Thermochemistry

• Heat (Q)


  The energy transferred from one object to another due to their temperature difference
• Work (W)


  The energy transferred when an object is moved against force
• Thermodynamics is the study of the energy changes that accompany all processes, whether chemical or physical
• Thermochemistry is the study of heat and energy changes that accompany chemical transformation in matter
• First Law of Thermodynamics

  The Law of Conservation of Energy states that energy can neither be created nor destroyed, it can only be transformed from one kind to another
• Exothermic reaction


  A reaction that releases energy
• Endothermic reaction


  A reaction that absorbs energy
• Classify as endothermic or exothermic


  • Reaction
• Calorimetry


  Measuring energy changes in chemical reactions or it measures the energy
• Heat of reaction


  The total amount of heat obtained, which is actually the energy change when the reaction occurs
• Enthalpy change (H)


  The heat transferred by a process that occurs at constant pressure
• For most reactions, heats of reactions are good approximations of the enthalpy changes and are often referred to interchangeably
• Calorimetry


  The measurement of the amount of heat evolved or absorbed when a process or chemical reaction takes place
• System


  The limited, defined part of the universe
• Universe


  The observable, physical world
• Surroundings


  All parts of the universe not included in the defined system
• Internal Energy (U)


  The energy contained within the system, which can be changed by heating the system, doing work on it, or adding or taking away matter
• Q > 0 (+) heat is absorbed by the system (endothermic)
• Heat

   is the energy transferred from  one object to another due to their  temperaturedifference.
• Q < 0 (-) heat is released by the

  system (exothermic)


  .
• W > 0 (+) is work done on the

  system
• W < 0 (-) is work done by the

  system