PChem312 f20 w4
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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...