Chapter 10, Problem 30A

(a)

Interpretation Introduction

Interpretation:

When 275 g of sulfur is burned in excess of oxygen, the heat evolved for the given reaction needs to be calculated.

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 30A

Heat evolved = 2536.72 kJ

Explanation of Solution

The given reaction is shown below:

  ${\text{ S}}_{\left(\text{s}\right)}\text{+}{\text{O}}_{\text{2}\left(\text{g}\right)}\to {\text{SO}}_{\text{2}\left(\text{g}\right)}{\text{ΔH = -296 kJmol}}^{\text{-1}}$

The calculation of moles is shown below:

  $\begin{array}{l}\text{Moles of sulfur =}\frac{\text{ Mass}\text{of}\text{sulfur}}{\text{molar}\text{mass}\text{of}\text{sulfur}}\hfill \\ \text{ =}\frac{\text{275 g}}{\text{32}{\text{.06 gmol}}^{-1}}\hfill \\ \text{ =}\text{8}\text{.57 moles}\hfill \end{array}$

The calculation of heat evolved is shown below:

  $\begin{array}{l}\text{Heat evolved = 8}\text{.57 moles × }\left({\text{296 kJmol}}^{\text{-1}}\right)\hfill \\ \text{ = 2536}\text{.72 kJ}\hfill \end{array}$

(b)

Interpretation Introduction

Interpretation:

When 25 mol of sulfur is burned in excess oxygen, the heat evolved for the given reaction needs to be determined.

Concept Introduction:

Heat is evolved in the exothermic reaction whereas heat is absorbed in the endothermic reaction.

Answer to Problem 30A

Heat evolved = 7400 kJ

Explanation of Solution

The given reaction is shown below:

  ${\text{ S}}_{\left(\text{s}\right)}\text{+}{\text{O}}_{\text{2}\left(\text{g}\right)}\to {\text{SO}}_{\text{2}\left(\text{g}\right)}{\text{ΔH = -296 kJmol}}^{\text{-1}}$

The calculation of heat evolved is shown below:

  $\begin{array}{l}\text{Heat evolved = 25 moles × }\left({\text{296 kJmol}}^{\text{-1}}\right)\hfill \\ \text{ =7400 kJ}\hfill \end{array}$

(c)

Interpretation Introduction

Interpretation:

When 150 g of sulfur dioxide is produces, the heat evolved for the given reaction 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 30A

Heat evolved = 692.64 kJ

Explanation of Solution

The given reaction is shown below:

  ${\text{ S}}_{\left(\text{s}\right)}\text{+}{\text{O}}_{\text{2}\left(\text{g}\right)}\to {\text{SO}}_{\text{2}\left(\text{g}\right)}{\text{ΔH = -296 kJmol}}^{\text{-1}}$

The calculation of moles is shown below:

  $\begin{array}{l}\begin{array}{l}\text{Moles of sulfur dioxide =}\frac{\text{mass}\text{of}\text{sulfur}\text{dioxide}}{\text{molar}\text{mass}\text{of}\text{sulfur}\text{dioxide}}\\ \text{ =}\frac{\text{150 g}}{\text{ 64}{\text{.07 gmol}}^{\text{-1}}}\end{array}\hfill \\ \text{ = 2}\text{.34 moles}\hfill \end{array}$

The calculation of heat evolved is shown below:

  $\begin{array}{l}\text{Heat evolved = 2}\text{.34 moles × }\left({\text{ 296 kJmol}}^{\text{-1}}\right)\hfill \\ \text{ = 692}\text{.64 kJ}\hfill \end{array}$