Lesson 2: Types of Energy Changes

• Types of Energy Changes

  • Temperature change
  • Phase change
  • Chemical changes (reactions)
  • Nuclear change
• Heat


  The amount of energy exchanged between a system and its surroundings
• Factors affecting heat change involving a temperature change

  • Mass (m) of the material
  • Temperature difference (∆T)
  • Nature of the material (type and state)
• Heat capacity (C)

  The quantity of heat required to change the temperature of an object or substance by one degree Celsius
• Specific heat capacity (c)

  The quantity of heat required to change the temperature of one gram of a substance by one degree Celsius
• Substances with higher specific heat capacity can absorb or release more energy than substances with lower specific heat capacity
• 1 calorie = 4.184 J
• For liquid water, c = 4.184 J/(g∙C); for ice, c = 2.01 J/(g∙C)
• Q

  Heat (J)
• m

  Mass of substance (g)
• C

  Heat capacity (J/C)
• c

  Specific heat capacity (J/(g ∙ C))
• ∆T

  T final - T initial (C)
• If delta T is negative, the reaction is endothermic
• If delta T is positive, the reaction is exothermic
• if Q is positive, it is endothermic, but if Q is negative, it is exothermic