electrolytic cell

[determined daisy]

I found this line about electrolytic cell
The potential/voltage input + the cell potential must be > 0 for the reactions to occur.
What is potential/voltage input ,and the cell potential ?How these two differ?

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[EParker37]

I found this line about electrolytic cell
The potential/voltage input + the cell potential must be > 0 for the reactions to occur.
What is potential/voltage input ,and the cell potential ?How these two differ?

A lot of questions about electrochemical cells haha. Potential/voltage input is referring to a non-spontaneous cell that needs a current applied to work, and cell potential is the default potential of the cell based on the two electrodes. Anyway, what this is basically saying is that for any redox reaction to occur the cell potential or input voltage must have a voltage potential >0 for anything to happen. If I have two metals with a bridge and the cell potential is >0, then it is going to be spontaneous and will undergo a redox reaction between the anode(oxidized) and cathode(reduced), but if the cell potential is <0 then a current has to be applied to the circuit in order to overcome the fact that this reaction is non-spontaneous. To find the cell potential use the equation you had before, or the nernst equation.

 

[determined daisy]

The potential/voltage input + the cell potential must be > 0
So it means both of these potentials are present in electrolytic cell,right?
I know about voltage input but does electrolytic cell also have cell potential?

 

[EParker37]

The potential/voltage input + the cell potential must be > 0
So it means both of these potentials are present in electrolytic cell,right?
I know about voltage input but does electrolytic cell also have cell potential?

Voltage input is not present in the electrolytic cell's potential inherently. It would be coming from an external source. The cell potential is exactly what it sounds like, it is the cell's potential to do useful work. The reason it is saying both must equal greater than 0, is that if it didn't, nothing would happen. If I have a cell with a cell potential of -.74V and I apply a .5V external power source, my total electrolytic cell potential is now -.24V, which would still be non-spontaneous and nothing would happen. My external source must overcome the -.74V and then go above that for anything to happen. If however my cell potential is 1.1V (Which is the potential when you use zinc and copper if I'm not mistaken), then I don't need any voltage input, as I have overcome the >0 requirement from just the cell potential alone and the redox reaction will now happen. I would suggest doing some more reading about electrochemistry, and trying relate all these concepts with one another, and understand how gibbs free energy applies to this.

 

[determined daisy]

As per my knowledge Electrolytic cells have electrodes of same element,i.e cathode and anode both are made up of same element,then how can there be cell potential?

 

[EParker37]

Brain fart, but the principles are the same. You still have to overcome the negative or zero cell potential in order for the reaction to occur. If you use two electrodes of the same element, then the net cell potential is still a function of combining the potential of both electrodes for each half cell.