CAS CH 110 Lecture Notes - Lecture 26: Galvanization, Calcium Chloride, Electrolytic Cell

• School: Boston University
• Department: Chemistry
• Course: CAS CH 110
• Professor: Pinghua Liu

Document Summary

A nonspontaneous reaction, driven by an external power supply. Anode: 2cl- (melt) cl2(g) + 2 e- Cathode: mg2+ (melt) + 2 e- mg(l) Electrons are forced into the cathode and are drawn toward a higher potential anode. Overpotential, having to apply a higher voltage than the potential sited in a table. In practice, the applied potential must be substantially greater than the cell emf. The additional potential is called the overpotential; this is common for many reactions. 2 h2(g) + o2(g) 2 h2o(l) e = +1. 23 v at ph = 7. For platinum electrodes, the overpotential for the production of water from hydrogen and oxygen is 0. 6 v more or about 1. 8v (0. 6 + 1. 23)v. Pure water of course can not conduct electricity. Pure water will not conduct but add solute and it will; O2(g) + 4 h+ + 4 e- 2 h2o(l) e = +0. 82v, typically sea-water. To oxidize sea-water we would apply the opposite voltage,