Question

How can an electrochemical cell be converted into an electrolytic cell ?

• A. Applying an external opposite potential greater than $E^\circ_{\text{cell}}$.
• B. Reversing the flow of ions in salt bridge.
• C. Applying an external opposite potential lower than $E^\circ_{\text{cell}}$.
• D. Exchanging the electrodes at anode and cathode.

Answer 1

The Correct Option is A

To understand how an electrochemical cell can be converted into an electrolytic cell, let's first review the basic operation of each type of cell:

• Electrochemical Cell (Galvanic Cell): This type of cell generates electrical energy from spontaneous chemical reactions. The potential difference between the electrodes drives the flow of electrons through an external circuit. The cell operates under a potential \(E^\circ_{\text{cell}}\) which is the standard cell potential.
• Electrolytic Cell: This type of cell uses external electrical energy to drive a non-spontaneous chemical reaction. In this configuration, an external voltage source is used to provide the energy necessary to force the reaction in the opposite direction.

To convert an electrochemical cell into an electrolytic cell, one needs to apply an external force that counteracts the natural direction of the reactions taking place in the electrochemical cell. This is done by:

1. Applying an External Opposite Potential: By applying an external potential that is greater than the standard cell potential \(E^\circ_{\text{cell}}\), the natural electron flow is reversed. The external voltage must overcome the natural potential of the cell and provide enough energy to drive the reaction in the reverse direction.

Therefore, the correct way to convert an electrochemical cell into an electrolytic cell is by applying an external opposite potential greater than \(E^\circ_{\text{cell}}\). This approach forces the redox reaction to proceed in the non-spontaneous direction, effectively using the cell as an electrolytic cell.

Let's evaluate the other options:

• Reversing the flow of ions in the salt bridge: This option is not feasible because the role of the salt bridge is to maintain charge balance by allowing ion flow, but it does not affect the spontaneity of the reaction itself.
• Applying an external opposite potential lower than \(E^\circ_{\text{cell}}\): This would not be sufficient to reverse the reaction. The applied potential must be greater than the cell's potential.
• Exchanging the electrodes at anode and cathode: This does not convert the cell from electrochemical to electrolytic; it merely changes the designation of the electrodes.

In conclusion, the correct answer is: Applying an external opposite potential greater than \(E^\circ_{\text{cell}}\).

Answer 2

To convert an electrochemical cell into an electrolytic cell, an external potential needs to be applied in the opposite direction. This applied potential should be greater than the standard cell potential \( E^\circ_{\text{cell}} \). When this condition is met, the cell reaction reverses, and the electrochemical cell functions as an electrolytic cell.