Electrolytic Cells

The Setup

The entire reaction system, including the electrodes and solution/molten ionic compound, are located inside a chamber. The wires attached to the electrodes are connected to an external power source. 

The Reduction-Oxidation Mechanism

The external power source provides the electrical current (flow of electrons) needed to drive the reaction. The current induces an electrical potential difference (voltage) to drive the reaction by pulling the electrons toward the cathode, making the anode positively-charged (to attract electrons) and the cathode negatively-charged (to donate electrons). 

Different electrolytic reactions require varying levels of electric potential. 

Cathode: The electrode that hosts the reduction half-reaction. 

Anode: The electrode that hosts the oxidation half-reaction. 

Anions of the solution/liquid are attracted to the anode. After coming in contact with the anode, the anion will donate its electrons to the anode and become a neutral atom. 

Xⁿ⁻ (aq) → X (s) + ne⁻ 

Cations of the solution/liquid are attracted to the cathode. Electrons that originated from the anode will flow to the cathode and into the cations, reducing their charges to neutral. 

Yⁿ⁺ (aq) + ne⁻ → Y (not aq) 

Overall reaction equation: 

Xⁿ⁻ (aq) + Yⁿ⁺ (aq) → X (not aq) + Y (not aq) (ΔG > 0)