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  • The use of electric current to stimulate a non-spontaneous reaction. Electrolysis can be used to separate a substance into its original components/elements and it was through this process that a number of elements have been discovered and are still produced in today's industry. In Electrolysis, an electric current it sent through an electrolyte and into solution in order to stimulate the flow of ions necessary to run an otherwise non-spontaneous reaction. Processes involving electrolysis include: electro-refining, electro-synthesis, and the chloro-alkali process.

    Electrolytic Cell vs Voltaic Cell

    Example: When we electrolyze water by passing an electric current through it, we can separate it into hydrogen and oxygen.

    \[ 2 H_2O(l) \rightarrow 2H_2(g) + O_2(g) \]

    More information : The Electrolysis of Water

    An electrolytic cell is essentially the non-spontaneous reaction's voltaic cell, (in fact if we reversed the flow of electricity within a voltaic cell by exceeding a required voltage, we would create an electrolytic cell). Electrolytic cells consist of two electrodes (one that acts as a cathode and one that acts as an anode), and an electrolyte. Unlike a voltaic cell, reactions using electrolytic cells must be electrically induced and it's anode and cathode are reversed (anode on the left, cathode one the right).

    Voltaic Electrolytic
    Oxidation: X → X+ + e- (Negative Anode) Y → Y+ + e- (Positive Anode)
    Reduction: Y+ + e- → Y (Positive Cathode) X+ + e- → X (Negative Cathode)
    Overall: X + Y+→ X+ + Y (G<0) X+ + Y → X + Y+ (G>0)
    This reaction is spontaneous and will release energy This reaction is non-spontaneous and will absorb energy


    Contributors and Attributions

    • Kimberly Song (UC Davis)