Chapter 18, Problem 12A

(a)

Interpretation Introduction

Interpretation: The oxidation state of all atoms in ${\text{CuCl}}_{\text{2}}$ needs to be determined.

Concept Introduction: Oxidation state indicates the number assigned to an element in a compound, which indicates the number of electrons transfer by the atom of that element.

It can be calculated with the help of standard oxidation states of certain elements like halogens with -1 oxidation state, alkali metals with +1 and alkaline earth metals with +2 oxidation state whereas O shows -2 oxidation state.

Answer to Problem 12A

• Cu = +2
• Cl = -1

Explanation of Solution

Let’s assume oxidation state of Cu = x

Cl = -1

  $\begin{array}{l}{\text{CuCl}}_{\text{2}}\\ x+(2\times -1)=0\\ x-2=0\\ x=+2\end{array}$

(b)

Interpretation Introduction

Interpretation: The oxidation state of all atoms in ${\text{CrCl}}_{\text{3}}$ needs to be determined.

Concept Introduction: Oxidation state indicates the number assigned to an element in a compound, which indicates the number of electrons transfer by the atom of that element.

It can be calculated with the help of standard oxidation states of certain elements like halogens with -1 oxidation state, alkali metals with +1 and alkaline earth metals with +2 oxidation state whereas O shows -2 oxidation state.

Answer to Problem 12A

• Cr = +3
• Cl = -1

Explanation of Solution

Let’s assume oxidation state of Cr = x

Cl = -1

  $\begin{array}{l}{\text{CrCl}}_{\text{3}}\\ x+(3\times -1)=0\\ x-3=0\\ x=+3\end{array}$

(c)

Interpretation Introduction

Interpretation: The oxidation state of all atoms in ${\text{HCrO}}_{{}_{\text{4}}}^{-}$ needs to be determined.

Concept Introduction: Oxidation state indicates the number assigned to an element in a compound, which indicates the number of electrons transfer by the atom of that element.

It can be calculated with the help of standard oxidation states of certain elements like halogens with -1 oxidation state, alkali metals with +1 and alkaline earth metals with +2 oxidation state whereas O shows -2 oxidation state.

Answer to Problem 12A

• Cr = +2
• H= +1
• O = -2

Explanation of Solution

Let’s assume oxidation state of Cr = x

O = -2

H = +1

  $\begin{array}{l}{\text{HCrO}}_{{}_{\text{4}}}^{-}\\ (1\times +1)+x+(4\times -1)=-1\\ 1+x-4=-1\\ x=+2\end{array}$

(d)

Interpretation Introduction

Interpretation: The oxidation state of all atoms in ${\text{Cr}}_{\text{2}}{\text{O}}_{\text{3}}$ needs to be determined.

Concept Introduction: Oxidation state indicates the number assigned to an element in a compound, which indicates the number of electrons transfer by the atom of that element.

It can be calculated with the help of standard oxidation states of certain elements like halogens with -1 oxidation state, alkali metals with +1 and alkaline earth metals with +2 oxidation state whereas O shows -2 oxidation state.

Answer to Problem 12A

• Cr = +3
• O = -2

Explanation of Solution

Let’s assume oxidation state of Cr = x

O = -2

  $\begin{array}{l}{\text{Cr}}_{\text{2}}{\text{O}}_{\text{3}}\\ 2x+(3\times -2)=0\\ 2x-6=0\\ 2x=+6\\ x=+3\end{array}$