Chapter 3, Problem 3.1P

The atomic mass of Cl is 35.45 amu, and the atomic mass of Al is 26.98 amu. What are the masses in grams of 3 mol of Al atoms and of 2 mol of Cl atoms?

Interpretation Introduction

Interpretation:Mass in grams for $\text{3 mol Al}$ and $\text{2 mol Cl}$ atoms is to be calculated.

Concept introduction:The formula to convert moles to mass in grams is as follows:

  $\text{Mass}=\left(\text{Number of moles}\right)\left(\text{molar mass}\right)$

The units of mass are grams derived as follows:

  $\begin{array}{c}\text{Mass}=\left(\text{mol}\right)\left(\frac{\text{g}}{\text{mol}}\right)\\ =\left(\text{g}\right)\end{array}$

Answer to Problem 3.1P

Mass in grams for $\text{3 mol Al}$ and $\text{2 mol Cl}$ atoms is $80.94\text{ g}$ and $70.9\text{ g}$ respectively.

Explanation of Solution

Given Information:

Moles of aluminum is given as $\text{3 mol}$ , atomic mass of $\text{Al}$ is $\text{26}\text{.98 g/mol}$ . Moles of $\text{Cl}$ is $\text{2 mol}$ and atomic mass of $\text{Cl}$ is $\text{35}\text{.45 g/mol}$ .

The formula to convert moles to mass in grams is as follows:

  $\text{Mass}=\left(\text{Number of moles}\right)\left(\text{molar mass}\right)$

Moles of aluminum is givenas $\text{3 mol}$ .

Molar mass of $\text{Al}$ is $\text{26}\text{.98 g/mol}$ .

Substitute the values in above formula to calculate mass of $\text{Al}$ .

  $\begin{array}{c}\text{Mass}=\left(\text{Number of moles}\right)\left(\text{molar mass}\right)\\ =\left(\text{3 mol}\right)\left(\text{26}\text{.98 g/mol}\right)\\ =80.94\text{ g}\end{array}$

Moles of $\text{Cl}$ is $\text{2 mol}$ .

Atomic mass of $\text{Cl}$ is $\text{35}\text{.45 g/mol}$ .

Substitute the values in above formula to calculate mass of $\text{Cl}$ .

  $\begin{array}{c}\text{Mass}=\left(\text{Number of moles}\right)\left(\text{molar mass}\right)\\ =\left(\text{2 mol}\right)\left(\text{35}\text{.45 g/mol}\right)\\ =70.9\text{ g}\end{array}$