How many coulombs are required to produce 638 g of potassium
How many coulombs are required to produce 63.8 g of potassium metal from a sample of molten potassium chloride?
Solution
 each electron has 1.6x10^-19C charge
 
  atomic weight of K =39g/mol so63.8g = 63.8/39 = 1.635moles
 
  each mole has 6.022x10^23 atoms of K
 
  1.635 moles =9.85x10^23 atoms
 
  1 electrons off each atom, so  9.85x10^23  x 1 x 1.6x10^-19 =
 
  1.576 Million Coulombs, or 1.576 Megacoulombs

