# How many atoms of oxygen are found in aluminum nitrate?

How many atoms of oxygen in one formula unit of $A l {\left(N {O}_{3}\right)}_{3}$? 9 atoms precisely.
In 1 formula unit of $A l {\left(N {O}_{3}\right)}_{3}$, there are (clearly!) 9 atoms of oxygen, 3 nitrogen atoms, and 1 aluminum atom. I have gone on before that the mole (${N}_{A}$, Avogadro's number) is simply a much larger number, i.e. ${N}_{A}$ $=$ $6.022 \times {10}^{23}$.
So, in 1 mole of $A l {\left(N {O}_{3}\right)}_{3}$ there are (9 $\times$ N_A) $O$ atoms precisely. What is the mass of 1 mol $A l {\left(N {O}_{3}\right)}_{3}$?