Example. When 96,487 coulombs of electricity are passed through an electrolysis cell containing molten NaCl, how many moles, and how many grams, of Na and Cl₂ are produced?

Example. Exactly 200,000 coulombs of electricity are passed through an electrolysis cell containing a copper sulfate solution that is designed to purify copper electrolytically. How much copper will plate on the cathode?

Solution

In acid-base neutralizations , the amount of substance that would release or take up one mole of protons was referred to as one equivalent of acid or base. Hence one equivalent of acid-base neutralizing ability is supplied by one mole of HCl or NaOH, one half mole of H₂SO₄, or one third mole of H₃PO₄. In a similar manner, we can define one redox equiualent of a substance being reduced or oxidized as that amount of substance that takes up or releases one mole of electrons, or one faraday.

Hence in the first example of this section, one mole of sodium metal and one half mole of Cl₂ gas each represent one redox equivalent. In the second example, one mole of copper represents two redox equivalents in the reduction of Cu²⁺ to Cu, since two moles of electrons, or faradays, of electricity are needed