J.R. S. answered 01/04/21
Ph.D. University Professor with 10+ years Tutoring Experience
2 Al + 3F ==> 2AlF3 is not a balanced equation. You don't have the same number of atoms on each side. In addition, this reaction isn't feasible because F doesn't exist as such.
Perhaps, the reaction is supposed to be
2Al + 3F2 ==> 2AlF3
First, we must find the limiting reactant, if any.
moles Al present = 40 g Al x 1 mol Al / 27 g = 1.48 mol Al
moles F2 present = 57 g F2 x 1 mol F2 / 38 g = 1.50 mol F2
Since we need 3 mol F2 for every 2 mol Al, we don't have enough so F2 is limiting.
Amount AlF3 formed:
1.50 mol F2 x 2 mol AlF3 / 3 mol F2 x 84 g AlF3 / mol = 84 g AlF3 formed
Amount Al present after the reaction:
1.50 mol F2 x 2 mol Al / 3 mol F2 = 1 mol Al used up
1.48 mol Al - 1.0 = 0.48 mol Al left over
0.48 mol Al x 27 g/mol = 13 g Al left over after the reaction
No F2 left over after the reaction