Question

How many oxygen atoms are in 0.07 mol of dinitrogen pentoxide (N2O5)? Answer in units of atoms

Answer 1

There are 6.02E23 molecules in 1 mol so there are 0.07 x 6.02E23 molecules in 0.07 mols. Since there are 5 O atoms in 1 molecule of N2O5, # O atoms will be 5x the number of molecules N2O5.