Chapter 9, Problem 9.25EP

(a)

Interpretation Introduction

Interpretation:

The reaction ${\text{SO}}_{\text{2}}\stackrel{}{\to }{\text{SO}}_{\text{3}}$ undergoes oxidation or reduction has to be determined.

Concept Introduction:

Oxidation:

Loss of electrons from an atom ion or molecule during a chemical reaction is known as oxidation.  Oxidation state of atom ion or molecule will increase in this process.  In simple it is the addition of oxygen.  Reduction is gaining of electrons.

Example    

Here ${\text{Fe}}^{\text{2+}}$ oxidized to ${\text{Fe}}^{\text{3+}}$ by the removal of a single electron.

Oxidation number:

It is the charge of an atom, provided if the compound is composed of ions.  On oxidation the oxidation number will increase and on reduction the oxidation number will decrease.  It can be also called as degree of oxidation.

Example:

`    $\text{CuO+Mg}\to \text{Cu+MgO}$

    Oxidation number of $\text{Cu}$ in $\text{CuO}$  = +2

    Oxidation number of $\text{Mg}$ = 0

    Oxidation number of $\text{Cu}$ = 0

    Oxidation number of $\text{Mg}$ in $\text{MgO}$  = +2

Here we can see that the oxidation number of copper is decreased and the oxidation number of magnesium is increased.

(b)

Interpretation Introduction

Interpretation:

The reaction ${\text{N}}_{\text{2}}\text{O}\stackrel{}{\to }\text{NO}$ undergoes oxidation or reduction has to be determined.

Concept Introduction:

Oxidation:

Loss of electrons from an atom ion or molecule during a chemical reaction is known as oxidation.  Oxidation state of atom ion or molecule will increase in this process.  In simple it is the addition of oxygen.  Reduction is gaining of electrons.

Example    

Here ${\text{Fe}}^{\text{2+}}$ oxidized to ${\text{Fe}}^{\text{3+}}$ by the removal of a single electron.

Oxidation number:

It is the charge of an atom, provided if the compound is composed of ions.  On oxidation the oxidation number will increase and on reduction the oxidation number will decrease.  It can be also called as degree of oxidation.

Example:

`    $\text{CuO+Mg}\to \text{Cu+MgO}$

    Oxidation number of $\text{Cu}$ in $\text{CuO}$  = +2

    Oxidation number of $\text{Mg}$ = 0

    Oxidation number of $\text{Cu}$ = 0

    Oxidation number of $\text{Mg}$ in $\text{MgO}$  = +2

Here we can see that the oxidation number of copper is decreased and the oxidation number of magnesium is increased.

(c)

Interpretation Introduction

Interpretation:

The reaction ${\text{Cr}}^{\text{3+}}\stackrel{}{\to }{\text{Cr}}^{\text{2+}}$ undergoes oxidation or reduction has to be determined.

Concept Introduction:

Reduction:

It is the gaining of electrons.  Oxidation number will decrease in this.  Reduction can be also termed as addition of Hydrogen or removal of Oxygen.

Example:

  ${\text{Zn}}^{\text{2+}}{\text{+2e}}^{\text{-}}\underset{}{\to }\text{Zn}$

The oxidation No of Zn is reduced.

(d)

Interpretation Introduction

Interpretation:

The reaction ${\text{S}}^{\text{2-}}\stackrel{}{\to }\text{S}$ undergoes oxidation or reduction has to be determined.

Concept Introduction:

Oxidation:

Loss of electrons from an atom ion or molecule during a chemical reaction is known as oxidation.  Oxidation state of atom ion or molecule will increase in this process.  In simple it is the addition of oxygen.  Reduction is gaining of electrons.

Example    

Here ${\text{Fe}}^{\text{2+}}$ oxidized to ${\text{Fe}}^{\text{3+}}$ by the removal of a single electron.

Oxidation number:

It is the charge of an atom, provided if the compound is composed of ions.  On oxidation the oxidation number will increase and on reduction the oxidation number will decrease.  It can be also called as degree of oxidation.

Example:

`    $\text{CuO+Mg}\to \text{Cu+MgO}$

    Oxidation number of $\text{Cu}$ in $\text{CuO}$  = +2

    Oxidation number of $\text{Mg}$ = 0

    Oxidation number of $\text{Cu}$ = 0

    Oxidation number of $\text{Mg}$ in $\text{MgO}$  = +2

Here we can see that the oxidation number of copper is decreased and the oxidation number of magnesium is increased.