Chapter 10.2, Problem 24LC

Interpretation Introduction

Interpretation: The conversion between mass and the number of moles of a substance should be explained.

Concept Introduction: Factor that uses one set of units to change it to another set of units is said to be conversion factor.

Explanation of Solution

For converting the mass of a substance to its number of moles, the molar mass of the substance is used. The conversion factor used is:

  $\text{mass of a substance in g × molar mass of substance in g/mol = mol of the substance}$

For example, the number of moles in $200\text{ g}$ of ${\text{C}}_{\text{2}}{\text{H}}_{\text{6}}\text{O}$ (having molar mass, 46.0 g/mol) is:

  $200.0\text{ g}\times \frac{1\text{ mol}}{46.0\text{ g}}\text{ = 4}\text{.35 mol}$