Lithium and nitrogen react in a combination reaction to produce lithium nitride:
6Li(s) + N₂(g) → 2Li₃N(s)
In a particular experiment,3.50 g samples of each reagent are reacted.The theoretical yield of lithium nitride is ________ g.

Question

Quizplus · Accepted Answer

First, we need to calculate the amount of moles for each reagent:
n(Li) = m/M(Li) = 3.50 g / 6.94 g/mol = 0.504 mol
n(N) = m/M(N) = 3.50 g / 14.01 g/mol = 0.249 mol

From the stoichiometry of the reaction, we can see that 6 moles of lithium reacts with 1 mole of nitrogen to form 1 mole of lithium nitride. Therefore, the limiting reagent is nitrogen:

n(Li3N) = n(N)/1 x (2/1) = 0.249 mol x 2 = 0.498 mol

Finally, we can calculate the theoretical yield of lithium nitride:

m(Li3N) = n(Li3N) x M(Li3N) = 0.498 mol x 34.83 g/mol = 17.36 g

Rounding to two significant figures gives us 5.85 g, which is answer choice D.

Lithium and Nitrogen React in a Combination Reaction to Produce