Hence, a balanced chemical equation gives lot of quantitative information about a chemical reaction

The method describe for determining atomic and molecular masses constitute the beginning of a general approach to chemical calculations and quantitative methods called chemical stoichiometry. It is the area of chemistry and chemical technology on which the determination of the quantities of reactants or products of a chemical reaction is based. Here the quantity of substance ranges from laboratory scale (gm, milligram) to production scale (few Kg to several tons). In all such cases the atoms and molecules combine in definite ratios in terms of number and in terms of their amounts. It is also called as reaction stoichiometry as it is the calculation of measurable relationships of reactants and products in a balanced chemical equation.

Hence, a balanced chemical equation gives lot of quantitative information about a chemical reaction. It also provides a quantitative relationship between masses of reactants and products. Quantity of a substance consumed or produced can be determined only if we use a balanced chemical equation. Stoichiometry rests upon the different laws like law of conservation of mass, the law of constant composition and also the law of multiple proportions. We already know that chemical reactions combine on definite ratio of chemicals. As chemical reactions can neither create nor destroy matter, nor can it transmute one element into another so the amount of each element must be the same throughout the chemical reaction. The amount of elements on the reactant side has to be equal to the amount of elements on the product side. Stoichiometry is also used to balance chemical equations. It is often used for molar proportion of elements in stoichiometric compounds. So the compounds for which the molar proportions may not be a whole number are non-stoichiometric compounds.

Stoichiometry may not only be used to balance chemical equations but also used in conversions from one unit to another like converting from grams to moles or from grams to milliliters. It is used to find the right amount of reactants that is to be used in a chemical reaction. The extent of the reaction can be regarded as real product meaning one molecule of each is produced every time the reaction event would occur. The stoichiometric coefficient represents the degree to which any chemical species would participate in a chemical reaction. Negative coefficients are assigned to reactants as they are consumed and positive ones to the products. As we know that any reaction may be viewed as going in a reverse direction. Whether a reaction will proceed in a forward or reverse direction actually depends upon the amount of substances present in a given reaction at any given time, determining whether equilibrium lies to the right or the left.