Chapter 9, Problem 14A

(a)

Interpretation Introduction

Interpretation:

The mass of calcium carbonate in samples needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of calcium carbonate is 0.0221 g.

Explanation of Solution

Moles of calcium carbonate = 2.21 × 10-4 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}{\text{CaCO}}_{\text{3}}\text{=}\frac{\text{mass}\text{of}{\text{CaCO}}_{\text{3}}}{\text{molar}\text{mass}\text{of}{\text{CaCO}}_{\text{3}}}\\ \text{mass}\text{of}{\text{CaCO}}_{\text{3}}\text{=}\text{moles}\text{of}{\text{CaCO}}_{\text{3}}\text{×}\text{molar}\text{mass}\text{o0f}{\text{CaCO}}_{\text{3}}\\ \text{=}\text{2}\text{.21}\text{×}{\text{10}}^{\text{-4}}\text{mol}\text{×}\text{100}\text{.0869}{\text{gmol}}^{\text{-1}}\\ \text{=}0.0221\text{g}\end{array}$

(b)

Interpretation Introduction

Interpretation:

The mass in grams of helium needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of helium = 11.007 g

Explanation of Solution

Moles of helium = 2.75 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}\text{He}\text{=}\frac{\text{mass}\text{of}\text{He}}{\text{molar}\text{mass}\text{of}\text{He}}\\ \text{mass}\text{of}\text{He}\text{=}\text{moles}\text{of}\text{He}\text{×}\text{molar}\text{mass}\text{of}\text{He}\\ \text{=}\text{2}\text{.75}\text{mol}\text{×}\text{4}\text{.002602}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{11}\text{.007g}\end{array}$

(c)

Interpretation Introduction

Interpretation:

The mass in grams of the oxygen gas needs to be determined.

.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of oxygen gas = 0.3119 g

Explanation of Solution

Moles of oxygen gas = 0.00975 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}\text{oxygen}\text{gas}\text{=}\frac{\text{mass}\text{of}\text{oxygen}\text{gas}}{\text{molar}\text{mass}\text{of}\text{oxygen}\text{gas}}\\ \text{mass}\text{of}\text{oxygen}\text{gas}\text{=}\text{moles}\text{of}\text{oxygen}\text{gas}\text{×}\text{molar}\text{mass}\text{of}\text{oxygen}\text{gas}\\ \text{=}\text{0}\text{.00975}\text{mol}\text{×}\text{31}\text{.999}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{0}\text{.3119}\text{g}\end{array}$

(d)

Interpretation Introduction

Interpretation:

The mass of carbon dioxide needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of carbon dioxide = 0.317 g

Explanation of Solution

Moles of carbon dioxide = 7.21× 10-3 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}{\text{CO}}_{\text{2}}\text{=}\frac{\text{mass}\text{of}{\text{CO}}_{\text{2}}}{\text{molar}\text{mass}\text{of}{\text{CO}}_{\text{2}}}\\ \text{mass}\text{of}{\text{CO}}_{\text{2}}\text{=}\text{moles}\text{of}{\text{CO}}_{\text{2}}\text{×}\text{molar}\text{mass}\text{of}{\text{CO}}_{\text{2}}\\ \text{=}\text{7}\text{.21}\text{×}{\text{10}}^{\text{-3}}\text{mol}\text{×}\text{44}\text{.01}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{0}\text{.317}\text{g}\end{array}$

(e)

Interpretation Introduction

Interpretation:

The mass of iron sulfide needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of iron (II) sulfide = 73.413 g

Explanation of Solution

Moles of iron (II) sulfide = 0.835 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}\text{=}\frac{\text{mass}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}}{\text{molar}\text{mass}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}}\\ \text{mass}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}\text{=}\text{moles}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}\text{×}\text{molar}\text{mass}\text{of}\text{iron}\left(\text{II}\right)\text{sulfide}\\ \text{=}\text{0}\text{.835mol}\text{×}\text{87}\text{.92}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{73}\text{.413}\text{g}\end{array}$

(f)

Interpretation Introduction

Interpretation:

The mass in grams of potassium hydroxide needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of potassium hydroxide = 224.98 g

Explanation of Solution

Moles of potassium hydroxide = 4.01 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}\text{KOH}\text{=}\frac{\text{mass}\text{of}\text{KOH}}{\text{molar}\text{mass}\text{of}\text{KOH}}\\ \text{mass}\text{of}\text{KOH}\text{=}\text{moles}\text{of}\text{KOH}\text{×}\text{molar}\text{mass}\text{of}\text{KOH}\\ \text{=}\text{4}\text{.01mol}\text{×}\text{56}\text{.1056}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{224}\text{.98}\text{g}\end{array}$

(g)

Interpretation Introduction

Interpretation:

The mass of hydrogen gas needs to be determined.

Concept Introduction:

Mole is the amount of the substance that contains the same number of particles or atoms or molecules. Molar mass is defined as an average mass of atoms present in the chemical formula. It is the sum of the atomic masses of all the atoms present in the chemical formula of any compound.

Answer to Problem 14A

Mass of hydrogen gas =0.0441 g

Explanation of Solution

Moles of hydrogen gas = 0.0219 mol

The calculation of mass is shown below:

  $\begin{array}{c}\text{moles}\text{of}\text{hydrogen}\text{gas}\text{=}\frac{\text{mass}\text{of}\text{hydrogen}\text{gas}}{\text{molar}\text{mass}\text{of}\text{hydrogen}\text{gas}}\\ \text{mass}\text{of}\text{hydrogen}\text{gas}\text{=}\text{moles}\text{of}\text{hydrogen}\text{gas}\text{×}\text{molar}\text{mass}\text{of}\text{hydrogen}\text{gas}\\ \text{=}\text{0}\text{.0219}\text{mol}\text{×}\text{2}\text{.01588}{\text{gmol}}^{\text{-1}}\\ \text{=}\text{0}\text{.0441}\text{g}\end{array}$