Cooling curve

• How many "sections" are there on a heating/cooling curve?

  5
• What are the 2 "types" of sections on a heating/cooling curve?

  Diagonal and plateau
• On a "diagonal" section of a heating curve, what change does the energy that is ADDED create?

  It increases the temperature
• On a "diagonal" section of a cooling curve, what change does the energy that is RELEASED create?

  It decreases the temperature
• On a "plateau" section of a heating curve, what change does the energy ADDED create?


  Phase change (change of state)
• On a "plateau" section of a cooling curve, what change does the energy RELEASED create?


  Phase change (change of state)
• What phase change occurs on the FIRST "plateau" of a heating curve?

  Melting
• What phase change occurs on the FIRST "plateau" of a cooling curve?

  Freezing
• What phase change occurs on the SECOND "plateau" of a heating curve?

  Boiling (Vaporization, Evaporation)
• What phase change occurs on the SECOND "plateau" of a cooling curve?

  Condensation
• Does the temperature EVER increase during a phase change? Why?

  No. All the energy is being used to complete the phase change and there is not any extra available to change the temperature.
• What is the name of the FIRST "plateau"

  Heat of fusion
• What is the name of the SECOND "plateau"

  Heat of vaporization
• What phase change can occur on a heating curve during the Heat of Fusion?

  Melting
• What phase change can occur on a cooling curve during the Heat of Fusion?

  Freezing
• What phase change can occur on a heating curve during the Heat of Vaporization?

  Boiling (Vaporization, Evaporation)
• What phase change can occur on a cooling curve during the Heat of Vaporization?

  Condensation
• Are both "plateaus" on a heating/cooling curve the same length? If not, how do they differ?

  No. The heat of fusion is shorter than the heat of vaporization.
• What accounts for the difference in lengths of the Heat of Fusion vs the Heat of Vaporization?

  For heat of fusion, you only have to be able to melt the substance enough to allow the molecules to slide past each other. However, on heat of vaporization you have to be able to separate the molecules completely.
• What is the boiling point of water?

  100 C
• What is the freezing point of water?

  0 C
• What is the melting point of ice?

  0 C
• What is the condensation point of water?

  100 C
• As you move up the heating curve is energy added or released?

  Added
• As you move up the heating curve is it endothermic or exothermic?

  Endothermic
• As you move down the cooling curve is energy added or released?

  Released
• As you move down the cooling curve is it endothermic or exothermic?

  Exothermic
• Is melting endothermic or exothermic?

  Endothermic
• Is freezing endothermic or exothermic?

  Exothermic
• Is boiling endothermic or exothermic?

  Endothermic
• Is condensation endothermic or exothermic?

  Exothermic
• True or False:

  On any heating curve, energy is added and therefore it is always endothermic.

  True
• True or False:

  On any cooling curve, energy is released and therefore it is always exothermic.

  True
• True or False:

  A cooling curve is the reverse of a heating curve - the only difference is the sign assigned to the calculated value.

  True
• What formula do you use to calculate the energy change on the "diagonal" sections of a heating/cooling curve?

  q = mc delta T
• What formula do you use to calculate the energy change on the FIRST "plateau" of a heating/cooling curve?

  qf = mHf
• What formula do you use to calculate the energy change on the SECOND "plateau" of a heating/cooling curve?

  qv = mHv
• If you have water at -20C and heat it to 80C - how many calculations do you have to do to get your final amount of energy added?


  3 (heat to 0, phase change, heat to 80)
• If you have ice at 0C and heat it to 80C - how many calculations do you have to do to get your final amount of energy added?

  2 (phase change, heat to 80)
• Endothermic means that heat is _____________?

  Added