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    Stoichiometry refers to the study of relative quantities of reactants and/or products within a defined chemical system. It focuses on the relationships among quantities of reactants and products usually forming ratios of positive integers due to the nature of the bonded atoms. For example, in the combustion of methane (CH4), exactly 1 mole of methane reacts with 2 moles of oxygen to form 1 mole of carbon dioxide and 2 moles of water:

    CH4(g) + 2O2(g) --> CO2(g) + 2H2O(l)

    Considering the relative abundances of reactants and products is a specific branch of stoichiometry called ‘reaction stoichiometry.’ In the example above, reaction stoichiometry describes the 1:2:1:2 ratio of molecules CH4, O2, CO2 and H2O. These ratios can be used to determine values such as the percentage yield of products under different conditions, the presence of a limiting reagent, and even predict the behavior of certain elements under experimental conditions.

    Thus, understanding the fundamentals of stoichiometry can help calculate the desired quantitative data regarding chemical reactions, as well as other value which do not pertain to chemical reactions, such as the examination of elements within compounds and the behavior of gases.

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    BrainMass Categories within Stoichiometry

    Reaction Stoichiometry

    Solutions: 46

    Reaction Stoichiometry refers to the examination of the relative abundances of reactants and products in a chemical reaction within a defined system.

    Composition Stoichiometry

    Solutions: 8

    Composition Stoichiometry refers to the examination of the relative abundances of elements within chemical compounds.

    Gas Stoichiometry

    Solutions: 16

    Gas Stoichiometry refers to the examination of the relative proportions of reactants and products in a chemical reaction involving gases.

    Stoichiometry of Combustion

    Solutions: 3

    Stoichiometry of Combustion refers to the examination of the relative proportions of fuel and oxygen required to carry out a complete combustion reaction.

    Law of Definite Proportions

    Solutions: 1

    The Law of Definite Proportions states that a chemical compound always contains exactly the same proportion of elements by mass.


    Law of Multiple Proportions

    Solutions: 1

    The Law of Definite Proportions states that when two different elements combine to form more than one compound, the quantity of one element combined with a fixed amount of the other element, exhibits a simple whole number ratio.

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