What mass of the compound CrO3 (M = 100.0) contains 4.5x10^23 oxygen atoms?
According to Avogadro 1 mol of a substance contains `6.022xx10^23` atoms.
Here we have `4.5xx10^23` atoms of oxygen.
`CrO_3:O = 1:3`
So we have `(4.5xx10^23)/3` atoms of `CrO_3` in the compound.
Amount of `CrO_3` moles
So we have 0.25 moles of `CrO_3` in `4.5xx10^23` atoms of Oxygen in `CrO_3` .
Mass of `CrO_3 = 0.25molxx100g/(mol) = 25g`
So we need 25g of `CrO_3` .