Chapter 2.8, Problem 2.10BFP

(a)

Interpretation Introduction

Interpretation:

The correct formula for $\text{copper}\left(\text{II}\right)\text{ nitride}$ is to be determined.

Concept introduction:

The general rules for writing the systematic names of ionic compounds are as follows:

1) In binary ionic compounds, the name of the metal is written as the original name whereas the name of the non-metal has the root word with the suffix $\text{-}ide$.

2) In metals that form more than one ion, the Latin root of the metal is followed by a suffix $\text{-}ous$ for the ion with lower charge and suffix $\text{-}ic$ for the ion with a higher charge. In the systematic name, the name of the metal is followed by the charge on the metal within the parentheses in roman numerals.

3) In the family of two oxoanions, the ion with more oxygen atoms has the non-metal root and a suffix $\text{-}ate$ added to it. The ion with fewer oxygen atoms has the non-metal root and the suffix $\text{-}ite$ added to it.

4) For hydrated ionic compounds, the total number of water molecules are represented by the Greek numerical prefixes followed by the word hydrate.

Answer to Problem 2.10BFP

The correct formula for the compound $\text{copper}\left(\text{II}\right)\text{ nitride}$ is ${\text{Cu}}_3{\text{N}}_2$.

Explanation of Solution

Copper is a transition element. Therefore, it forms more than one ion. The Roman numeral $\text{II}$ within the parentheses in the systematic name indicates that copper has a charge of $+2$ on it. The nitride ion is represented by the formula ${\text{N}}^{3-}$. In order to balance the $+2$ charge on the copper ion, two nitride ions associate with three copper ions as follows:

${\text{3Cu}}^{2+}+2{\text{N}}^{3-}\to {\text{Cu}}_3{\text{N}}_2$

Conclusion

The correct formula for the compound $\text{copper}\left(\text{II}\right)\text{ nitride}$ is ${\text{Cu}}_3{\text{N}}_2$.

(b)

Interpretation Introduction

Interpretation:

The correct name for the compound ${\text{PbI}}_2$ is to be determined.

Concept introduction:

The general rules for writing the systematic names of ionic compounds are as follows:

1) In binary ionic compounds, the name of the metal is written as the original name whereas the name of the non-metal has the root word with the suffix $\text{-}ide$.

2) In metals that form more than one ion, the Latin root of the metal is followed by a suffix $\text{-}ous$ for the ion with lower charge and suffix $\text{-}ic$ for the ion with a higher charge. In the systematic name, the name of the metal is followed by the charge on the metal within the parentheses in roman numerals.

3) In the family of two oxoanions, the ion with more oxygen atoms has the non-metal root and a suffix $\text{-}ate$ added to it. The ion with fewer oxygen atoms has the non-metal root and the suffix $\text{-}ite$ added to it.

4) For hydrated ionic compounds, the total number of water molecules are represented by the Greek numerical prefixes followed by the word hydrate.

Answer to Problem 2.10BFP

The correct name for the compound ${\text{PbI}}_2$ is $\text{lead}\left(\text{II}\right)\text{ iodide}$.

Explanation of Solution

The element lead forms more than one ion $\left({\text{Pb}}^{4+}{\text{and Pb}}^{2+}\right)$. The element iodine belongs to the $7\text{A}\left(17\right)$ group in the periodic table and therefore gains an electron to form iodide ion ${\text{I}}^{-}$. To balance the total charge of $-2$ on the iodide ion, the lead ion must have a charge of $+2$. The charge on the lead ion is written in Roman numerals within the parentheses next to the metal name in the systematic name. Therefore the correct name for the compound ${\text{PbI}}_2$ is $\text{lead}\left(\text{II}\right)\text{ iodide}$.

Conclusion

The correct name for the compound ${\text{PbI}}_2$ is $\text{lead}\left(\text{II}\right)\text{ iodide}$.

(c)

Interpretation Introduction

Interpretation:

The correct formula for the compound chromic sulfide is to be determined.

Concept introduction:

The general rules for writing the systematic names of ionic compounds are as follows:

1) In binary ionic compounds, the name of the metal is written as the original name whereas the name of the non-metal has the root word with the suffix $\text{-}ide$.

2) In metals that form more than one ion, the Latin root of the metal is followed by a suffix $\text{-}ous$ for the ion with lower charge and suffix $\text{-}ic$ for the ion with a higher charge. In the systematic name, the name of the metal is followed by the charge on the metal within the parentheses in roman numerals.

3) In the family of two oxoanions, the ion with more oxygen atoms has the non-metal root and a suffix $\text{-}ate$ added to it. The ion with fewer oxygen atoms has the non-metal root and the suffix $\text{-}ite$ added to it.

4) For hydrated ionic compounds, the total number of water molecules are represented by the Greek numerical prefixes followed by the word hydrate.

Answer to Problem 2.10BFP

The correct formula for the compound chromic sulfide is ${\text{Cr}}_2{\text{S}}_3$.

Explanation of Solution

The chromic ion is represented by the formula ${\text{Cr}}^{3+}$. The element sulfur belongs to the $6\text{A}\left(16\right)$ group in the periodic table. Therefore the element sulfur gains two electrons to form the sulfide ion as follows;

$\text{S}+2{\text{e}}^{-}\to {\text{S}}^{2-}$

The chromic and sulfide ions combine in the $2:3$ ratio to form the compound chromic sulfide as follows:

$2{\text{Cr}}^{3+}+3{\text{S}}^{2-}\to {\text{Cr}}_2{\text{S}}_3$

Conclusion

The correct formula for the compound chromic sulfide is ${\text{Cr}}_2{\text{S}}_3$.

(d)

Interpretation Introduction

Interpretation:

The systematic name for $\text{FeO}$ is to be determined.

Concept introduction:

The general rules for writing the systematic names of ionic compounds are as follows:

1) In binary ionic compounds, the name of the metal is written as the original name whereas the name of the non-metal has the root word with the suffix $\text{-}ide$.

2) In metals that form more than one ion, the Latin root of the metal is followed by a suffix $\text{-}ous$ for the ion with lower charge and suffix $\text{-}ic$ for the ion with a higher charge. In the systematic name, the name of the metal is followed by the charge on the metal within the parentheses in roman numerals.

3) In the family of two oxoanions, the ion with more oxygen atoms has the non-metal root and a suffix $\text{-}ate$ added to it. The ion with fewer oxygen atoms ahs the non-metal root and the suffix $\text{-}ite$ added to it.

4) For hydrated ionic compounds, the total number of water molecules are represented by the Greek numerical prefixes followed by the word hydrate.

Answer to Problem 2.10BFP

The systematic name for $\text{FeO}$ is $\text{iron}\left(\text{II}\right)\text{ oxide}$.

Explanation of Solution

The element oxygen is a non-metal from the $6\text{A}\left(16\right)$ group in the periodic table. Therefore it gains two electrons to form the oxide ion as follows:

$\text{O}+2{\text{e}}^{-}\to {\text{O}}^{2-}$

The element iron forms more than one ion $\left({\text{Fe}}^{2+}{\text{and Fe}}^{3+}\right)$. In order to balance the charge on the oxide ion, the ion that combines with it is the ferrous ion $\left({\text{Fe}}^{2+}\right)$.

${\text{Fe}}^{2+}+{\text{O}}^{2-}\to \text{FeO}$

Therefore, the charge on the ferrous ion is mentioned as Roman numerals within the parentheses next to the metal name in the systematic name.

Conclusion

The systematic name for $\text{FeO}$ is $\text{iron}\left(\text{II}\right)\text{ oxide}$.