Difference between revisions of "PChem312 f20 w4"
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===Wednesday, Sept 9, 2020=== | ===Wednesday, Sept 9, 2020=== | ||
====Sec 2.9: Comparing Work/Indicator Diagrams==== | ====Sec 2.9: Comparing Work/Indicator Diagrams==== | ||
| − | |||
| + | =====Irreversible Work===== | ||
The following shows a ''PV diagram'', also known as an '''indicator diagram'''. The center figure is Fig. 2.7 in your text. The outside "cylinders" are my annotation to clarify the diagram. I have separated the "expansion" (irreversible, isothermal) work from the "compression" (irreversible isothermal) work. | The following shows a ''PV diagram'', also known as an '''indicator diagram'''. The center figure is Fig. 2.7 in your text. The outside "cylinders" are my annotation to clarify the diagram. I have separated the "expansion" (irreversible, isothermal) work from the "compression" (irreversible isothermal) work. | ||
| + | |||
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:[[File:PV_02_Irrev_IsoT_Exp.png|600px]] | :[[File:PV_02_Irrev_IsoT_Exp.png|600px]] | ||
| − | ::Starting at an initial state (P<sub>1</sub>, V<sub>1</sub>; red dot), when we remove the weight quickly, but do not allow the system to change volume, we find ourselves in a temporary/fictitious state (P<sub>2</sub>, V<sub>1</sub>; green dot). The irreversible work is then done under P<sub>1</sub> (P<sub>1</sub> < P<sub>2</sub>) ending in the final state (P<sub>1</sub>, V<sub> | + | |
| + | |||
| + | ::Starting at an initial state (P<sub>1</sub>, V<sub>1</sub>; red dot), when we remove the weight quickly, but do not allow the system to change volume, we find ourselves in a temporary/fictitious/non-equilibrium state (P<sub>2</sub>, V<sub>1</sub>; green dot). The irreversible work is then done under P<sub>2</sub> (P<sub>2</sub> < P<sub>1</sub>) ending in the final state (P<sub>2</sub>, V<sub>2</sub>; yellow dot). Work was done '''''by the system''''' hence has a negative value. | ||
| + | |||
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| + | [[File:PV_03_Irrev_IsoT_Comp.png|600px]] | ||
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| + | |||
| + | ::Starting at an initial state (P<sub>2</sub>, V<sub>2</sub>; green dot), when we add the weight quickly, but do not allow the system to change volume, we find ourselves in a temporary/fictitious/non-equilibrium state (P<sub>1</sub>, V<sub>2</sub>; pink dot). The irreversible work is then done under P<sub>1</sub> (P<sub>1</sub> > P<sub>2</sub>) ending in the final state (P<sub>1</sub>, V<sub>1</sub>; yellow dot). Work was done '''''on the system''''' hence has a positive value. | ||
| + | |||
| + | =====Reversible Work===== | ||
| + | Reversible work is a bit more straight forward. There are no fictitious/non-equilibrium states. The system moves between P<sub>i</sub> V<sub>i</sub> -->P<sub>f</sub> V<sub>f</sub> along the same path. | ||
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| + | [[File:Screen Shot 2020-09-07 at 8.31.16 AM.png|200px]] | ||
| + | :work is equal to the red area under the curve. | ||
| + | |||
| + | [[File:PV_04_Rev_IsoT_Exp.png|600px]] | ||
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| + | [[File:PV_04_Rev_IsoT_Comp.png|600px]] | ||
===Thursday, Sept 10, 2020=== | ===Thursday, Sept 10, 2020=== | ||
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::* Calibrate thermometer | ::* Calibrate thermometer | ||
::* Seal thermometer | ::* Seal thermometer | ||
| + | ::* [https://www.youtube.com/watch?v=gwswJSkS3Fg How Its Made: Thermometer] | ||
| + | ::* tour? | ||
| + | |||
| + | :- [[Media:HW_Indicator_work.docx|Indicator Diagram Worksheet]] | ||
===Friday, Sept 11, 2020=== | ===Friday, Sept 11, 2020=== | ||
| + | ====Sec 2.9: Comparing Work/Indicator Diagrams==== | ||
| + | continued... | ||
Latest revision as of 14:48, 14 September 2020
Monday, Sept 7, 2020
Review: The first Law of thermodynamics: ΔU = q + w
Sec 2.5: Reversible Work, continued
- Example Problem 2.1-like
Sec 2.6: Irreversible Work, continued
- Example Problem 2.2-like
Sec 2.7: Other Work
- focus on electrical work, Example Prob 2.3c
Sec 2.8: State Functions and Path Functions
READ
Wednesday, Sept 9, 2020
Sec 2.9: Comparing Work/Indicator Diagrams
Irreversible Work
The following shows a PV diagram, also known as an indicator diagram. The center figure is Fig. 2.7 in your text. The outside "cylinders" are my annotation to clarify the diagram. I have separated the "expansion" (irreversible, isothermal) work from the "compression" (irreversible isothermal) work.
- Starting at an initial state (P1, V1; red dot), when we remove the weight quickly, but do not allow the system to change volume, we find ourselves in a temporary/fictitious/non-equilibrium state (P2, V1; green dot). The irreversible work is then done under P2 (P2 < P1) ending in the final state (P2, V2; yellow dot). Work was done by the system hence has a negative value.
- Starting at an initial state (P2, V2; green dot), when we add the weight quickly, but do not allow the system to change volume, we find ourselves in a temporary/fictitious/non-equilibrium state (P1, V2; pink dot). The irreversible work is then done under P1 (P1 > P2) ending in the final state (P1, V1; yellow dot). Work was done on the system hence has a positive value.
Reversible Work
Reversible work is a bit more straight forward. There are no fictitious/non-equilibrium states. The system moves between Pi Vi -->Pf Vf along the same path.
- work is equal to the red area under the curve.
Thursday, Sept 10, 2020
- - Thermometer (cont.)
- Fill thermometer
- Calibrate thermometer
- Seal thermometer
- How Its Made: Thermometer
- tour?
Friday, Sept 11, 2020
Sec 2.9: Comparing Work/Indicator Diagrams
continued...