Physics 7A DL 15 Overview DL 15
Brief Overview
These Activities continue work on the Thermodynamic Model and begin in the last Activity an
introduction to states, microstates, and probabilities.
Activities
Activity 4.6 Follow-up of DL 14 FNTs
Purpose:
• To provide more opportunities to work with the constructs and relationships of the
Thermodynamic Model simultaneously with other models
Learning Outcomes:
• Deeper understanding of how the Thermodynamic Model provides an explanation for the
observation that 𝐶𝑝 is always significantly larger than 𝐶𝑣 for gases, but is only slight larger for
most solids and liquids.
• Become confident in your ability to use multiple models together along with state diagrams to
answer questions and get numerical values.
• More proficient working with state diagrams.
• Ability to determine work and heat (using information from other models as appropriate) from PV
diagrams.
Activity 4.7 States, Microstates, and Probabilities
Purpose:
• To provide an opportunity to work with the constructs and relationships of the Thermodynamic
Model having to do with states and microstates.
Learning Outcomes:
• Understanding of the concepts of state and microstate of a system composed of a number of
independent “entities”.
• Understanding of the concept of the probability of being in a particular state being equal to the
ratio of the number of microstates associated with that state to the total number of microstates.
• Ability to determine states and microstates of simple systems and to compute probabilities of
being in a particular state.
Unit 4: Models of Thermodynamics DL 15
, Physics 7A Activity 4.6 DL 15
Follow-up of FNTs
A) FNT 1:
a) Quickly summarize what you did to complete Activity 4.4 C) 1-3. Put this on the board. Make sure
everyone in your group can explain.
b) Quickly summarize what you did to complete Activity 4.4 D) 1-2. Put this on the board. Make sure
everyone in your group can explain.
c) How do your answers in C) 3) and D) 2) compare?
d) Develop an explanation for why the heat capacity of any gas, monatomic or not, or ideal or not, will
be greater when measured at constant pressure than at constant volume. Explain why this difference
is small for liquids and solids compared to gases.
Whole Class Discussion
B) FNT 2:
Here are the values of heat that you should get for each process:
Ha→ b = 5.3 kJ
a: liquid at 30C
H b→ c = 40.7 kJ
b: liquid at 100C
c: gas at 100C H c→ d = -2.4 kJ
d: gas at 30C H a→ d = 43.6 kJ
How did this example illustrate the path-independence of state functions?
Whole Class Discussion
C) FNT 3:
Work, change in internal energy, and heat for this process (for n = 3 moles):
W = -1150 J U = 997 J Q = 2147 J
1) Show how to find the magnitude and sign of the work for this process.
2) Show how to find the change in internal energy for this process.
3) Show how to find the heat transferred in this process. Outline an explanation for why the heat is
usually the last thing to determine when using a PV diagram.
4) Could you answer these questions if the temperatures were not provided? Why or why not?
Whole Class Discussion
Continue to Next Page
Unit 4: Models of Thermodynamics DL 15
Brief Overview
These Activities continue work on the Thermodynamic Model and begin in the last Activity an
introduction to states, microstates, and probabilities.
Activities
Activity 4.6 Follow-up of DL 14 FNTs
Purpose:
• To provide more opportunities to work with the constructs and relationships of the
Thermodynamic Model simultaneously with other models
Learning Outcomes:
• Deeper understanding of how the Thermodynamic Model provides an explanation for the
observation that 𝐶𝑝 is always significantly larger than 𝐶𝑣 for gases, but is only slight larger for
most solids and liquids.
• Become confident in your ability to use multiple models together along with state diagrams to
answer questions and get numerical values.
• More proficient working with state diagrams.
• Ability to determine work and heat (using information from other models as appropriate) from PV
diagrams.
Activity 4.7 States, Microstates, and Probabilities
Purpose:
• To provide an opportunity to work with the constructs and relationships of the Thermodynamic
Model having to do with states and microstates.
Learning Outcomes:
• Understanding of the concepts of state and microstate of a system composed of a number of
independent “entities”.
• Understanding of the concept of the probability of being in a particular state being equal to the
ratio of the number of microstates associated with that state to the total number of microstates.
• Ability to determine states and microstates of simple systems and to compute probabilities of
being in a particular state.
Unit 4: Models of Thermodynamics DL 15
, Physics 7A Activity 4.6 DL 15
Follow-up of FNTs
A) FNT 1:
a) Quickly summarize what you did to complete Activity 4.4 C) 1-3. Put this on the board. Make sure
everyone in your group can explain.
b) Quickly summarize what you did to complete Activity 4.4 D) 1-2. Put this on the board. Make sure
everyone in your group can explain.
c) How do your answers in C) 3) and D) 2) compare?
d) Develop an explanation for why the heat capacity of any gas, monatomic or not, or ideal or not, will
be greater when measured at constant pressure than at constant volume. Explain why this difference
is small for liquids and solids compared to gases.
Whole Class Discussion
B) FNT 2:
Here are the values of heat that you should get for each process:
Ha→ b = 5.3 kJ
a: liquid at 30C
H b→ c = 40.7 kJ
b: liquid at 100C
c: gas at 100C H c→ d = -2.4 kJ
d: gas at 30C H a→ d = 43.6 kJ
How did this example illustrate the path-independence of state functions?
Whole Class Discussion
C) FNT 3:
Work, change in internal energy, and heat for this process (for n = 3 moles):
W = -1150 J U = 997 J Q = 2147 J
1) Show how to find the magnitude and sign of the work for this process.
2) Show how to find the change in internal energy for this process.
3) Show how to find the heat transferred in this process. Outline an explanation for why the heat is
usually the last thing to determine when using a PV diagram.
4) Could you answer these questions if the temperatures were not provided? Why or why not?
Whole Class Discussion
Continue to Next Page
Unit 4: Models of Thermodynamics DL 15
