Chapter 2, Problem 2.96QP

(a)

Interpretation Introduction

To determine: The chemical formula ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$, of manganese $\left(\text{II}\right)$ phosphate is incorrect or not.

Interpretation: The chemical formula ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$, of manganese $\left(\text{II}\right)$ phosphate is incorrect or not is to be predicted.

Concept introduction: The naming of the compound is done on the basis of atoms attached to it and the charge present on each atom.

Answer to Problem 2.96QP

The chemical formula ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$, of manganese $\left(\text{II}\right)$ phosphate is incorrect.

Explanation of Solution

The oxidation state of manganese in manganese $\left(\text{II}\right)$ phosphate is $+2$.

The oxidation state of phosphate ion atom is $-3$.

The oxidation state of manganese is assumed to be $x$.

The oxidation state of the metal center present in ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$ is expressed as,

$\begin{array}{c}3x+3\left(-3\right)=0\\ x=\frac{9}{3}\\ =+3\end{array}$

The calculated oxidation state of manganese is $+3$.

The given oxidation state and the calculated oxidation state is not same therefore, the chemical formula ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$, of manganese $\left(\text{II}\right)$ phosphate is incorrect.

(b)

Interpretation Introduction

To determine: The chemical formula ${\text{NiBr}}_2$, of nickel $\left(\text{II}\right)$ bromide is incorrect or not.

Interpretation: The chemical formula ${\text{NiBr}}_2$, of nickel $\left(\text{II}\right)$ bromide is incorrect or not is to be predicted.

Concept introduction: The naming of the compound is done on the basis of atoms attached to it and the charge present on each atom.

Answer to Problem 2.96QP

The chemical formula ${\text{NiBr}}_2$, of nickel $\left(\text{II}\right)$ bromide is correct.

Explanation of Solution

The oxidation state of nickel in nickel $\left(\text{II}\right)$ bromide is $+2$.

The oxidation state of bromine atom is $-1$.

The oxidation state of nickel is assumed to be $x$.

The oxidation state of the metal center present in ${\text{NiBr}}_2$ is expressed as,

$\begin{array}{c}x+2\left(-1\right)=0\\ x=+2\end{array}$

The calculated oxidation state of nickel is $+2$.

The given oxidation state and the calculated oxidation state is same therefore, the chemical formula ${\text{NiBr}}_2$, of titanium $\left(\text{IV}\right)$ bromide is correct.

(c)

Interpretation Introduction

To determine: The chemical formula ${\text{Cr}}_2{\text{S}}_3$, of chromium $\left(\text{III}\right)$ sulfide is incorrect or not.

Interpretation: The chemical formula ${\text{Cr}}_2{\text{S}}_3$, of chromium $\left(\text{III}\right)$ sulfide is incorrect or not is to be predicted.

Concept introduction: The naming of the compound is done on the basis of atoms attached to it and the charge present on each atom.

Answer to Problem 2.96QP

The chemical formula ${\text{Cr}}_2{\text{S}}_3$, of chromium $\left(\text{III}\right)$ sulfide is correct.

Explanation of Solution

The oxidation state of chromium in chromium $\left(\text{III}\right)$ sulfide is $+3$.

The oxidation state of sulfide ion is $-2$.

The oxidation state of chromium is assumed to be $x$.

The oxidation state of the metal center present in ${\text{Cr}}_2{\text{S}}_3$ is expressed as,

$\begin{array}{c}2x+3\left(-2\right)=0\\ x=\frac{6}{2}\\ =+3\end{array}$

The calculated oxidation state of chromium is $+3$.

The given oxidation state and the calculated oxidation state is same therefore, the chemical formula ${\text{Cr}}_2{\text{S}}_3$, of chromium $\left(\text{III}\right)$ sulfide is correct.

(d)

Interpretation Introduction

To determine: The chemical formula ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$, of copper $\left(\text{II}\right)$ sulfate hexahydrate is incorrect or not.

Interpretation: The chemical formula ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$, of copper $\left(\text{II}\right)$ sulfate hexahydrate is incorrect or not is to be predicted.

Concept introduction: The naming of the compound is done on the basis of atoms attached to it and the charge present on each atom.

Answer to Problem 2.96QP

The chemical formula ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$, of copper $\left(\text{II}\right)$ sulfate hexahydrate is correct.

Explanation of Solution

The oxidation state of copper in copper $\left(\text{II}\right)$ sulfate hexahydrate is $+2$.

The oxidation state of sulfate ion is $-2$.

The oxidation state of copper is assumed to be $x$.

The oxidation state of the metal center present in ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$ is expressed as,

$\begin{array}{c}x+\left(-2\right)=0\\ x=+2\end{array}$

The calculated oxidation state of copper is $+2$.

The given oxidation state and calculated oxidation state is not same therefore, the chemical formula ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$ of copper $\left(\text{II}\right)$ sulfate hexahydrate is correct.

Conclusion

1. a. The chemical formula ${\text{Mn}}_3{\left({\text{PO}}_4\right)}_3$, of manganese $\left(\text{II}\right)$ phosphate is incorrect.
2. b. The chemical formula ${\text{NiBr}}_2$, of nickel $\left(\text{II}\right)$ bromide is correct.
3. c. The chemical formula ${\text{Cr}}_2{\text{S}}_3$, of chromium $\left(\text{III}\right)$ sulfide is correct.
4. d. The chemical formula ${\text{CuSO}}_4\cdot 6{\text{H}}_2\text{O}$, of copper $\left(\text{II}\right)$ sulfate hexahydrate is correct.