Question

If an opposing potential of $1.1V$ is applied to a galvanic cell of $1.1V$ electrical potential, what will happen to the cell reaction and current flowing through the cell?

• A. The cell reaction stops and no current flows through the cell.
• B. The cell reaction continuous but current flows in opposite direction.
• C. The concentration of reactants becomes unity and current flows from cathode to anode
• D. The cell does not function as a galvanic cell and zinc is deposited on zinc plate

Answer 1

The correct option is A The cell reaction stops and no current flows through the cell.

The electric potential of the given galvanic cell is $1.1V$.
The effect of opposing potential applied to galvanic cell as follows,

1. $E_{external}<1.1V$
If an external opposing potential is lower than electrical potential of the cell, the normal reactions of the cell will occur and the electrons will flow from anode to cathode. Hence, the current
flows from cathode to anode.

2. $E_{external}=1.1V$
When the external voltage is equal to the electrical potential of the cell, there will be no flow of electrons or current. Also, no chemical reaction.

3. $E_{external}>1.1V$
If an external opposing potential is higher than electrical potential of the cell, the reaction begins to take place in the opposite direction i.e., non-spontaneous process starts.
Electron will flow from cathode to anode. Thus, current flow from anode to cathode.
Here, anodic ions begins to deposit on anode and cathode metal begins to deteriorate.