6: Quantities in Chemical Reactions
- Page ID
- 17326
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.
- 6.1: Formula Mass
- Formula masses of ionic compounds can be determined from the masses of the atoms in their formulas.
- 6.2: The Mole
- A mole is \(6.022 \times 10^{23}\) things.
- 6.3: Atomic and Molar Masses
- The mass of moles of atoms and molecules is expressed in units of grams.
- 6.4: Mole-Mass Conversions
- It is possible to convert between moles of material and mass of material.
- 6.5: Mole-Mole Relationships in Chemical Reactions
- The balanced chemical reaction can be used to determine molar relationships between substances.
- 6.6: The Law of Conservation of Matter
- The amount of matter in a closed system is conserved.
- 6.7: Balancing Chemical Equations
- Chemical reactions are represented by chemical equations that list reactants and products. Proper chemical equations are balanced; the same number of each element’s atoms appears on each side of the equation.
- 6.8: Bond Energies and Chemical Reactions
- Atoms are held together by a certain amount of energy called bond energy. Chemical processes are labeled as exothermic or endothermic based on whether they give off or absorb energy, respectively.
- 6.9: Energetics of Biochemical Reactions
- Energy to power the human body comes from chemical reactions.
- 6.10: Energies, Kinetics, and Catalysts
- Reaction energy diagrams summarize the important information about a reaction in a single graph. The y-axis represents the energy and the x-axis represents the reaction progress (time). For an exothermic reaction, the products are lower in energy than the reactants resulting in a release of heat. For an endothermic reaction, the products are higher in energy than the reactants requiring the constant addition of heat to keep the reaction going.
- 6.11: 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.
- 6.12: 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.