1. A. Phase Changes Sublimation solid  gas
v.p. of solid equals external pressure
EX: dry ice, mothballs, solid air fresheners

2. B. Phase Diagrams
Show the phases of a substance at different temps and pressures

3. Water vs. Carbon Dioxide
B. Phase Diagrams
Water vs. Carbon Dioxide

4. C. Heating Curves Gas - KE  Boiling - PE  Liquid - KE 
Melting - PE 
Solid - KE 

5. C. Heating Curves Temperature Change change in KE (molecular motion)
Phase Change
change in PE (molecular arrangement)
temp remains constant

6. C. Heating Curves Heat of Fusion (Hfus)
energy required to melt or freeze 1 mole of a substance at its m.p./f.p.
Hfus of ice = kJ/mol
To freeze (or melt) one mole of ice, you need to remove or put in kJ of energy (heat)

7. C. Heating Curves Heat of Vaporization (Hvap)
energy required to boil or condense 1 mole of a substance at its b.p./c.p.
Hvap for water = kJ/mol
usually larger than Hfus…why?
EX: sweating, steam burns

8. D. Properties of Water Hfus of ice = 6.009 kJ/mol
Hvap for water = kJ/mol
To calculate the amount of heat energy required to melt or freeze a substance:
convert grams to moles
multiply by molar heat of fusion or vaporization

9. D. Properties of Water
How much heat energy is required to melt 25 grams of ice at 0oC to liquid water at a temperature of 0oC?
ice
6.009 kJ
1 mol H2O
25 g H2O
1 mol H2O
18.02 g H2O
= 8.3 kJ

10. D. Properties of Water
How much heat energy is required to change grams of liquid water at 100oC to steam at 100oC?
steam
40.79 kJ
1 mol H2O
500.0 g H2O
1 mol H2O
18.02 g H2O
= 1132 kJ