Potassium chlorate (KClO3) decomposes upon heating, with or without a catalyst, to produce potassium chloride and oxygen. The balanced chemical equation for the decomposition of KClO3 is:
2KClO3 → 2KCl + 3O2
From the stoichiometry of the reaction, it can be said that
When 2 moles of KClO3 is decomposed, number of moles of oxygen produced is 3
Therefore, when 0.8 moles of KClO3 is decomposed, number of moles of oxygen produced will be = 3*0.8/2 = 1.2
Hence, 1.2 moles of oxygen would be produced from 0.8 moles of KClO3.