For redox reaction to proceed in a cell, the e.m.f must be

CONCEPT:

Electromotive Force (e.m.f) and Redox Reactions

• The electromotive force (e.m.f) of a cell is the measure of the energy per unit charge available from the redox reaction occurring in the cell.
• It is essentially the potential difference between the two electrodes of the cell when no current is flowing.
• The e.m.f of a cell is related to the spontaneity of the redox reaction taking place in the cell.

EXPLANATION:

• For a redox reaction to proceed spontaneously, the e.m.f of the cell must be positive.
• A positive e.m.f indicates that the cell reaction is spontaneous, meaning it can occur without any external energy input.
• Conversely, a negative e.m.f indicates a non-spontaneous reaction, which would require an external power source to proceed.
• If the e.m.f is zero, the cell is at equilibrium, and no net redox reaction will occur.

Therefore, for a redox reaction to proceed in a cell, the e.m.f must be positive.