UNIT 6: THERMODYNAMICS – EXAM STUDY GUIDE
6.1 – Methods of Heat Transfer
Give examples of conduction, convection, and radiation. How can you tell these three apart?
6.1, 6.2, 6.3 Quiz – Multiple choice questions
6.1 Homework – All questions
6.1 and 6.2 Exit Ticket: #1, 2, 8
Conduction – heat transferred through a solid (movement of electrons)
Convection – heat transferred through a liquid or gas (expansion and circulation of molecules relating to density)
Radiation – heat transferred as a wave (e.g. heat emitted from sun, fires, lightbulbs, microwaves)
6.2 – Laws of Thermodynamics
What are the three laws of thermodynamics?
1st – Law of Conservation of Energy
Examples?
6.1, 6.2, 6.3 Quiz – fill in the blank (3 laws question #4), Short Answer #2
2nd – Law of Entropy
Examples?
6.1, 6.2, 6.3 Quiz – fill in the blank (3 laws questions #1, 2)
6.1 and 6.2 Exit Ticket - #5, 7
6.2 HW - #2,3,4,5
3rd – Third Law (nothing can reach absolute zero)
Examples?
6.1, 6.2, 6.3 Quiz – fill in the blank (3 laws question#3), Short Answer #1
Applications of the 1st Law: 𝛥𝐸 = 𝑄 + 𝑊
When is heat positive? Negative?
+: absorbed
-: released
When is work positive? Negative?
+: something else does work on system
-: system does work, work done by system
Example problems? [Get from notes / quizzes]
6.1, 6.2, 6.3 Quiz: Short Answer #3
Bellringer #6-8
6.2 HW: #1, 8a*(includes W = mgΔh from unit 5)
6.1 and 6.2 Exit Ticket: #3
Heat Engines
Multiple processes:
1) Absorbs heat
2) Engine does work (releases energy)
3) Engine releases heat
Picture:
*Drawn in Class*
𝛥𝐸 = 0
0 = 𝑄𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 + 𝑊 + 𝑄𝑟𝑒𝑙𝑒𝑎𝑠𝑒𝑑
*NOTE: These equations for heat engines NOT provided on your exam!!!
Examples:
6.1, 6.2, 6.3 Quiz: Short Answer #4a
6.1 and 6.2 Exit Ticket: #4, 6 (first step of 2-step problem)
6.2 HW: #6
𝑊
𝑊
Efficiency: 𝑒𝑓𝑓 = 𝑄 = 𝑊+𝑄𝑟𝑒𝑙
𝑖𝑛
***NOTE: equations NOT provided on your exam!!!
6.1, 6.2, 6.3 Quiz: Short Answer #4b, 5
6.1 and 6.2 Exit Ticket: #6 (second step of 2-step problem)
6.2 HW: #7, 8b, 9*(includes W = Fd from Unit 5)
6.3 – Energetic Properties of Matter
Rank the phases in order of increasing:
Potential Energy? ***WILL NOT BE ON EXAM  In covering this in class, I stated solids = high PE and gases =
low PE; however, after discussions with students who were confused about adding PE on heating curves, I clarified
that solids have the most negative potential energy because of intermolecular force attractions, while ideal gases are
assumed to have have zero potential energy due to no intermolecular force attractions. Because of this, students
were confused since technically, solids still have less PE than liquids or gases. As a result, I will discuss and clarify in
class on Monday after the exam and will not test you on this topic. If, after you’ve mastered all other material in this
unit, you’d like to further investigate this topic yourself with visuals, please consult http://hyperphysics.phyastr.gsu.edu/hbase/hframe.html***
Kinetic Energy? (low) Solids  Liquids  Gases (high)
Entropy? (low) Solids  Liquids  Gases (high)
Draw and label a heating curve. Label phases and phase transitions, where KE is increasing, and where PE is increasing.
Legs A, C, E: increasing KE. Legs B, D: increasing PE
Practice Problems: 6.3 HW sheet that says “Chemistry” on it
6.1, 6.2, 6.3 Quiz: Fill in the blank up until the question about boiling point
6.4 – Specific Heat, Thermal Equilibrium, and Latent Heat
Important about specific heat: High specific heat requires more energy to change temperature (will have less ΔT)
Low specific heat requires less energy to change temperature (will have greater ΔT)
On a graph, high cp = small slope; low cp = large slope
What equation do you use when temperature is changing?
𝑄 = 𝑚𝑐𝑝 𝛥𝑇
Examples: 6.4 Quiz: #1, 2, 3a
6.4.1 Exit Ticket and Homework: All problems
What equation do you use when phase is changing?
𝑄 = 𝑚𝐿
Examples: 6.4.3 Homework: #1,2
How do you find these on a graph?
1) Determine leg of phase change on graph
2) Q = (Final heat absorbed on leg) – (Initial heat absorbed on leg); complete conversion to J if necessary
3) Plug into Q = mL to solve for L
Examples: 6.4.3 Homework: #3,4
6.4 Quiz: 3b
When two substances are mixed, what equation do you use? −(𝑚𝑐𝑝 𝛥𝑇)
= (𝑚𝑐𝑝 𝛥𝑇)
𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒1
𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒2
*NOTE: This equation will not be given to you!
Examples: 6.4.2 Homework: All problems
6.4 Quiz: #4
ADDITIONAL PROBLEMS TO WORK: Problems involving both phase change AND temperature change
1) ID phases present and temperatures for each phase (separated by melting/boiling point)
2) Calculate Q = mcpΔT for each phase
3) Calculate Q = mL for each phase change
4) Sum all Qs to obtain your total heat. Solve for unknown.
Examples: 6.4.3 HW: #5,6,7
6.4 Quiz: #5