Chapter 19, Problem 47A

Interpretation Introduction

(a)

Interpretation:

The given reaction is to be identified that whether the reaction is redox or not.

Concept introduction:

A reaction is called redox reaction if it involves both oxidation and reduction.

Oxidation is loss of electrons and reduction is gain of electrons.

Therefore both gain and loss should occur during the reaction.

Answer to Problem 47A

The given reaction involves no change in oxidation number of atoms. Thus this is not a redox reaction.

Explanation of Solution

$LiOH+HN{O}_3\to LiN{O}_3+H_{2}O$

Oxidation numbers of various atoms are:

$\stackrel{+1}{Li}\stackrel{-2}{O}\stackrel{+1}{H}+\stackrel{+1}{H}\stackrel{+5}{N}{\stackrel{-2}{O}}_3\to \stackrel{+1}{Li}\stackrel{+5}{N}{\stackrel{-2}{O}}_3+{\stackrel{+1}{H}}_2\stackrel{-2}{O}$

The given reaction involves no change in oxidation number of atoms. Thus this is not a redox reaction.

Interpretation Introduction

(b)

Interpretation:

The given reaction is to be identified that whether the reaction is redox or not.

Concept introduction:

A reaction is called redox reaction if it involves both oxidation and reduction.

Oxidation is loss of electrons and reduction is gain of electrons.

Therefore both gain and loss should occur during the reaction.

Answer to Problem 47A

The given reaction involves change in oxidation number of atoms. Thus this is a redox reaction.

Explanation of Solution

$Mg{I}_2+B{r}_2\to MgB{r}_2+I_2$

Oxidation numbers of various atoms are:

$\stackrel{+2}{Mg}{\stackrel{-1}{I}}_2+\stackrel{0}{B{r}_2}\to \stackrel{+2}{Mg}{\stackrel{-1}{Br}}_2+\stackrel{0}{I_2}$

The given reaction involves change in oxidation number of atoms. Oxidation number of iodine is increasing and bromine is decreasing. Thus this is a redox reaction.