The mass of carbon anode consumed (giving only carbondioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is : (Atomic mass Al = 27)

In the Hall process for producing aluminum, the reaction at the cathode is Al3+ + 3e- → Al, and at the anode, the reaction is C + O2 → CO2. The mass of carbon consumed can be calculated based on the stoichiometry of the reaction and the mass of aluminum produced. For every 2Al produced, 3C are consumed (since 2Al3+ + 3C → 2Al + 3CO). Given that the atomic mass of Al is 27, the mass of 270 kg of Al corresponds to 270 / 27 = 10 moles of Al. Since 2 moles of Al require 3 moles of C, 10 moles of Al will require (3/2) 10 = 15 moles of C. The atomic mass of C is 12, so the mass of C consumed is 15 12 = 180 kg.