Molar mass P2O5 = 31 x 2 + 16 x 5 => 142 g/mol
142 g ---------------- 6.02 x 10²³ molecules
0.930g g ------------ ( molecules )
molecules = 0.920 x ( 6.02 x 10²³ ) / 142
molecules = 5.53 x 10²³ / 142
= 3.89 x 10²¹ molecules
1 molecule P2O5 -------------------------- 7 atoms
3.89 x 10²¹ molecules -------------------- ( atoms )
atoms = ( 3.89 x 10²¹) x 7 / 1
atoms = 2.72 x 10²² atoms of P2O5
