Chapter 2.7, Problem 3PPA

(a)

Interpretation Introduction

Interpretation:

The number of atoms should be calculated in 7.31 moles of potassium.

Concept introduction:

$\begin{array}{l}\text{Avogadro’s number is 6}{\text{.022 × 10}}^{\text{23}}\\ \text{1 mole = }\text{6}{\text{.022 × 10}}^{\text{23}}\text{Avogadro’s number }\end{array}$

$\text{mol × }\frac{\text{6}{\text{.022 × 10}}^{\text{23}}\text{ atoms}}{\text{1 mol }}\text{=}\text{ atoms}$

(b)

Interpretation Introduction

Interpretation:

The number of moles of potassium should be calculated in a sample containing $\text{8}{\text{.91 × 10}}^{\text{25}}$ K atoms.

Concept introduction:

$\begin{array}{l}\text{Avogadro’s number is 6}{\text{.022 × 10}}^{\text{23}}\\ \text{1 mole = }\text{6}{\text{.022 × 10}}^{\text{23}}\text{Avogadro’s number }\end{array}$

$\text{atoms × }\frac{\text{1 mol }}{\text{6}{\text{.022 × 10}}^{\text{23}}\text{ atoms}}\text{=}\text{mol}$