1. ICP Do Now Get out your graph from the Icy Hot Lab Questions:
1) How are particles arranged differently in different phases of matter?
2) How do particles move differently in different phases of matter?
3) What is the difference between kinetic/thermal energy and interaction energy?
Objective: Students can describe the difference in particle arrangement and motion as well as describe changes in energy that occur during phase changes.

2. Exit Ticket- matching, write Ei or Eth for each word/phrase
Changes temperature
Changes phase
Ice is melting, so energy is added to this account
Water is increasing in temperature, so energy is added to this account
Water is boiling (turning from liquid to gas), so energy is added to this account)

3. How to represent the role of energy in physical change
Energy Bar Charts
How to represent the role of energy in physical change
© Modeling Chemistry 2007

4. Constructing an energy bar chart

5. 1. Determine what is in the system
Consider this example
A cup of hot coffee cools as it sits on the table.
Everything else makes up the surroundings
cup coffee

6. 2. Choose bars for Eth depending on temperature
Choice of bars for Eth arbitrary, but consistent.
2 bars= room temp and 1 bar=cold
Temp < 0˚C should be < 1 bar.

7. A cup of hot coffee cools as it sits on the table.
cup coffee

8. 3. Choose bars for Ei solids < liquids < gases Solids = 1 bar
Liquids = 2 bars
Gases = 4 bars

9. Assign values to Ei
Use two Ei bars before and after

10. 4. Is Ech is involved?
Do we change substances?

11. 5. Now show energy transfer
Does final or initial have more bars?
6 bars
-2 bars =
4 bars

12. A tray of ice cubes (-8 ˚C) is placed on the counter and becomes water at room temperature

13. Account for Energy Energy must flow into system via heating 1.5 bars

14. 3. A tray of water (20 ˚C) is placed in the freezer and turns into ice cubes (- 8 ˚C)
4. Where does the energy that leaves the system in #3 go? How does this energy transfer affect the room temperature in the kitchen? Do you have any experience that supports your answer?

15. An ice cube is placed in a glass of room temperature (25 ˚C) soft drink. Do separate bar charts for the ice cube and the soft drink.
Describe how the arrangement and the motion of the molecules in each system change from the initial to the final state.
Ice cube
Soft drink

16. 1. Temperature - Time During a State Change
Phase Change
Temperature (C)
Time (s) A B C D F E
1. Temperature - Time During a State Change

17. At each labeled point (A, B, C…) on the graphs draw
a particle diagram to show the arrangement of matter particles
a qualitative energy bar graph
Between each pair of labeled points (A-B, B-C, C-D…), write or draw
the state(s) of matter that are present
the change that is occurring (ex: temperature change, melting, condensing…)
an energy flow diagram showing how the energy of the system is changing (is it by working, heating, or radiating? is being energy transferred into or out of the system?)