Stoichiometry (pronounced /ˌstɔɪkiˈɒmɨtri/, STOY-kee-AHM-ə-tree) is a branch of chemistry that deals with the quantitative relationships that exist between the reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of whole numbers. For example, in a reaction that forms ammonia (NH3), exactly one molecule of nitrogen (N2) reacts with three molecules of hydrogen (H2) to produce two molecules of NH3:
N2 + 3H2 → 2NH3
Stoichiometry can be used to calculate quantities such as the amount of products that can be produced with given reactants and percent yield (the percentage of the given reactant that is made into the product). Stoichiometry calculations can predict how elements and components diluted in a standard solution react in experimental conditions. Stoichiometry is founded on the law of conservation of mass: the mass of the reactants equals the mass of the products.
While almost all reactions have integer-ratio stoichiometry in amount of matter units (moles, number of particles), some nonstoichiometric compounds are known that cannot be represented by a ratio of well-defined natural numbers. These materials therefore violate the law of definite proportions that forms the basis of stoichiometry along with the law of multiple proportions. (wikipedia)
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See Also
Addition
Arithmetic
Chord
Division
Geometry
Interval
law of multiple proportions
law of constant composition
Law of Definite Proportions
Mathematics
Multiplication
Music
Number
Proportion
Propositions of Geometry
Quantum Arithmetic
Ratio
Subtraction