Question

The total number of atoms in 26.7g of oxygen gas is __________x10^24.

Answer 1

First you need to find the number of moles of oxygen gas that are made up by 26.7g of oxygen.(Note: Oxygen gas is Diatomic). Once you have the moles of oxygen gas multiply by 6.022x10^23

Answer 2

Use the relation:

\[n = \frac{ m }{ M} = \frac{ N_{atoms} }{ N_{Avogadro} }\]

As you can see number of moles (n) can be expressed in terms of a mass, or in terms of numbers of atoms.

So use the n = m/M to convert mass to moles. Then use this answer of n and solve for N of atoms. with the second formula.