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

Solution

Chemistry ma’am · 3 steps

Push back harder than the cell pushes: an opposing voltage above E⁰_(cell) reverses the reaction.

1. What each cell does. A galvanic (electrochemical) cell runs a spontaneous reaction and pushes electrons out with a voltage E_(cell). An electrolytic cell uses outside electrical energy to drive the non-spontaneous reverse reaction.

   External opposing voltage	Current	Cell behaves as
   Eₑₓₜ < E⁰_(cell)	flows from the cell, but smaller	galvanic cell
   Eₑₓₜ = E⁰_(cell)	zero, reaction stops	at balance
   Eₑₓₜ > E⁰_(cell)	reverses direction	electrolytic cell

2. Why it reverses. Once the outside source pushes harder than the cell, electrons are forced the other way. Oxidation and reduction swap places, and the cell now consumes electrical energy instead of producing it.
3. So. An external opposite potential greater than E⁰_(cell) converts the cell into an electrolytic cell, which is option (a).

The idea to keep. Think of it as a tug of war of voltages. The side that pushes harder decides the direction of the reaction. Only an opposing voltage larger than E⁰_(cell) reverses it.

Answer from the NTA final answer key. Solution by PrepWiser.