Calculate the molecular mass of:

Ammonium nitrate ${\mathrm{NH}}_4{\mathrm{NO}}_3$.

Molecular mass:

• Molecular mass of a substance is the number of times a molecule of the substance is heavier than $\frac{1}{12}th$ of mass of a carbon ($\mathrm{C}-12$) atom.
• Molecular mass of a substance can be obtained by adding the atomic masses of all the atoms present in a molecule of the substance.

The molecular mass of Ammonium nitrate ${\mathrm{NH}}_4{\mathrm{NO}}_3$:

$$\begin{gathered} =\text{Atomic mass of nitrogen+ 4× (atomic mass of hydrogen) +atomic mass of nitrogen + 3×(atomic mass of oxygen)} \\ =14+4\times 1+14+3\times 16 \\ =14+4+14+48 \\ =80\mathrm{a}.\mathrm{m}.\mathrm{u}. \end{gathered}$$

Therefore, molecular mass of ammonium nitrate ${\mathrm{NH}}_4{\mathrm{NO}}_3$ is $80\text{a.m.u.}$