J.R. S. answered 11/04/19
Ph.D. University Professor with 10+ years Tutoring Experience
First, write a correctly balanced equation for the reaction taking place:
N2 + 3H2 ==> 2NH3
In order to find the percent yield, we must first find the theoretical yield, and to do that, we must first find the limiting reactant:
H2: 1.92 g H2 x 1 mol H2/2.0 g H2 = 0.96 mol H2 x 2 mol NH3/3 mol H2 = 0.64 moles NH3
N2: 9.73 g N2 x 1 mol N2/28.0 g N2 = 0.335 mol N2 x 2 mol NH3/1 mol N2 = 0.67 moles NH3
Thus, H2 is limiting.
Theoretical yield:
Using the limiting reactant, we see that only 0.64 moles of NH3 can be produced. Converting this to grams, ..
0.64 moles NH3 x 17.0 g/mol = 10.88 g NH3 = Theoretical yield
Percent yield:
Actual yield / theoretical yield (x100) = percent yield
2.04 g / 10.88 g (x100) = 18.8 percent