Chapter 10, Problem 30A

(a)

Interpretation Introduction

Interpretation: When 275g of sulfur is burned in excess oxygen the heat that is released to be calculated. 

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Concept introduction: The term $\text{U+PV}$ is known as enthalpy of the system. It is indicated by H. It performs total energy stored in the system. Thus,,

  $\text{H=U+PV}$

Here U, P and V are definite quantities.

Answer to Problem 30A

Thus, heat required to release when 275g of sulfur is burned in excess oxygen is -2538.5kJ.

Explanation of Solution

The given reaction is as follows:

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Molecular weight of sulfur is 32.065

Convert 275g sulfur to moles is as follows:

  $\frac{275}{32.065}=8.576\text{mol}$

Now calculation of heat is as follows:

  $\begin{array}{c}\Delta \text{H=8}\text{.576mol}\times \left(-296\text{kJ}/\text{mol}\right)\\ =-2538.5\text{kJ}\end{array}$

Thus, heat required to release when 275g of sulfur is burned in excess oxygen is -2538.5kJ.

(b)

Interpretation Introduction

Interpretation: When 25moles of sulfur is burned in excess oxygen the heat that is released to be calculated. 

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Concept introduction: The term $\text{U+PV}$ is known as enthalpy of the system. It is indicated by H. It performs total energy stored in the system. Thus,,

  $\text{H=U+PV}$

Here U, P and V are definite quantities.

Answer to Problem 30A

Heat required to release when 25mol of sulfur is burned in excess oxygen is -7400kJ.

Explanation of Solution

The given reaction is as follows:

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Now calculation of heat is as follows:

  $\begin{array}{c}\Delta \text{H=25mol}\times \left(-296\text{kJ}/\text{mol}\right)\\ =-7400\text{kJ}\end{array}$

Thus, heat required to release when 25mol of sulfur is burned in excess oxygen is -7400kJ.

(c)

Interpretation Introduction

Interpretation: When 150g of sulfur dioxide are produced the heat that is released to be calculated. 

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Concept introduction: The term $\text{U+PV}$ is known as enthalpy of the system. It is indicated by H. It performs total energy stored in the system. Thus,,

  $\text{H=U+PV}$

Here U, P and V are definite quantities.

Answer to Problem 30A

Thus, heat required to release when 150g of sulfur is burned in excess oxygen is -693.232kJ.

Explanation of Solution

The given reaction is as follows:

  $\text{S}\left(s\right)+{\text{O}}_{\text{2}}\left(g\right)\to {\text{SO}}_{\text{2}}\left(g\right)\Delta \text{H=}-29\text{6}\text{kJ}/\text{mol}$

Molecular weight of sulfur dioxide is $\text{32}.0\text{65}+2\times 15.994=64.053$

Convert 150g sulfur dioxide to moles is as follows:

  $\frac{150}{64.053}=2.342\text{mol}$

Now calculation of heat is as follows:

  $\begin{array}{c}\Delta \text{H=2}\text{.342mol}\times \left(-296\text{kJ}/\text{mol}\right)\\ =-693.232\text{kJ}\end{array}$

Thus, heat required to release when 150g of sulfur is burned in excess oxygen is -693.232kJ.