determine the mass in grams of 125 moles of neon
However make sure you get the atomic MASS not atomic NUMBER. If unsure, the mass is the bigger of the two. So for Neon: moles of neon = 125 Relative atomic mass of neon = 20 Rearranging formulma above gives: moles/relative atomic mass=mass in grams 125/20=6.25 grams Hope this helps.Source(s): Tim Burr Â· 7 years ago. need help finding the mass in grams of x number of moles of x Example: determine the mass in grams of 125 moles of neon I have no periodic table to refer to so I have no idea and even with one I have no idea Thanks. Update: Can anyone help explain it in easier terms to understand.