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Chemistry LibreTexts

5: Stoichiometry and the Mole

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  • We have already established that quantities are important in science, especially in chemistry. It is important to make accurate measurements of a variety of quantities when performing experiments. However, it is also important to be able to relate one measured quantity to another, unmeasured quantity. In this chapter, we will consider how we manipulate quantities to relate them to each other.

    • 5.1 Stoichiometry
      Quantities of substances can be related to each other using balanced chemical equations.
    • 5.2 The Mole
      The mole is a key unit in chemistry. The molar mass of a substance, in grams, is numerically equal to one atom’s or molecule’s mass in atomic mass units.
    • 5.3 Percent Composition, Empirical and Molecular Formulas
      The chemical identity of a substance is defined by the types and relative numbers of atoms composing its fundamental entities (molecules in the case of covalent compounds, ions in the case of ionic compounds). A compound’s percent composition provides the mass percentage of each element in the compound, and it is often experimentally determined and used to derive the compound’s empirical formula.
    • 5.4 The Mole in Chemical Reactions
      Balanced chemical reactions are balanced in terms of moles. A balanced chemical reaction gives equivalences in moles that allow stoichiometry calculations to be performed.
    • 5.5 Mole-Mass and Mass-Mass Calculations
      Mole quantities of one substance can be related to mass quantities using a balanced chemical equation. Mass quantities of one substance can be related to mass quantities using a balanced chemical equation. In all cases, quantities of a substance must be converted to moles before the balanced chemical equation can be used to convert to moles of another substance.
    • 5.6 Yields
      Theoretical yield is what you calculate the yield will be using the balanced chemical reaction. Actual yield is what you actually get in a chemical reaction. Percent yield is a comparison of the actual yield with the theoretical yield.
    • 5.7 Limiting Reagents
      The limiting reagent is that reactant that produces the least amount of product. Mass-mass calculations can determine how much product is produced and how much of the other reactants remain.

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