Chapter 4, Problem 27QP

(a)

Interpretation Introduction

Interpretation:

The molar mass of the compound given is to be calculated.

Explanation of Solution

The given compound is ${\text{Hg}}_2{\text{Cl}}_2$ . Molar mass can be determined by adding the masses of the component’s elements which are present in a chemical formula. Molar mass of ${\text{Hg}}_2{\text{Cl}}_2$ is calculated as follows:

The mass of $\text{Hg}$ from the periodic table is $200.6\text{ g/mole}$ . For $2\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{Hg}}=2\text{ mole}\times \text{200}\text{.6 g/mole}\\ =\text{401}\text{.2 g}\end{array}$

The mass of Chlorine from the periodic table is $35.45\text{ g/mole}$ . For $2\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{Cl}}=2\text{ mole}\times \text{35}\text{.45 g/mole}\\ =\text{70}\text{.90 g}\end{array}$

Therefore, the mass for $1\text{ mole}$ ${\text{Hg}}_2{\text{Cl}}_2$ is:

$\begin{array}{c}mas{s}_{{\text{Hg}}_2{\text{Cl}}_2}=401.2\text{ g}+70.90\text{ g}\\ =472.1\text{ g}\end{array}$

Hence, the molar mass of ${\text{Hg}}_2{\text{Cl}}_2$ is $\text{472}\text{.1 g/mole}$ .

(b)

Interpretation Introduction

Interpretation:

The molar mass of the substance is to be calculated.

Explanation of Solution

The given compound is ${\text{CaSO}}_4.2{\text{H}}_2\text{O}$ . Molar mass can be determined by adding the masses of the component’s elements which are present in a chemical formula. Molar mass of ${\text{CaSO}}_4.2{\text{H}}_2\text{O}$ is calculated as follows:

The mass of calcium from the periodic table is $40.08\text{ g/mole}$ . For $1\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{Ca}}=1\text{ mole}\times \text{40}\text{.08 g/mole}\\ =\text{40}\text{.08 g}\end{array}$

The mass of sulfur from the periodic table is $32.06\text{ g/mole}$ . For $1\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{S}}=1\text{ mole}\times \text{32}\text{.06 g/mole}\\ =\text{32}\text{.06 g}\end{array}$

The mass of oxygen from the periodic table is $16.00\text{ g/mole}$ . For $4\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{O}}=4\text{ mole}\times \text{16}\text{.00 g/mole}\\ =\text{64}\text{.00 g}\end{array}$

The mass of $1{\text{ mole H}}_2\text{O}$ is $18.016\text{ g/mole}$ . For $2\text{ mole}$ , the mass is:

$\begin{array}{l}=2\text{ mole}\times \text{18}\text{.016 g/mole}\\ =\text{36}\text{.032 g}\end{array}$

Therefore, the mass for $1\text{ mole}$ ${\text{CaSO}}_4.2{\text{H}}_2\text{O}$ is:

$\begin{array}{c}mas{s}_{{\text{CaSO}}_4.2{\text{H}}_2\text{O}}=40.08\text{ g}+32.06\text{ g}+\text{64}\text{.00 g}+36.032\text{ g}\\ =172.17\text{ g}\end{array}$

Hence, the molar mass of ${\text{CaSO}}_4.2{\text{H}}_2\text{O}$ is $172.17\text{ g/mol}$ .

(c)

Interpretation Introduction

Interpretation:

The molar mass of the substance is to be calculated.

Explanation of Solution

The given compound is ${\text{Cl}}_2{\text{O}}_5$ . Molar mass can be determined by adding the masses of the component’s elements which are present in a chemical formula. Molar mass of ${\text{Cl}}_2{\text{O}}_5$ is calculated as follows:

The mass of $\text{Cl}$ from the periodic table is $35.45\text{ g/mole}$ . For $2\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{Cl}}=2\text{ mole}\times \text{35}\text{.45 g/mole}\\ =\text{70}\text{.90 g}\end{array}$

The mass of $\text{O}$ from the periodic table is $16.00\text{ g/mole}$ . For $5\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{O}}=5\text{ mole}\times \text{16}\text{.00 g/mole}\\ =\text{80}\text{.00 g}\end{array}$

Therefore, the mass for $1\text{ mole}$ ${\text{Cl}}_2{\text{O}}_5$ is:

$\begin{array}{c}mas{s}_{{\text{Cl}}_2{\text{O}}_5}=70.90\text{ g}+80.00\text{ g}\\ =150.90\text{ g}\end{array}$

Hence, the molar mass of ${\text{Cl}}_2{\text{O}}_5$ is $\text{150}\text{.90 g/mole}$ .

(d)

Interpretation Introduction

Interpretation:

The molar mass of the substance is to be determined.

Explanation of Solution

The given compound is ${\text{NaHSO}}_4$ . Molar mass can be determined by adding the masses of the component’s elements which are present in a chemical formula. Molar mass of ${\text{NaHSO}}_4$ is calculated as follows:

The mass of $\text{Na}$ from the periodic table is $22.99\text{ g/mole}$ . For $1\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{Na}}=1\text{ mole}\times \text{22}\text{.99 g/mole}\\ =\text{22}\text{.99 g}\end{array}$

The mass of $\text{H}$ from the periodic table is $1.008\text{ g/mole}$ . For $1\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{H}}=1\text{ mole}\times \text{1}\text{.008 g/mole}\\ =\text{1}\text{.008 g}\end{array}$

The mass of sulfur from the periodic table is $32.06\text{ g/mole}$ . For $1\text{ mole}$ , the mass is:

$\begin{array}{l}=1\text{ mole}\times \text{32}\text{.06 g/mole}\\ =\text{32}\text{.06 g}\end{array}$

The mass of oxygen from the periodic table is $16.00\text{ g/mole}$ . For $4\text{ mole}$ , the mass is:

$\begin{array}{c}mas{s}_{\text{O}}=4\text{ mole}\times \text{16}\text{.00 g/mole}\\ =\text{64}\text{.00 g}\end{array}$

Therefore, the mass for $1\text{ mole}$ ${\text{NaHSO}}_4$ is:

$\begin{array}{c}mas{s}_{{\text{NaHSO}}_4}=22.99\text{ g}+1.008\text{ g}+\text{32}\text{.06 g}+64.00\text{ g}\\ =120.06\text{ g}\end{array}$

Hence, the molar mass of ${\text{NaHSO}}_4$ is $120.06\text{ g/mol}$ .