Find the mass of formula unit from # of atoms

Question

Find the mass of Al(NO3)3 from 1.50 x 10^22 Oxygen atoms.

I'm wondering if either way is correct?

1.50x10^22 O atoms x 1 formula unit Al(NO3)3 / 9 O atoms x 1 mol Al(NO3)3 / 6.02x10^23 fu Al(NO3)3 x

148.32g Al(NO3)3 / 1 mol Al(NO3)3

Or

1.5x10^22 O atoms x 1mol O / 6.02 x 10^23 O atoms x 1 mol Al(NO3)3 / 9 mol O x 148.32g (al(NO3)3 / 1mol Al(NO3)3

Just wondering if either way is correct.

Thank you!

Answer 1

I looks like you get the same answer no matter which way you do the calculations. Makes sense.