Q.24 g of carbon reacts with some oxygen to make 88 grams of carbon dioxide. Find out how much oxygen must have been used. (Ans. : 64.0 )

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 …