Question

What do you mean by molecular formula? Write the molecular formula of the following compounds:

Calcium nitrate, Zinc sulphate, Ammonium carbonate, Aluminium oxide, Ammonium hydroxide

Answer 1

• The symbolic representation of the molecule of a compound is known as its molecular formula.
• The molecular formula of the given compounds can be determined by knowing the symbols and the valencies of the elements or the radicals participating.

Calcium nitrate $$\begin{gathered} \mathrm{Ca}{\mathrm{NO}}_3^{} \\ +2-1 \end{gathered}$$ On interchanging the valencies the molecular formula of the compound comes out to be $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$	Zinc sulphate $$\begin{gathered} \mathrm{Zn}{\mathrm{SO}}_4^{} \\ +2-2 \end{gathered}$$ On interchanging the valencies the molecular formula of the compound comes out to be $\mathrm{ZnS}{\mathrm{O}}_4$	Ammonium carbonate $$\begin{gathered} {\mathrm{NH}}_4{\mathrm{CO}}_3^{} \\ +1-2 \end{gathered}$$ On interchanging the valencies the molecular formula of the compound comes out to be ${\left({\mathrm{NH}}_4\right)}_2{\mathrm{CO}}_3$
Aluminium oxide $$\begin{gathered} \mathrm{Al}\mathrm{O} \\ +3-2 \end{gathered}$$ On interchanging the valencies the molecular formula of the compound comes out to be ${\mathrm{Al}}_2{\mathrm{O}}_3$	Ammonium hydroxide $$\begin{gathered} {\mathrm{NH}}_4\mathrm{OH} \\ +1-1 \end{gathered}$$ On interchanging the valencies the molecular formula of the compound comes out to be ${\mathrm{Al}}_2{\mathrm{O}}_3$