# Exercise 5 | The periodic table and Chemical Periodicity

Find the empirical formula of a compound containing 1.92 grams of Mn and 1.12 grams of oxygen.

nMn = $\frac{{\mathrm{m}}_{\mathrm{Mn}}}{{\mathrm{M}}_{\mathrm{Mn}}}$ = $\frac{1.92}{54.94}$ = 3.49 x 10-2 g.mol-1

nO = $\frac{{\mathrm{m}}_{\mathrm{O}}}{{\mathrm{M}}_{\mathrm{O}}}$ = $\frac{1.12}{16.0}$ =  7.00 x 10-2 g.mol-1

nMn = 2 nO, the empirical formula of this compound is MnO2