If 500 g of KCIO decomposes and produces 303 KCI how many grams O2 are produced?

Moles of KCl produced = (303 g)/(74.55 g/mol) = 4.07 mol

Moles of O2 produced from 2 moles of KClO3 = 3 mol

Therefore 4.07 mol KCl produced

= (4.07 mol/2) * 3 mol = 6.11 mol O2

Mass of O2 produced = (6.11 mol) * (32 g/mol) = 195.52 g.