Limiting Reactant Chemistry Example 4

Follow the full solution, then compare it with the other examples linked below.

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In the reaction

\text{N}_2 + 3\text{H}_2 \rightarrow 2\text{NH}_3

, if you have

2.0

mol of

\text{N}_2

and

5.0

mol of

\text{H}_2

, which reactant is limiting and how many moles of

\text{NH}_3

can form?

1
For $2.0$ mol $\text{N}_2$ , you would need $3 \times 2.0 = 6.0$ mol $\text{H}_2$ , but only $5.0$ mol are available, so $\text{H}_2$ is limiting.
2
Use the ratio $3$ mol $\text{H}_2 \rightarrow 2$ mol $\text{NH}_3$ : $5.0 \times \frac{2}{3} = 3.33\,\text{mol } \text{NH}_3$ .

Answer

\text{H}_2\text{ is limiting; } 3.33\,\text{mol } \text{NH}_3

The limiting reactant is the one that runs out first. Once you identify it, use only that reactant to calculate the maximum product.

About Limiting Reactant

The reactant that is completely consumed first in a chemical reaction, thereby determining the maximum amount of product that can be formed.

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