Question

Write the chemical formula for magnesium phosphate.

Answer 1

The symbol of magnesium is ‘$\mathrm{Mg}$’, having a valency of 2⁺.

The formula of phosphate is ‘${\mathrm{PO}}_4$’ with valency 3^-.

Step 1 –

Write the formula of sodium zincate:

Symbol Valency

Magnesium $\mathrm{Mg}$ 2⁺

Phosphate ${\mathrm{PO}}_4$ 3^-

Step 2 –

Write each symbol with its valency:

${\mathrm{Mg}}^{2+}$ ${{\mathrm{PO}}_4}^{3+}$

Step 3 –

Interchanging the valencies:

$$\begin{gathered} \mathrm{Mg}{\mathrm{PO}}_4 \\ \searrow \swarrow \\ {2}^{+}{3}^{-} \end{gathered}$$

The formula of the compound ferrous sulphide would be ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$ .