Chapter 12, Problem 81E

Interpretation Introduction

(a)

Interpretation:

The formula unit formed by the combination of cation ${\text{Sr}}^{\text{2+}}$ and anion ${\text{As}}^{3-}$ is to be written.

Concept introduction:

Formula unit is the empirical formula of the ionic and covalent compound which is used in stoichiometric calculations. Formula unit for the ionic compound is the ratio of the lowest whole number. In ionic compounds, the charge of the cation is written as a subscript of the anion. On the other hand, the charge on anion is written as a subscript on the cation.

Answer to Problem 81E

The formula unit formed by the combination of cation ${\text{Sr}}^{\text{2+}}$ and anion ${\text{As}}^{3-}$ is ${\text{Sr}}_{\text{3}}{\text{As}}_{\text{2}}$.

Explanation of Solution

The cation ${\text{Sr}}^{\text{2+}}$ carries two positive charges which should be written as a subscript of the anion ${\text{As}}^{3-}$. On the other hand, the anion ${\text{As}}^{3-}$ caries three negative charges that means three should be written as a subscript of the cation ${\text{Sr}}^{\text{2+}}$. So, the formula unit for cation ${\text{Sr}}^{\text{2+}}$ and anion ${\text{As}}^{3-}$ is ${\text{Sr}}_{\text{3}}{\text{As}}_{\text{2}}$.

Conclusion

The formula unit for cation ${\text{Sr}}^{\text{2+}}$ and anion ${\text{As}}^{3-}$ is ${\text{Sr}}_{\text{3}}{\text{As}}_{\text{2}}$.

Interpretation Introduction

(b)

Interpretation:

The formula unit formed by the combination of cation ${\text{Ra}}^{2+}$ and anion ${\text{O}}^{2-}$ is to be written.

Concept introduction:

Formula unit is the empirical formula of the ionic and covalent compound which is used in stoichiometric calculations. Formula unit for the ionic compound is the ratio of the lowest whole number. In ionic compounds, the charge of the cation is written as a subscript of the anion. On the other hand, the charge on anion is written as a subscript on the cation.

Answer to Problem 81E

The formula unit by the combination cation ${\text{Ra}}^{2+}$ and anion ${\text{O}}^{2-}$ is $\text{RaO}$.

Explanation of Solution

The cation ${\text{Ra}}^{2+}$ is carries two positive charges which should be written as a subscript of the anion ${\text{O}}^{2-}$. On the other hand, the anion ${\text{O}}^{2-}$ is carries two negative charges that means two should be written as a subscript of the cation ${\text{Ra}}^{2+}$. So, the formula unit for cation ${\text{Ra}}^{2+}$ and anion ${\text{O}}^{2-}$ is $\text{RaO}$.

Conclusion

The formula unit for cation ${\text{Ra}}^{2+}$ and anion ${\text{O}}^{2-}$ is $\text{RaO}$.

Interpretation Introduction

(c)

Interpretation:

The formula unit formed by the combination of cation ${\text{Al}}^{3+}$ and anion ${\text{CO}}_3{}^{2-}$ is to be written.

Concept introduction:

Formula unit is the empirical formula of the ionic and covalent compound which is used in stoichiometric calculations. Formula unit for the ionic compound is the ratio of the lowest whole number. In ionic compounds, the charge of the cation is written as a subscript of the anion. On the other hand, the charge on anion is written as a subscript on the cation.

Answer to Problem 81E

The formula unit formed by the combination of cation ${\text{Al}}^{3+}$ and anion ${\text{CO}}_3{}^{2-}$ is ${\text{Al}}_2{\left({\text{CO}}_3\right)}_3$.

Explanation of Solution

The cation ${\text{Al}}^{3+}$ is carries three positive charges which should be written as a subscript of the anion ${\text{CO}}_3{}^{2-}$. On the other hand, the anion ${\text{CO}}_3{}^{2-}$ is carries two negative charges that means two should be written as a subscript of the cation ${\text{Al}}^{3+}$. So, the formula unit for cation ${\text{Al}}^{3+}$ and anion ${\text{CO}}_3{}^{2-}$ is ${\text{Al}}_2{\left({\text{CO}}_3\right)}_3$.

Conclusion

The formula unit for cation ${\text{Al}}^{3+}$ and anion ${\text{CO}}_3{}^{2-}$ is ${\text{Al}}_2{\left({\text{CO}}_3\right)}_3$.

Interpretation Introduction

(d)

Interpretation:

The formula unit formed by the combination of cation ${\text{Cd}}^{2+}$ and anion ${\text{OH}}^{-}$ is to be written.

Concept introduction:

Formula unit is the empirical formula of the ionic and covalent compound which is used in stoichiometric calculations. Formula unit for the ionic compound is the ratio of the lowest whole number. In ionic compounds, the charge of the cation is written as a subscript of the anion. On the other hand, the charge on anion is written as a subscript on the cation.

Answer to Problem 81E

The formula unit formed by the combination of cation ${\text{Cd}}^{2+}$ and anion ${\text{OH}}^{-}$ is $\text{Cd}{\left(\text{OH}\right)}_2$

Explanation of Solution

The cation ${\text{Cd}}^{2+}$ is carries two positive charges which should be written as a subscript of the anion ${\text{OH}}^{-}$. On the other hand, the anion ${\text{OH}}^{-}$ is carries one negative charge that means one should be written as a subscript of the cation ${\text{Cd}}^{2+}$. So, the formula unit for cation ${\text{Cd}}^{2+}$ and anion ${\text{OH}}^{-}$ is $\text{Cd}{\left(\text{OH}\right)}_2$.

Conclusion

The formula unit for cation ${\text{Cd}}^{2+}$ and anion ${\text{OH}}^{-}$ is $\text{Cd}{\left(\text{OH}\right)}_2$.