How many coulombs of charge are necessary to produce 395 g of Al from Al³⁺(aq)? (F = 96,500 C/mol)

Answer 1

To go from Al³⁺(aq) to Al (s) will require 3 moles of electrons per mol of Al.

Al³⁺(aq) + 3e ==> Al(s)

How many moles of Al is 395 g?

395 g Al x 1 mol Al / 26.98 g = 14.64 mols Al

Calculate moles of electrons:

14.64 mols Al x 3 mols e- / mol Al = 43.92 mols e-

Finally, calculate coulombs (C) needed:

43.92 mols e- x 96,500 C / mol e- = 4,238,280 C = 4.24x10⁶ C (3 sig.figs.)