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Thermodynamics

Thermodynamics. Thermodynamics is the study of the effects of work, heat and energy of a system. It is primarily concerned with the macroscopic(large scale) changes. All of thermodynamics can be expressed in terms of four quantities: Temperature (T) Internal Energy (U) Heat (Q) Entropy (S).

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Thermodynamics

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  1. Thermodynamics

  2. Thermodynamics is the study of the effects of work, heat and energy of a system. • It is primarily concerned with the macroscopic(large scale) changes.

  3. All of thermodynamics can be expressed in terms of four quantities: • Temperature (T) • Internal Energy (U) • Heat (Q) • Entropy (S)

  4. The “Zeroeth” Law of Thermodynamics states that if two systems are in thermal equilibrium with a third, then they are in thermal equilibrium with each other (same temperature).

  5. British Scientist CP Snow states the three laws humorously: • 1. You can’t win • 2. You can’t break even • 3. You can’t get out of the game

  6. energy is conserved for heat engines working in a cycle • Q = U - W, where Q is the net heat into the engine, U is the increase in internal energy, and W is the work done by the engine. 1. You can’t win.First Law of Thermodynamics

  7. Work= Pressure times the change in volume • W=PΔV or W=P(Vf-Vi) • Work is positive when gas expands • Work is negative when gas contracts

  8. Heat will not flow spontaneously from a cold reservoir to hot reservoir. • Nor, can an engine or combination of engines accomplish this alone. • No matter how efficient you are you will lose energy. • It is not possible to convert 100% of heat into work. • For an isolated system (and the Universe), the entropy of heat flow is to increase entropy. 2. You can’t break evenSecond Law of Thermo

  9.  When glucose is burned, heat is released, and the atoms become more disordered, showing increasing entropy. The fact that wood will burn but not spontaneously is an example of the second law of thermodynamics.

  10. Called Carnot efficiency, or the ideal efficiency of a heat engine • (Thot-Tcold)/Thot = Ideal efficiency • Temperatures must be in Kelvin. • Result is a percentage. Thermal Engine efficiency

  11. absolute zero cannot be reached. • But, experimenters try to get as close as possible – the record may be .000000700 Kelvin. • This is one reason we use the Kelvin scale. Not only does is the internal energy of a system proportional to the temperature, you never have to divide by 0 3. You can’t get out.Third Law of Thermo

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