Lithium and nitrogen react in a combination reaction to produce lithium nitride: 6Li (s) + N₂(g) → 2Li₃N (s)
In a particular experiment,2.50-g samples of each reagent are reacted.The theoretical yield of lithium nitride is ________ g.

Question

Quizplus · Accepted Answer

To find the theoretical yield of lithium nitride, we need to first determine the limiting reagent. 
The balanced chemical equation shows that for every 6 moles of lithium (Li) used, we need 1 mole of nitrogen (N2). 
Converting the mass of each reagent to moles: 
2.50g Li x (1 mole Li/ 6.941 g Li) = 0.360 moles Li 
2.50g N2 x (1 mole N2/ 28.0134 g N2) = 0.0894 moles N2 
Since the ratio of Li:N2 in the reaction is 6:1, we can see that N2 is the limiting reagent because we don't have enough N2 to react with all the Li. 
Using the mole ratio from the balanced equation, we can now calculate the theoretical yield of Li3N: 
0.0894 mol N2 x (2 mol Li3N / 1 mol N2) x (20.82 g Li3N / 1 mol Li3N) = 3.69 g Li3N 
Therefore, the theoretical yield of lithium nitride is 3.69 g. However, we need to round this to the correct number of significant figures in the given masses of reagents, which is 3. 
So, the answer is D) 4.18 g, which is the rounded value of the theoretical yield.

Lithium and Nitrogen React in a Combination Reaction to Produce