# How many oxygen atoms are there in a 32*g mass of oxygen gas?

Nov 23, 2016

There are $2 \times {N}_{A}$ oxygen atoms in a $32 \cdot g$ mass of dioxygen.
And ${N}_{A}$ $=$ $\text{Avogadro's number}$ $=$ $6.022 \times {10}^{23} \cdot m o {l}^{-} 1$
Note that ${N}_{A}$ oxygen atoms have a mass of $16.0 \cdot g$.
But ${N}_{A}$ oxygen MOLECULES, i.e. dioxygen, have a mass of $32.0 \cdot g$.