Whys is the standard electrode potential (-) for electrolytic cells but positive for (+) galvanic cells.

  • If E°cell > 0, then the process is spontaneous (galvanic cell)
  • If E°cell < 0, then the process is non-spontaneous (electrolytic cell)

Thus in order to have a spontaneous reaction, E°cell must be positive, where:

E°cell = E°cathode − E°anode

^ above taken form wiki.

Also can someone please explain the follow:

In both cells is the electron flow from

anode -> cathode ??

For electrolytic cells isn't the electron flow from the battery (-) anode to cathode (-) of the cell.

Do we then show this by electron flow as cathode (-) ------> anode (+) [in the actual cell itself]??


1 Answer 1


Potential refers to the amount of energy produced or consumed by the reaction. If the sign for potential is (+) than the reaction is spontaneous (moves on its own). If the sign is (-) then the reaction requires energy to proceed.

In the case of electrolytic cells, the cell is used to decompose a compound. this can require energy depending on the reaction. Think of water and how much energy it takes to produce hydrogen gas and oxygen, that's an example of electrolytic cell doing work.

The definition of an anode is an electrode in which a positive charge flows into an electrical device, this is the direction of the electrons.

For both types of cells direction of electron flow would remain the same, but with electrolytic cells, there would be an additional object, the electrolyte, in the diagram.

Here is a decent picture i found that also does some explanation.

enter image description here

  • $\begingroup$ so basically for both galvanic/electrolytic cells anode -> cathode is the direction of e- flow $\endgroup$
    – confused
    Sep 24, 2014 at 1:34
  • 1
    $\begingroup$ Yes, anode gives off the electron and cathode receives. $\endgroup$
    – John Snow
    Sep 24, 2014 at 1:36

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