Question

If you had excess chlorine, how many moles of of aluminum chloride could be produced from 34.0 g of aluminum?

Answer 1

2Al + 3Cl2 → 2AlCl3

how many moles of Al in 34.0 g?
you will get that many moles of AlCl3
how many grams is that?

Answer 2

2Al + 3Cl2 --> 2AlCl3

mols Al = grams/atomic mass = 34.0/27 = 1.26
Convert to mols AlCl3 produced using the coefficients in the balanced equation this way: 1.26 mols Al x (2 mols AlCl3/2 moles Al) = 1.26 x 2/2 = 1.26.