Question

The equation below shows lithium reacting with nitrogen to produce lithium nitride:
6Li+N
2
​
→2Li
3
​
N

If 12 mol of lithium were reacted with excess nitrogen gas, how many moles of lithium nitride would be produced?
A. 4.0 mol
B. 6.0 mol
C. 12 mol
D. 36 mol

Answer 1

To determine how many moles of lithium nitride (Li₃N) would be produced from 12 moles of lithium (Li) reacting with excess nitrogen, we can use the balanced chemical equation:

\[ 6Li + N_2 → 2Li_3N \]

From the equation, we can see that:

- 6 moles of lithium produce 2 moles of lithium nitride.

Now, to find out how much lithium nitride is produced from 12 moles of lithium, we can set up a ratio based on the coefficients from the balanced equation:

\[
\text{If } 6 \text{ moles of Li produce } 2 \text{ moles of Li}_3N:
\]

\[
12 \text{ moles of Li will produce } x \text{ moles of Li}_3N.
\]

Using the ratio:

\[
\frac{2 \text{ moles of Li}_3N}{6 \text{ moles of Li}} = \frac{x \text{ moles of Li}_3N}{12 \text{ moles of Li}}
\]

Cross-multiplying gives:

\[
x \cdot 6 = 2 \cdot 12
\]

\[
6x = 24
\]

Dividing both sides by 6:

\[
x = 4
\]

So, 12 moles of lithium will produce **4.0 moles of lithium nitride**.

The correct answer is: **A. 4.0 mol**.