9.9 Electrolytic Cell
An electrolytic cell is quite the opposite of a galvanic cell. I compare/contrast these cells below.
| Cell | Reaction | Electrical Energy | Anode | Cathode |
|---|---|---|---|---|
| Galvanic | spontaneous | produced | – | + |
| Electrolytic | nonspontaneous | consumed | + | - |
It is clear that an electrolytic cell consumes electrical energy to carry out a nonspontaneous reaction (called electrolysis).
Example
The following redox reaction is spontaneous
\[2\mathrm{H_2}(g) + \mathrm{O_2}(g) \longrightarrow \mathrm{2H_2O}(l)\]
whereas, the reverse reaction is not
\[2\mathrm{H_2O}(l) \longrightarrow \mathrm{2H_2}(g) + \mathrm{O_2}(g)\]
However, one can consume electrical energy to drive the splitting of water reaction. Today, many scientists are trying to harvest and apply solar power to split water into clean fuels (hydrogen and oxygen gas).