Chapter 5.7, Problem 25P

(a)

Interpretation Introduction

Interpretation:

The value of ${\text{ΔH}}^{\text{0}}$ for the addition of $\text{HCl}$ to ethene should be determined using bond dissociation enthalpy.

Concept introduction:

The amount of heat consumed or given off during the course of a reaction is known as enthalpy of reaction.  Heat is given off when bonds are formed and heat is consumed when bonds are broken.

${\text{ΔH}}^{\text{0}}\text{=}\text{Heat}\text{required}\text{to}\text{break}\text{bonds}\text{-}\text{Heat}\text{released}\text{from}\text{forming}\text{bonds}$

Heat is one form of energy.

The amount of energy required to break a chemical bond is referred to as bond dissociation enthalpy.

(b)

Interpretation Introduction

Interpretation:

The value of ${\text{ΔH}}^{\text{0}}$ for the addition of ${\text{H}}_{\text{2}}$ to ethene should be determined using bond dissociation enthalpy.

Concept introduction:

The amount of heat consumed or given off during the course of a reaction is known as enthalpy of reaction.  Heat is given off when bonds are formed and heat is consumed when bonds are broken.

${\text{ΔH}}^{\text{0}}\text{=}\text{Heat}\text{required}\text{to}\text{break}\text{bonds}\text{-}\text{Heat}\text{released}\text{from}\text{forming}\text{bonds}$

Heat is one form of energy.

The amount of energy required to break a chemical bond is referred to as bond dissociation enthalpy.

(c)

Interpretation Introduction

Interpretation:

It should be identified that whether the given reactions (addition of HCl to ethene and addition of dihydrogen to ethene) are exothermic or endothermic in nature.

Concept introduction:

The amount of heat consumed or given off during the course of a reaction is known as enthalpy of reaction.  Heat is given off when bonds are formed and heat is consumed when bonds are broken.

${\text{ΔH}}^{\text{0}}\text{=}\text{Heat}\text{required}\text{to}\text{break}\text{bonds}\text{-}\text{Heat}\text{released}\text{from}\text{forming}\text{bonds}$

Heat is one form of energy.

The amount of energy required to break a chemical bond is referred to as bond dissociation enthalpy.

A reaction with a negative ${\text{ΔH}}^{\text{0}}$ is called an exothermic reaction.

A reaction with a positive ${\text{ΔH}}^{\text{0}}$ is called an endothermic reaction.

(d)

Interpretation Introduction

Interpretation: It should be identified that whether the given reactions (addition of HCl to ethene and addition of dihydrogen to ethene) are exergonic or endergonic in nature.

Concept introduction:

The amount of heat consumed or given off during the course of a reaction is known as enthalpy of reaction (H).  Heat is given off when bonds are formed and heat is consumed when bonds are broken.

${\text{ΔH}}^{\text{0}}\text{=}\text{Heat}\text{required}\text{to}\text{break}\text{bonds}\text{-}\text{Heat}\text{released}\text{from}\text{forming}\text{bonds}$

Heat is one form of energy.

The amount of energy required to break a chemical bond is referred to as bond dissociation enthalpy.

The mathematical relationship between enthalpy (H) and free energy (G) is,

${\text{ΔG}}^{\text{0}}\text{=}{\text{ΔH}}^{\text{0}}\text{-}\text{TΔS}$

In an exergonic reaction the products have a lower free energy than it consumes.

In an endergonic reaction the product have a higher free energy than it consumes.