4 Rb + O₂ → 2 Rb₂O
Number of moles Rb = 82.4 g / 85.47 g/mol = 0.964
Number of moles O₂ = 11.6 g / 32 g/mol =0.363
the ratio between Rb and O₂ is 4 : 1 so Rb is the limiting reactant
Moles Rb₂O = 0.964 / 2 = 0.482
Mass Rb₂O = 0.482 mol x 186.94 g/mol = 90.1 g
% yield = 39.7 x 100 / 90.1 = 44.1
