Chapter 9.2, Problem 4RQ

(a)

Interpretation Introduction

Interpretation :

Mass of hydrogen gas required to react completely with 10 g of nitrogen must be calculated.

Concept Introduction :

1 mol nitrogen gas (28 g) needs 3 moles of hydrogen gas (6 g) to produce 2 moles of ammonia gas (34 g).

Answer to Problem 4RQ

Mass of hydrogen gas is 2.14 g which is required to react completely with 10 g of nitrogen gas.

Explanation of Solution

The chemical reaction between nitrogen and hydrogen gas to form ammonia gas is as follows:

  ${\text{N}}_{\text{2}}{\text{(g)+3H}}_{\text{2}}\text{(g)}\to {\text{2NH}}_{\text{3}}\text{(g)}\text{.}$

As per the balanced chemical equation,

1 mol of nitrogen gas reacts with 3 mol of hydrogen gas. Molar mass of nitrogen is 28 g/mol and that of hydrogen gas is 2 g/mol thus, it can be said that:

28 g nitrogen needs 6 g hydrogen.

Or,

1 g nitrogen needs $\frac{\text{6}}{\text{28}}\text{ g}$ hydrogen.

Thus 10 g nitrogen needs $\frac{\text{6}\times \text{10}}{\text{28}}\text{ g=}\frac{\text{60}}{\text{28}}\text{ g=2}\text{.14 g}$ hydrogen.

b)

Interpretation Introduction

Interpretation :

Mass of ammonia gas which will be produced from 10 g nitrogen gas and sufficient hydrogen gas must be calculated.

Concept Introduction :

Nitrogen gas is limiting reagent as hydrogen gas is added in sufficient amount.

1 mol nitrogen gas (28 g) produces 2 moles of ammonia gas (34 g).

Answer to Problem 4RQ

12.14 g ammonia gas is produced from 10 g nitrogen gas and sufficient hydrogen gas.

Explanation of Solution

The chemical reaction between nitrogen and hydrogen gas to form ammonia gas is as follows:

  ${\text{N}}_{\text{2}}{\text{(g)+3H}}_{\text{2}}\text{(g)}\to {\text{2NH}}_{\text{3}}\text{(g)}\text{.}$

The molar mass of ammonia is 17 g/mol.

As per balanced equation 28 g nitrogen gas produces 34 g ammonia gas.

1 g nitrogen gas produces $\frac{34}{\text{28}}\text{ g}$ ammonia gas.

Thus 10 g nitrogen gas produces $\frac{34\times 10}{\text{28}}\text{ g=}\frac{\text{340}}{\text{28}}\text{ g =12}\text{.14 g}$ ammonia gas.