Question

What is the atomic mass of aluminum nitrate?

Answer 1

The molecular mass of the given compound. Molecular mass is calculated as the sum of the atomic weights of each individual element constituting a molecule. For example, we have to know that the molecular weight of water which has two atoms of hydrogen and one atom of oxygen has a molecular weight of $18$ since the atomic weight of each hydrogen is $1$ and that of oxygen is $16$.

Complete step by step answer:
We need to know that the given molecule is aluminum nitrate $Al{(N{O_3})_3}$. We can get the atomic mass of the constituent elements from the periodic table. The elements are aluminum, nitrogen and oxygen. As we know that the atomic mass of aluminum, $Al$ is $27.0$ $g/mol$, that of Nitrogen, $N$is $14.01$ g/mol and that of oxygen, $O$ is 16.0 g/mol. Therefore, the molecular mass of aluminum nitrate $Al{(N{O_3})_3}$ is as follows: \left\\{ {27.0 + 3 \times 14.01 + 9 \times 16} \right\\}g/mol which is equal to $213g/mol$.
Hence the atomic mass of aluminum nitrate is $213g/mol$.

Note: The rules given above for the molecular mass of a compound is applicable only for molecules non-ionic compounds only which carry no charge. Also, there are different names for molecular mass of a compound. The name may be molar mass, molecular weight, gram formula mass, etc but they all account for the mass of one mole of a substance in grams per mole. It must also be noted that sometimes the atomic masses of the elements are not given but we can obtain them from the periodic table.