4TH-GENCHEM-2

• Thermochemistry


  The study of heat and energy related to various physical transformations and chemical reactions
• During the reaction


  1. Energy can be absorbed (endothermic)

  2. Energy can be released (exothermic)
• Thermochemistry


  • Mainly concerned with a change in energy mainly regarding an exchange of energy of a system with its surroundings
• According to the laws of thermodynamics, the energy of an isolated system remains constant
• If the system is not isolated, then during any chemical reaction, the energy is conserved
• Thermochemistry


  Useful to understand energy changes, heat changes and the spontaneity of reactions
• Common to all reactions

  • Heat
  • Work
  • Heat-work relationships
• During the reaction

  1. Work can be done on the system

  2. Work can be done by the system

  3. Heat can be absorbed

  4. Heat can be given out of the system
• Calorimetry


  Deals with the measurement of the state of a body with respect to the thermal aspects in order to examine its physical and chemical changes
• Calorimeter


  Used to measure the thermal changes of a body
• System


  The part of the universe which excludes the system is called the surroundings. A boundary separates the system and surroundings.
• Open System


  • Exchanges energy and matter with its surroundings. Example: A vessel of hot water.
• Closed System


  • Can exchange only energy and not matter. For example: balloons.
• Isolated System


  • Cannot exchange matter or energy with its surroundings. Example: an insulated bomb calorimeter. An isolated system is either a physical system or a thermodynamic system.