Chapter 10.1, Problem 4PP

Interpretation Introduction

Interpretation:

The number of oxygen atoms in 5.0 mol of O₂ molecule needs to be determined.

Concept introduction:

In 1 mol of any substance, there are $6.022\times {10}^{23}$ units of that substance. These units can be atoms and molecules. The number of units in 1 mol of any substance is known as Avogadro’s number. It is denoted by symbol N_A.

Answer to Problem 4PP

The number of O atoms is $6.022\times {10}^{24}$.

Explanation of Solution

Given information:

The number of moles of O₂ molecule is 5.0 mol.

Calculation:

To calculate the number of O atoms, first calculate the number of moles of O atoms from number of moles of O₂ molecule.

Since oxygen molecule is diatomic, 1 mol of O₂ molecules contains 2 mol of O atoms. Thus, the number of moles of O atom in 5.0 mol of O₂ will be 10 mol.

The number of moles can be converted into number of units using the following conversion factor:

$\begin{array}{l}1{\text{ mole = N}}_{\text{A}}\\ \text{1 mole = 6}\text{.022}\times {\text{ 10}}^{23}\text{ units}\end{array}$

Thus, in 10 mol, the number of O atoms can be calculated as follows:

$N=n\times N_A$

Putting the values,

$\begin{array}{l}N=\left(10\text{ mol}\right)\left(6.022\times {10}^{23}\text{ atoms/mol}\right)\\ =6.022\times {10}^{24}\text{ atoms}\end{array}$

Conclusion

Thus, in 5 mol of O₂, there are $6.022\times {10}^{24}$ atoms of O.