The overall reaction for the electrolysis of molten sodium chloride,

2 NaCl(l) −→−−−−−−electric current 2 Na(l)+Cl2(g)
can be expressed as two separate, simultaneous redox processes (Reactions 1 and 2):

2 Cl−→ Cl2(g)+2 e−
Reaction 1

2 Na++2 e−→2 Na(l)
Reaction 2

What is the amount of electric charge required to produce 0.80 mol of Na(l) during the electrolysis?

0.80 mol Na(l)×2 mol NaCl(l)2 mol Na(l)=0.80 mol NaCl(l)
Reactions 1 and 2 show that 2 moles of electrons are required for every 2 moles of NaCl(l) that undergo electrolysis. Consequently, the electrolysis of 0.80 mol NaCl(l) requires:

0.80 mol NaCl(l)×2 mol e−2 mol NaCl(l)=0.80 mol e−
The charge used during electrolysis can be measured in a unit called the faraday, where 1 faraday equals the electric charge present in 1 mole of electrons. Accordingly, the number of faradays present in 0.80 mol e− is:

0.80 mol e−×1 faraday1 mol e−=0.80 faradays