How many coulombs are required to produce 29.9 g of aluminum metal from a sample of molten aluminum fluoride?

Answer 1

AlF₃ ==> Al³⁺ + 3F^-

Al³⁺ + 3e- ==> Al(s)

It requires 3 moles of electrons to plate 1 mole of Al(s).

29.9 g Al x 1 mol Al/26.98 g = 1.11 moles Al

1.11 mole Al x 3 moles electrons/mole Al = 3.33 moles of electrons

It takes 96,485 coulombs per mole of electrons

Coulombs required = 3.33 moles electrons x 96,485 C/mol e- = 321,295 C