electron.
It changes from +1 to 0 oxidation state.

The reduction half-reaction is as follows:
$2Ag^{+}_{(s)}+2e^{-}\rightarrow2Ag_{(aq)}$
These two solutions are connected by a salt bridge. It is a U-shaped tube possessing a concentrated solution of an inert electrolyte like KCl.
It helps in maintaining electrical neutrality.

The cell reaction is best represented by:
$Cu_{(s)}|Cu^{2+}_{(aq)}||2Ag^{+}_{(aq)}|2Ag_{(s)}$
where double lines in between the solution represent the salt bridge.
So, option A is correct.

Note: Oxidation is the loss of electrons. Reduction is the gain of electrons. While representing a cell reaction, the metal gets oxidised and the ion formed by it is represented first followed by an indication of the salt bridge. At last, the ion which gets reduced and the metal formed by it is depicted.