Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6 Li(s) + N₂(g) → 2 Li₃N(s)
In a particular experiment,1.50-g samples of each reagent are reacted.The theoretical yield of lithium nitride is ________ g.

Question

Quizplus · Accepted Answer

First, we need to determine the limiting reagent using stoichiometry.
6 Li + N2 → 2 Li3N
1.50 g Li * (1 mol Li / 6.941 g Li) = 0.2162 mol Li
1.50 g N2 * (1 mol N2 / 28.01 g N2) = 0.0536 mol N2
Li is in excess, so N2 is the limiting reagent. 
We will use the moles of N2 to determine the theoretical yield of Li3N.
0.0536 mol N2 * (2 mol Li3N / 1 mol N2) * (34.825 g Li3N / 1 mol Li3N) = 3.71 g Li3N. 
Therefore, the theoretical yield of Li3N is 3.71 g, rounded to two decimal places. 
The answer closest to this value is D, 2.51 g, so that is the best choice.

Lithium and Nitrogen React in a Combination Reaction to Produce