Question

practice: 3. determine how many grams of hydrogen are needed to produce 28.65 g of ammonia in the following reaction: n₂(g) + 3h₂(g) → 2nh₃(g)

Explanation:

Step1: Calculate molar mass

The molar mass of $NH_3$ is $M_{NH_3}=14 + 3\times1= 17\ g/mol$. The molar mass of $H_2$ is $M_{H_2}=2\times1 = 2\ g/mol$.

Step2: Find moles of $NH_3$

The number of moles of $NH_3$, $n_{NH_3}=\frac{m_{NH_3}}{M_{NH_3}}=\frac{28.65\ g}{17\ g/mol}=1.685\ mol$.

Step3: Use mole - ratio

From the balanced chemical equation $N_2(g)+3H_2(g)\to2NH_3(g)$, the mole - ratio of $H_2$ to $NH_3$ is $\frac{n_{H_2}}{n_{NH_3}}=\frac{3}{2}$. So, $n_{H_2}=\frac{3}{2}n_{NH_3}$. Substituting $n_{NH_3} = 1.685\ mol$, we get $n_{H_2}=\frac{3}{2}\times1.685\ mol = 2.5275\ mol$.

Step4: Calculate mass of $H_2$

The mass of $H_2$, $m_{H_2}=n_{H_2}\times M_{H_2}=2.5275\ mol\times2\ g/mol = 5.055\ g$.

Answer:

$5.055\ g$