Monday, May 2, 2011

MIT Thermo... Studying for Quals... Notes and Video

Lots of cool stuff! This lecture has nice clean explanations of:
1. How a heat engine diagram is used
2. What adiabiatic means, (doesn’t exchange heat outside the system)
3. Why work examples are inexact, (they’re path dependent)
4. van der Waals equation of state




NOTES:

Adiabatic: No transfer of heat between the system and the outside world. Can be reversible and not.

Isobaric: constant pressure
Isothermal: constant temperature

triple point of water is used as a reference point for the Kelvin scale because it is the same everywhere.

Ideal gas law only holds for a very small range.

21:00 van der Waals equation of state


derivation of van der Waals, b is the volume consumed by the hard sphere molecules. a is the attractive force that slightly reduces pressure. a is divided by the molar volume squared because it is more likely to affect things in smaller volumes and less likely in larger volumes.




31:00 Convention in the definition of work. The environment compressing the gas is called positive work. Work done by the system on the environment is called negative.




The amount of work that you put in depends on the path to change the system. The state variables in the initial and final state do not care about the path.





45:00 heat engine first demonstrated
The differential of work used here is not an exact differential. The integral around a closed pat is not 0.
Heat flowing out of the system is called negative Q.
48:00 Adiabatic temperature change is the change of temperature without transfer of heat to or from the environment. Heat and work are really the same thing.

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