1. Heating Curves
Ice melts by absorbing heat, but without increasing temperature.
0oC solid  0oC liquid
(avg KE stays same)
HOW?
…by changing phase.

2. added heat breaks IMAFs & increases distance (↑PE)
Heating Curve
same temp during phase change
(same KEavg)
What happens to added heat?
vaporize/condense
added heat breaks IMAFs & increases distance (↑PE)
melt/freeze

3. Heating Curve of Water KE PE KE PE
handout
KE PE
heat raises Temp
endothermic
(↑KE)
gas
exothermic
KE PE
boiling
100oC
boiling point
condensation
(↑PE)
heat breaks IMAFs
liquid
Temp (oC)
heat breaks IMAFs
(↑KE)
heat raises Temp
(↑PE)
melting
melting point
0oC
freezing
freezing point
solid
(↑KE)
heat raises Temp
Heat Added (or Time)

4. Heating Curve of Water heat of vaporization heat of fusion
handout
Why is ∆Hvap >>> ∆Hfus?
heat of vaporization
lg takes more energy to break IMAFs than sl
gas
(2260 J)
100oC
(∆Hvap)
heat required to vaporize (or condense)
liquid
Temp (oC)
heat of fusion
(418 J)
q = mcDT
(c = 4.18 J/goC)
(334 J)
0oC
(∆Hfus)
heat required to melt (or freeze)
solid
Heat Added (or Time)

5. The phase change sequence is reversible.
Cooling Curve of Water
gas
condensation
100oC
boiling
liquid
The phase change sequence is reversible.
Temp (oC)
freezing
0oC
melting
solid
Heat Removed (or Time)

6. animation

7. Quick Quiz!
Complete WS 1 #3-8
Complete WS 2