Q.Calculate the mass of potassium chlorate required to liberate 6.72 dm3 of oxygen at STP. Molar mass of KClO3 is 122.5 g mol-1. (Ans. 24.5 g)

Stoichiometry is the calculation of the quantities (masses, moles or volumes) of reactants consumed and products formed in a chemical reaction, using the mole-ratio relationships implied by the reaction and, where mass is involved, the law of conservation of mass. Even a simple case — such as working out how much oxygen must have combined with a known mass of carbon to produce a known mass of carbon dioxide — is a stoichiometric calculation: since mass can neither be created nor destroyed, the mass of oxygen consumed must simply equal the mass of carbon dioxide produced minus the mass of carbon that reacted. M …