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7: Quantities in Chemical Reactions

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    So far, we have talked about chemical reactions in terms of individual atoms and molecules. Although this works, most of the reactions occurring around us involve much larger amounts of chemicals. Even a tiny sample of a substance will contain millions, billions, or a hundred billion billions of atoms and molecules. How do we compare amounts of substances to each other in chemical terms when it is so difficult to count to a hundred billion billion? Actually, there are ways to do this, which we will explore in this chapter. In doing so, we will increase our understanding of stoichiometry, which is the study of the numerical relationships between the reactants and the products in a balanced chemical reaction.

    • 7.1: Formula Mass
      Formula masses of ionic compounds can be determined from the masses of the atoms in their formulas.
    • 7.2: The Mole
      A mole is \(6.022 \times 10^{23}\) things.
    • 7.3: Atomic and Molar Masses
      The mass of moles of atoms and molecules is expressed in units of grams.
    • 7.4: Mole-Mass Conversions
      It is possible to convert between moles of material and mass of material.
    • 7.5: Mole-Mole Relationships in Chemical Reactions
      The balanced chemical reaction can be used to determine molar relationships between substances.
    • 7.6: Energetics of Biochemical Reactions
      Energy to power the human body comes from chemical reactions.
    • 7.7: Factors Affecting Reaction Rates
      The rate of a chemical reaction is affected by several parameters. Reactions involving two phases proceed more rapidly when there is greater surface area contact. If temperature or reactant concentration is increased, the rate of a given reaction generally increases as well. A catalyst can increase the rate of a reaction by providing an alternative pathway that causes the activation energy of the reaction to decrease.
    • 7.8: Catalysis
      Catalysts affect the rate of a chemical reaction by altering its mechanism to provide a lower activation energy. Catalysts can be homogenous (in the same phase as the reactants) or heterogeneous (a different phase than the reactants).
    • 7.9: Equilbria and Le Chatelier's Principle
      Increasing the temperature of a system in dynamic equilibrium favors the endothermic reaction. The system counteracts the change by absorbing the extra heat. Decreasing the temperature of a system in dynamic equilibrium favors the exothermic reaction. The system counteracts the change by producing more heat.
    • 7.10: Chapter Summary
      To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms in the following summary and ask yourself how they relate to the topics in the chapter.

    7: Quantities in Chemical Reactions is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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