Chapter 10, Problem 150A

Interpretation Introduction

Interpretation:

The number of oxygen atoms present in 25.0 g of carbon dioxide should be calculated.

Concept introduction:

The number of moles of a compound is defined as the ratio of the given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 150A

Number of oxygen atoms = $6.84\times 10\text{atoms}$

Explanation of Solution

The given compound is carbon dioxide.

The molecular formula of carbon dioxide = ${\text{CO}}_2$

Molar mass of ${\text{CO}}_2$ = $1\left(12.01\text{ g/mole}\right)+2\left(15.999\text{ g/mole}\right)$

= $44.01\text{ g/mole}$

Mass of ${\text{CO}}_2$ = 25.0 g

Number of moles of ${\text{CO}}_2$ = $\frac{\text{25}\text{.0 g}}{\text{44}\text{.01 g/mole}}$

= $\text{0}\text{.568 mole}$

${\text{CO}}_2$ contains one mole of sodium and two moles of oxygen.

Number of moles of oxygen = $\text{0}\text{.568 mole}\times 2$

= $\text{1}\text{.136 mole}$

Number of oxygen atoms = $\text{Number of moles × 6}\text{.022}\times {\text{10}}^{23}\frac{\text{atoms}}{\text{mole}}$

= $\text{1}\text{.136 mole}\times \text{ 6}\text{.022}\times {\text{10}}^{23}\frac{\text{atoms}}{\text{mole}}$

Number of oxygen atoms = $6.84\times 10\text{atoms}$