As a consequence, chemists always prefer to write balanced chemical reactions . Balanced chemical reactions are usually written with the lowest integral number of molecules possible on each side, as in the above example. The two forms are equivalent in terms of the ratio of moles of one substance to moles of another. The ratios of moles of substances involved in any balanced chemical reaction are identical to the ratios of moles in any multiple or submultiple of the balanced chemical reaction . Many useful chemical properties are extensive properties.
Extensive properties are directly proportional to amount of substance.
The amount of energy produced by an automobile engine depends directly on the amount of fuel consumed, as do the mass and volume of air required and the mass and volume of exhaust produced. Chemists usually express these extensive properties in an intensive way, either as per mole of some specified substance or per mole of some specified reaction . The amount of carbon dioxide produced in the combustion of carbon monoxide is one mole of CO 2 per mole of carbon monoxide or two moles of CO 2 per mole of oxygen. Failure to be specific in this regard is probably the most significant reason for major errors in chemical stoichiometric calculations, both for students and experienced chemists. We can compute the number of moles of silver metal producible from 1.25 moles of silver sulfide, Ag 2 S, and compare it with the number of grams of silver metal producible from 1.25 grams of silver sulfide.