Chapter 3, Problem 3.12P

(a)

Interpretation Introduction

Interpretation:

The mass of $0.346\text{ mol}$ of $\text{Zn}$ in grams is to be calculated.

Concept introduction:

The atomic mass of an element is expressed in $\text{amu}$ which is numerically equivalent to the mass of $\text{1 mol}$ of that element expressed in grams.

The mass of each element in grams can be calculated from the given moles and the molar mass of the element. The expression to calculate the mass of an element in grams is as follows:

$\text{Mass }\left(\text{g}\right)=\left(\text{amount}\left(\text{mol}\right)\right)\left(\frac{\text{no}\text{. of grams}}{1\text{ mol}}\right)$

(b)

Interpretation Introduction

Interpretation:

The number of $\text{F}$ atoms in $\text{2}\text{.62 mol}$ of ${\text{F}}_2$ is to be determined.

Concept introduction:

One mole is defined as the amount of substance that contains the same number of entities such as molecules, ions, atoms as the number of atoms in $12\text{ g}$ of $\text{C-12}$. This number is called Avogadro’s number. The value of Avogadro’s number is $\text{6}\text{.022}\times {\text{10}}^{23}\left(\text{entitites/mol}\right)$.

The number of atoms of an element is calculated by converting the moles to molecules by using Avogadro’s number and then multiplying the resultant molecules to the number of atoms of that element in a molecule.

(c)

Interpretation Introduction

Interpretation:

The number of $\text{Ca}$ atoms in $\text{28}\text{.5 g}$ of $\text{Ca}$ is to be determined.

Concept introduction:

One mole is defined as the amount of substance that contains the same number of entities such as molecules, ions, atoms as the number of atoms in $12\text{ g}$ of $\text{C-12}$. This number is called Avogadro’s number. The value of Avogadro’s number is $\text{6}\text{.022}\times {\text{10}}^{23}\left(\text{entitites/mol}\right)$.

The number of atoms of an element is calculated by converting the mass to moles by multiplying with the molar mass and then converting mole to atoms by using Avogadro’s number. Following is the expression to calculate the number of atoms when the mass of the chemical substance is given,

$\text{Number of atoms}=\left(\text{given mass}\left(\text{g}\right)\right)\left(\frac{1\text{ mol}}{\text{no}\text{.of grams }}\right)\left(\frac{6.022\times {10}^{23}\text{ atoms}}{1\text{ mol}}\right)$