Chapter 3, Problem 101QP

(a)

Interpretation Introduction

Interpretation:

The chemical formula of lead (II) chloride.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. The roman number, (II), indicates that the lead ion $\left({\text{Pb}}^{2+}\right)$ carries a $+2$ charge while each chloride ion $\left({\text{Cl}}^{-}\right)$ carries a $-1$ charge. To neutralize the charges, two chloride ions $\left({\text{2 Cl}}^{-}\right)$ are required for one lead ion $\left({\text{Pb}}^{2+}\right)$ to form an electrically-neutral compound. Therefore, the chemical formula of lead (II) chloride is ${\text{PbCl}}_2$ .

(b)

Interpretation Introduction

Interpretation:

The chemical formula of magnesium phosphate.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. Each magnesium ion carries a $+2$ charge. Thus, to neutralize the charges, three magnesium ions $\left({\text{3 Mg}}^{+}\right)$ are required for two phosphate ions $\left({\text{2 PO}}_4^{3-}\right)$ to form an electrically-neutral compound. Therefore, the chemical formula of magnesium phosphate is ${\text{Mg}}_3{\left({\text{PO}}_4\right)}_2$ .

(c)

Interpretation Introduction

Interpretation:

The chemical formula of nitrogen triiodide.

Explanation of Solution

The symbols of elements are analyzed on the basis of their position in the periodic table. To write the chemical formula of a molecular compound, a prefix is used to indicate the number of each atom in the compound. Therefore, the chemical formula of nitrogen triiodide is ${\text{NI}}_3$ .

(d)

Interpretation Introduction

Interpretation:

The chemical formula of iron (III) oxide.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. The roman number, (III), indicates that iron ion $\left({\text{Fe}}^{3+}\right)$ carries a $+3$ charge while each oxide ion $\left({\text{O}}^{2-}\right)$ carries a $-2$ charge. To neutralize the charges, three oxide ions $\left({\text{3 O}}^{2-}\right)$ are required for two iron ions $\left({\text{2 Fe}}^{3+}\right)$ to form an electrically-neutral compound. Therefore, the chemical formula of lead (III) oxide is ${\text{Fe}}_2{\text{O}}_3$ .

(e)

Interpretation Introduction

Interpretation:

The chemical formula of calcium nitride.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. Each calcium ion carries a $+2$ charge while each nitride ion $\left({\text{N}}^{3-}\right)$ carries a $-3$ charge. In order to neutralize the charges, two nitride ions $\left({\text{2 N}}^{3-}\right)$ are required for two calcium ions $\left({\text{2 Ca}}^{2+}\right)$ . Therefore, the chemical formula of calcium nitride is ${\text{Ca}}_3{\text{N}}_2$ .

(f)

Interpretation Introduction

Interpretation:

The chemical formula of barium hydroxide.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. The bromide ion $\left({\text{Ba}}^{2+}\right)$ carries a $+2$ charge. In order to neutralize the charges, two hydroxide ions are required $\left({\text{2 OH}}^{-}\right)$ for one barium ion $\left({\text{Ba}}^{2+}\right)$ . Therefore, the chemical formula of barium hydroxide is $\text{Ba}{\left(\text{OH}\right)}_2$ .

(g)

Interpretation Introduction

Interpretation:

The chemical formula of dichlorine pentaoxide.

Explanation of Solution

The symbols of elements are analyzed on the basis of their position in the periodic table. To write the chemical formula of a molecular compound, a prefix is used to indicate the number of each atom in the compound. Therefore, the chemical formula of dichlorine pentaoxide is ${\text{Cl}}_2{\text{O}}_5$ .

(h)

Interpretation Introduction

Interpretation:

The chemical formula of ammonium chloride.

Explanation of Solution

The charges and symbols of elements are analyzed on the basis of their position in the periodic table. Each chloride ion $\left({\text{Cl}}^{-}\right)$ carries a $-2$ charge. In order to neutralize the charges, one chloride ion $\left({\text{ Cl}}^{-}\right)$ is required for one ammonium ion $\left({\text{NH}}_4^{+}\right)$ . Therefore, the chemical formula of ammonium chloride is ${\text{NH}}_4\text{Cl}$ .