## Tuesday, February 15, 2011

Michael Faraday, a pioneer in the properties of electric currents, formulated two basic laws of electrolysis:

FARADAY'S FIRST LAW may be stated as follows:

"The amount of any substance deposited, evolved, or dissolved at an electrode is directly proportional to the amount of electrical charge passing through the circuit."

The amount of electricity passing through the circuit in a given time is the number of moles of electrons passing through the circuit in that time, and the charge Q is related to the current I by The charge on the electron is 1.602 x 10-19 C, and Avogadro's number is 6.023 x 1023. It follows that one mole of electrons has a charge of 9.65 x 104 C. This quantity is known as the FARADAY or FARADAY'S CONSTANT (F). FARADAY'S SECOND LAW may be stated as follows:

 In the apparatus below, 1 Faraday will discharge 9 g Al (1/3 mole), 20 g Ca (1/2 mole) and 23 g Na (1 mole). The relevant half reactions are: Al3+ + 3e- Al Ca2+ +2e- Ca Na+ + e- Na 1. 