Chapter 19, Problem 9STP

Interpretation Introduction

Interpretation:

Oxidation number of each element in the given reaction is to be identified.

Concept introduction:

Oxidation number: It is defined as charge the atom would have if electrons are not shared but transfer completely.

There are some rules to assign oxidation number:

• For an atom in its elemental form, oxidation number=0
• For a monatomic ion, oxidation number=charge of ion
• The sum of oxidation number value for the atoms in a molecule equal to zero for neutral compound and equal to total charge if it is a polyatomic ion
• For group (I)A, oxidation number=+1 in all compounds
• For group (II)A, oxidation number=+2 in all compounds
• For halogens, oxidation number=-1 in all compounds

Answer to Problem 9STP

Oxidation state of each participant is mentioned:

${\stackrel{0}{I}}_2+\stackrel{+4}{Pb}{\stackrel{-2}{O}}_2\to \stackrel{+5}{I}{\stackrel{-2}{O}}_3{}^{-}+\stackrel{+2}{P{b}^{+2}}$

Explanation of Solution

• Oxidation number of $I_2$ is zero because for an atom in its elemental form, oxidation number=0
• Oxidation number of $O$ is -2 in oxide form.
• Oxidation state of $PbinPb{O}_2$ is calculated as :

$\begin{array}{l}x+(-2\times 2)=0\\ x-4=0\\ x=4\end{array}$

• Oxidation number of $IinI{O}_3{}^{-}$is calculated as :

$\begin{array}{l}x+(-2\times 3)=-1\\ x-6=-1\\ x=6-1\\ x=5\end{array}$

• Oxidation number of $P{b}^{+2}$ is +2 because for an ion, oxidation number=charge of ion

Conclusion

Oxidation state of each participant is mentioned:

${\stackrel{0}{I}}_2+\stackrel{+4}{Pb}{\stackrel{-2}{O}}_2\to \stackrel{+5}{I}{\stackrel{-2}{O}}_3{}^{-}+\stackrel{+2}{P{b}^{+2}}$