What mass of KClO3 must be decomposed in order to generate 5.00 L of oxygen, measured at STP?

The mass of KClO3 must be decomposed in order to generate 5.00 L of oxygen, measured at STP is 18.2 g KClO3. This is a prime example of Stoichiometry. Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the total mass of the products, leading to the insight that the relations among quantities of reactants and products typically form a ratio of positive integers. KClO3 is chemical formula for potassium chlorate. Potassium chlorate is a white crystalline solid, and forms a very flammable mixture with it is combined with combustible materials.