Chapter 15, Problem 105A

Interpretation Introduction

Interpretation: To determine the amount of hydrogen gas and oxygen gas to produce $4.50\text{ mol}$ of water.

Concept Introduction: Mole can be defined as the ratio of mass and molar mass of the compound.

Answer to Problem 105A

The mass of hydrogen gas required is 9 g and the mass of oxygen is 72 g.

Explanation of Solution

According to the balanced equation,

  ${\text{H}}_{\text{2}}\left(\text{g}\right)+\frac{\text{1}}{\text{2}}{\text{O}}_{\text{2}}\left(\text{g}\right)\to {\text{H}}_{\text{2}}\text{O}\left(\text{g}\right)$

1 mole of hydrogen combines with $\frac{1}{2}$ mole of oxygen to form 1 moles of water.

So, 4.5 moles of hydrogen gas react with 2.25 moles of oxygen to form 4.5 moles of water.

The mass of a hydrogen atom can be determined by using the formula:

  $\begin{array}{l}\begin{array}{c}\text{mass of hydrogen = }\frac{\text{mass}}{\text{molar}\text{mass}}\\ \text{Mass}\text{= moles×molar}\text{mass }\\ \text{=4}\text{.5×2}\\ \text{=9}\text{gram }\end{array}\hfill \end{array}$

Mass of the oxygen atom can be determined by using the formula:

  $\begin{array}{c}\text{Moles}\text{of}\text{}\text{oxygen=}\frac{\text{mass}}{\text{molar}\text{mass}}\\ \text{mass=}\text{moles×molar}\text{mass}\\ \text{Mass}\text{=2}\text{.25}\text{moles×32}\\ \text{Mass=}\text{72}\text{gram}\end{array}$

Therefore, the mass of hydrogen gas required is 9 g and the mass of oxygen is 72 g.