Aluminum oxide is formed by reaction of excess oxygen with aluminum.

Question

4 Al(s) + 3 O2(g) -> 2 Al2O3(s)

Calculate the mass of aluminum required to form 18.2 kg of aluminum oxide if the reaction has a percent yield of 83.4%.

Answer 1

4Al + 3O2 ==> 2Al2O3
kilomols Al2O3 = kg/molar mass = kmols needed at 100%. Call that ?
kmol needed at 89.4% = ?.0.894
Convert kmols Al2O3 to kmols Al using the coefficients in the balanced equation.
Now convert kmols to grams. kmols x atomic mass = kg Al.