Question

The valencies or charges on some substances are given below

$$\begin{gathered} \mathrm{Zinc}\mathrm{ion}\left(2^{+}\right)\mathrm{Nitrogen}\left(3^{+}\right)\mathrm{Oxygen}\left(2^{-}\right)\mathrm{Phosphate}\mathrm{ion}\left(3^{-}\right) \\ \mathrm{Sodium}\mathrm{ion}\left(1^{+}\right)\mathrm{Bromide}\mathrm{ion}\left(1^{-}\right)\mathrm{Lead}\mathrm{ion}\left(2^{+}\right) \end{gathered}$$

Using the above information, write down the chemical formulae of the following:

1. Zinc phosphate
2. Nitrogen oxide
3. Sodium phosphate
4. Lead bromide

Answer 1

a. Zinc Phosphate:

1. Chemical symbol of Zinc is $\mathrm{Zn}$ and charge is $2^{+}$.
2. Chemical formula of Phosphate is ${\mathrm{PO}}_4{}^{3-}$ and charge is $3^{-}$.
3. The chemical equation is shown below.
   ${\mathrm{Zn}}^{2+}+{{\mathrm{PO}}_4}^{3-}\to {\mathrm{Zn}}_3{\left({\mathrm{PO}}_4\right)}_2$
4. Hence, chemical formula of Zinc phosphate is ${\mathbf{Zn}}_{\mathbf{3}}{\mathbf{\left(}{\mathbf{PO}}_{\mathbf{4}}\mathbf{\right)}}_{\mathbf{2}}$.

b. Nitrogen oxide:

1. Chemical symbol of Nitrogen is $\mathrm{N}$ and charge is $3^{+}$.
2. Chemical symbol of Oxygen is $\mathrm{O}$ and charge is $2^{-}$.
3. The chemical equation is shown below.
   ${\mathrm{N}}^{3+}+{\mathrm{O}}^{2-}\to {\mathrm{N}}_2{\mathrm{O}}_3$
4. Hence, chemical formula of Nitrogen oxide is ${\mathbf{N}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}$.

c. Sodium phosphate:

1. Chemical symbolof Sodium is $\mathrm{Na}$ and charge is $1^{+}$.
2. Chemical formula of Phosphate is ${{\mathrm{PO}}_4}^{3-}$ and charge is $3^{-}$.
3. The chemical equation is shown below.
   ${\mathrm{Na}}^{+}+{{\mathrm{PO}}_4}^{3-}\to {\mathrm{Na}}_3{\mathrm{PO}}_4$
4. Hence, chemical formula of Sodium phosphate is ${\mathbf{Na}}_{\mathbf{3}}{\mathbf{PO}}_{\mathbf{4}}$.

d. Lead bromide:

1. Chemical formula of Lead is $\mathrm{Pb}$ and charge is $2^{+}$.
2. Chemical formula of Bromide is $\mathrm{Br}$ and charge is $1^{-}$.
3. The chemical equation is shown below.
   ${\mathrm{Pb}}^{+2}+{\mathrm{Br}}^{-}\to {\mathrm{PbBr}}_2$
4. Hence, chemical formula of Lead bromide is ${\mathbf{PbBr}}_{\mathbf{2}}$.