Chapter 9, Problem 15A

(a)

Interpretation Introduction

Interpretation: The mass in grams in $\text{2}\text{.21 }\times {\text{10}}^{\text{-4}}$ moles of calcium carbonate needs to be calculated.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

  $\text{2}{\text{.21 ×10}}^{\text{-2}}\text{ g}$

Explanation of Solution

Molar mass of calcium carbonate = 100 g/mol

Moles of calcium carbonate= $\text{2}\text{.21 }\times {\text{10}}^{\text{-4}}$

Thus, there are 100 g in 1 mol.

Calculate mass in grams:

  $\text{2}{\text{.21 ×10}}^{\text{-4}}\text{moles ×}\frac{\text{100 g}}{\text{1 mole}}\text{ = 2}{\text{.21 ×10}}^{\text{-2}}\text{ g}$

(b)

Interpretation Introduction

Interpretation: The mass in grams in 2.75 moles of Helium needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

  $\text{ 11}\text{.0 g}$

Explanation of Solution

Molar mass of Helium = 4.00 g/mol

Moles of Helium = 2.75 moles

Thus, 1 mol of He has 4.00 g.

Calculate mass in grams:

  $\text{2}\text{.75 moles ×}\frac{\text{4}\text{.00 g}}{\text{1 mole}}\text{ = 11}\text{.0 g}$

(c)

Interpretation Introduction

Interpretation: The mass in grams in 0.00975 moles of oxygen gas needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

  $\text{0}\text{.312 g}$

Explanation of Solution

Molar mass of oxygen gas = 32.0 g/mol

Moles of oxygen gas = 0.00975 moles

Thus, 1 mol of oxygen gas has 32 g.

Calculate mass in grams:

  $\text{0}\text{.00975 moles ×}\frac{\text{32}\text{.0 g}}{\text{1 mole}}\text{ = 0}\text{.312 g}$

(d)

Interpretation Introduction

Interpretation: The mass in grams in $\text{7}\text{.21 }\times {\text{10}}^{\text{-3}}$ moles of carbon dioxide needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

  ${\text{317×10}}^{\text{-3}}\text{g}$

Explanation of Solution

Molar mass of carbon dioxide = 44.0 g/mol

Moles of carbon dioxide = $\text{7}\text{.21 }\times {\text{10}}^{\text{-3}}$ moles

1 mol of carbon dioxide has 44 g.

Calculate mass in grams:

  $\text{7}{\text{.21 ×10}}^{\text{-3}}\text{moles ×}\frac{\text{44}\text{.0 g}}{\text{1 mole}}{\text{ = 317×10}}^{\text{-3}}\text{g}$

(e)

Interpretation Introduction

Interpretation: The mass in grams in 0.835 moles of iron (II) sulphide needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

Mass = $\text{73}\text{.4 g}$

Explanation of Solution

Molar mass of iron (II) sulfide= 87.9 g/mol

Moles of iron (II) sulfide= 0.835 moles

Thus, 1 mol of iron sulphide has 87.9 g.

Calculate mass in grams:

  $\text{0}\text{.835 moles ×}\frac{\text{87}\text{.9 g}}{\text{1 mole}}\text{ = 73}\text{.4 g}$

(f)

Interpretation Introduction

Interpretation: The mass in grams in 4.01 moles of potassium hydroxide needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

Mass = 225 g

Explanation of Solution

Molar mass of potassium hydroxide= 56.1 g/mol

Moles of potassium hydroxide= 4.01 moles

1 mol of potassium hydroxide has 56.1 g.

Calculate mass in grams:

  $\text{4}\text{.01 moles ×}\frac{\text{56}\text{.1 g}}{\text{1 mole}}\text{ = 225 g}$

(g)

Interpretation Introduction

Interpretation: The mass in grams in 0.0219 moles of hydrogen gas needs to be determined.

Concept Introduction: The molecular mass of compound is the sum of atomic mass of all the atoms present in the given chemical compound. Mole concept is used to calculate the moles, mass, number of atoms and moles of a compound. The relation between these values can be shown as:

  $\begin{array}{l}\text{Moles = }\frac{\text{mass}}{\text{molar mass}}\\ {\text{1 mole = N}}_{\text{a}}\text{ atoms}\\ {\text{N}}_{\text{a}}\text{ = 6}\text{.022 }\times {\text{ 10}}^{\text{23}}\end{array}$

Answer to Problem 15A

Mass = $\text{0}\text{.044 g}$

Explanation of Solution

Molar mass of hydrogen gas = 2.01 g/mol

Moles of hydrogen gas= 0.0219 moles

1 mole of hydrogen gas has 2.01 g.

Calculate mass in grams:

  $\text{0}\text{.0219 moles ×}\frac{\text{2}\text{.01 g}}{\text{1 mole}}\text{ = 0}\text{.044 g}$