 Chemistry & Chemical Reactivity
10th Edition
ISBN: 9781337399074
Author: John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher: Cengage Learning  Chemistry & Chemical Reactivity
Principles Of Chemical Reactivity: Energy And Chemical Reactions. 58PS

# The enthalpy change for the formation the following reaction has to be determined. Concept Introduction: If a reaction proceeds in two or more other reaction, Δ r H 0 for the overall process is the sum of Δ r H 0 values of all those reactions-Hess’s law. The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as: Δ r H= enthalpy change number of moles Δ r H= Δ H number of moles

Question Chapter 5, Problem 58PS

(a)

Interpretation Introduction

## Interpretation:The enthalpy change for the formation the following reaction has to be determined.Concept Introduction:If a reaction proceeds in two or more other reaction,ΔrH0 for the overall process is the sum of ΔrH0 values of all those reactions-Hess’s law.The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as:  ΔrH=enthalpy changenumber of moles   ΔrH=ΔHnumber of moles

(a)

Expert Solution

The enthalpy change for the formation is -4.6kJ

### Explanation of Solution

Given mass is 1.0g

The enthalpy of formation is  -296.8 KJ/Mol

S+O2SO2  ΔfH0= -296.8 KJ/Mol

The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as:

ΔrH=enthalpy changenumber of moles

ΔrH=ΔHnumber of moles

ΔrH=1.0g(1mol÷64.066 g)(-296.8kJ/mol÷1mol) =-4.6kJ

So, the enthalpy change for the formation is -4.6kJ

(b)

Interpretation Introduction

### Interpretation:The enthalpy change for the formation the following reaction has to be determined.Concept Introduction:If a reaction proceeds in two or more other reaction,ΔrH0 for the overall process is the sum of ΔrH0 values of all those reactions-Hess’s law.

(b)

Expert Solution

The enthalpy change for the formation is 18.14kJ

### Explanation of Solution

Given mass is 0.20mol

The enthalpy of formation is 90.7kJ

HgO2Hg+O2  ΔfH0= 90.7kJ

The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as:

ΔrH=enthalpy changenumber of moles

ΔrH=ΔHnumber of moles

ΔfH0= 90.7kJ/mol (reverse rxn)

(90.7kJ1mol)(0.20mol) =18.14kJ

So, the change in enthalpy is 18.14kJ

(c)

Interpretation Introduction

### Interpretation:The enthalpy change for the formation the following reaction has to be determined.Concept Introduction:If a reaction proceeds in two or more other reaction,ΔrH0 for the overall process is the sum of ΔrH0 values of all those reactions-Hess’s law

(c)

Expert Solution

The change in enthalpy is -7.3kJ

### Explanation of Solution

Given mass is 2.4g

The enthalpy of formation is ΔfH0=-411.12kJ/mol

2Na +Cl2NaCl  ΔfH0=-411.12kJ/mol

The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as:

ΔrH=enthalpy changenumber of moles

ΔrH=ΔHnumber of moles

ΔfH0=-46.0 kJ/mol

2.40g×1mol15.01464g=0.159mol

Energy change = -46.0 kJ/mol×0.159mol=-7.3kJ

So, the change in enthalpy is -7.3kJ

(d)

Interpretation Introduction

### Interpretation:The enthalpy change for the formation the following reaction has to be determined.Concept Introduction:If a reaction proceeds in two or more other reaction,ΔrH0 for the overall process is the sum of ΔrH0 values of all those reactions-Hess’s law.

(d)

Expert Solution

The change in enthalpy is -4.13 kJ

### Explanation of Solution

Given mass is 1.05×10-2mol

The enthalpy of formation is ΔfH0=-393.5 kJ/mol

C +O2CO2  ΔfH0=-393.5 kJ/mol

The change in enthalpy, ΔH in kJ per mole of a given reactant for the reaction can be calculated as:

ΔrH=enthalpy changenumber of moles

ΔrH=ΔHnumber of moles

ΔfH0=-393.5 kJ/mol

Energy change =(-393.5 kJ/mol 1mol)(1.05×10-2mol)=-4.13 kJ

So, the change in enthalpy is -4.13 kJ

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10th Edition
ISBN: 9781337399074
Author: John C. Kotz, Paul M. Treichel, John Townsend, David Treichel
Publisher: Cengage Learning  Chemistry & Chemical Reactivity
Principles Of Chemical Reactivity: Energy And Chemical Reactions. 58PS Similar questions
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