Chapter 10, Problem 131A

Interpretation Introduction

(a)

Interpretation:

The molar mass of nitric acid ( ${\text{HNO}}_{\text{3}}$ ) should be calculated.

Concept introduction:

The number of moles of a compound is defined as the ratio of the given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 131A

Molar mass of ${\text{HNO}}_{\text{3}}$ = $63.0\text{ g/mole}$

Explanation of Solution

The given compound is nitric acid having molecular formula ${\text{HNO}}_{\text{3}}$.

The molar mass of the compound is equal to the sum of atomic masses of all atoms present in the compound in gram/mole.

To find the molar mass of the compound, multiply the molecular weight of the atom by the corresponding subscript number.

Molar mass of nitrogen = 14.0067 g/mole

Molar mass of hydrogen = 1.00784 g/mole

Molar mass of oxygen = 15.999 g/mole

Molar mass of ${\text{HNO}}_{\text{3}}$

= $\text{1}\left(\text{1}\text{.00784 g/mole}\right)\text{ +1}\left(14.0067\text{ g/mole}\right)+3\left(15.999\text{ g/mole}\right)$

= $63.0\text{ g/mole}$

Interpretation Introduction

(b)

Interpretation:

The molar mass of ammonium nitrate ( ${\text{NH}}_4{\text{NO}}_{\text{3}}$ ) should be calculated.

Concept introduction:

The number of moles of a compound is defined as the ratio of the given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 131A

Molar mass of ${\text{NH}}_4{\text{NO}}_{\text{3}}$ = $80.1\text{ g/mole}$

Explanation of Solution

The given compound is ammonium nitrate having molecular formula ${\text{NH}}_4{\text{NO}}_{\text{3}}$.

The molar mass of the compound is equal to the sum of atomic masses of all atoms present in the compound in gram/mole.

To find the molar mass of the compound, multiply the molecular weight of the atom by the corresponding subscript number.

Molar mass of nitrogen = 14.0067 g/mole

Molar mass of hydrogen = 1.00784 g/mole

Molar mass of oxygen = 15.999 g/mole

Molar mass of ${\text{NH}}_4{\text{NO}}_{\text{3}}$

= $4\left(\text{1}\text{.00784 g/mole}\right)\text{ +2}\left(14.0067\text{ g/mole}\right)+3\left(15.999\text{ g/mole}\right)$

= $80.1\text{ g/mole}$

Interpretation Introduction

(c)

Interpretation:

The molar mass of zinc oxide ( $\text{ZnO}$ ) should be calculated.

Concept introduction:

The number of moles of a compound is defined as the ratio of the given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 131A

Molar mass of $\text{ZnO}$ = $81.4\text{ g/mole}$

Explanation of Solution

The given compound is zinc oxide having molecular formula $\text{ZnO}$.

The molar mass of the compound is equal to the sum of atomic masses of all atoms present in the compound in gram/mole.

To find the molar mass of the compound, multiply the molecular weight of the atom by the corresponding subscript number.

Molar mass of zinc = 65.38 g/mole

Molar mass of oxygen = 15.999 g/mole

Molar mass of $\text{ZnO}$

= $1\left(65.38\text{ g/mole}\right)+1\left(15.999\text{ g/mole}\right)$

= $81.4\text{ g/mole}$

Interpretation Introduction

(d)

Interpretation:

The molar mass of cobalt chloride ( ${\text{CoCl}}_2$ ) should be calculated.

Concept introduction:

The number of moles of a compound is defined as the ratio of the given mass of the compound to the molar or molecular mass of the compound.

The mathematical expression is given by:

Number of moles = $\frac{\text{given mass of the compound}}{\text{molar mass of the compound}}$

The one mole of any substance is equal to the Avogadro number, i.e., $6.022\times {10}^{23}$ atoms.

Answer to Problem 131A

Molar mass of $\text{CoCl}$ = $129.83\text{ g/mole}$

Explanation of Solution

The given compound is cobalt chloride having molecular formula $\text{CoCl}$.

The molar mass of the compound is equal to the sum of atomic masses of all atoms present in the compound in gram/mole.

To find the molar mass of the compound, multiply the molecular weight of the atom by the corresponding subscript number.

Molar mass of cobalt = 58.93 g/mole

Molar mass of chlorine = 35.45 g/mole

Molar mass of $\text{CoCl}$

= $1\left(58.93\text{ g/mole}\right)+2\left(35.45\text{ g/mole}\right)$

= $129.83\text{ g/mole}$