CHEM101: General Chemistry I

6.1: Energy

• 6.1.1: Energy Terminology

  • Stephen Lower's "General Chemistry Virtual Textbook: Energy, Heat, and Work"

    Read this webpage. Pay close attention to how the system and surroundings are defined; this will determine the direction of energy flow in thermodynamic systems.
    

• 6.1.2: Chemical Energy and Enthalpy

  • Stephen Lower's "General Chemistry Virtual Textbook: Chemical Energetics and Thermodynamics - Part 3: Molecules as Energy Carriers and Converters"

    Read this webpage. Make sure you can follow the concept map at the bottom of the page, which relates potential and kinetic chemical energy to enthalpy of a system.
    

  • Khan Academy: "Enthalpy" and "Heat of Formation" Page

    Watch these videos to reinforce the concepts covered in the reading assignment. The enthalpy of a system is the energy contained in its chemical bonds plus any pressure-volume work the system can do. 
    

• 6.1.3: Hess's Law and Calorimetry

  • Stephen Lower's "General Chemistry Virtual Textbook: Chemical Energetics and Thermodynamics - Part 4: Thermochemistry and Calorimetry"

    Read this webpage. Calorimetry is used to measure the change in enthalpy of reactions in a laboratory setting. Since enthalpy is a state function, Hess's law is applied to calculate the change in enthalpy from literature values.
    

  • Khan Academy: "Hess's Law and Reaction Enthalpy Change" and "Hess's Law Example" Page

    Watch these two videos to reinforce the concepts covered in the reading assignment.
    

• 6.1.4: Bond Energy

  • Stephen Lower's "General Chemistry Virtual Textbook: Chemical Energetics and Thermodynamics - Part 5: Some Applications of Enthalpy and the First Law"

    Read this webpage. Using bond energy to calculate the enthalpy of reaction is not particularly accurate because energies are affected by each molecule's unique surroundings, such as intermolecular forces. For this reason, energies are only an average across many different reactions.