Thermal equilibrium Definition and 103 Threads

Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium there are no net macroscopic flows of matter or of energy, either within a system or between systems.
In a system that is in its own state of internal thermodynamic equilibrium, no macroscopic change occurs.
Systems in mutual thermodynamic equilibrium are simultaneously in mutual thermal, mechanical, chemical, and radiative equilibria. Systems can be in one kind of mutual equilibrium, though not in others. In thermodynamic equilibrium, all kinds of equilibrium hold at once and indefinitely, until disturbed by a thermodynamic operation. In a macroscopic equilibrium, perfectly or almost perfectly balanced microscopic exchanges occur; this is the physical explanation of the notion of macroscopic equilibrium.
A thermodynamic system in a state of internal thermodynamic equilibrium has a spatially uniform temperature. Its intensive properties, other than temperature, may be driven to spatial inhomogeneity by an unchanging long-range force field imposed on it by its surroundings.
In systems that are at a state of non-equilibrium there are, by contrast, net flows of matter or energy. If such changes can be triggered to occur in a system in which they are not already occurring, the system is said to be in a meta-stable equilibrium.
Though not a widely named "law," it is an axiom of thermodynamics that there exist states of thermodynamic equilibrium. The second law of thermodynamics states that when a body of material starts from an equilibrium state, in which, portions of it are held at different states by more or less permeable or impermeable partitions, and a thermodynamic operation removes or makes the partitions more permeable and it is isolated, then it spontaneously reaches its own, new state of internal thermodynamic equilibrium, and this is accompanied by an increase in the sum of the entropies of the portions.

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  1. V

    B Heat exchange after thermal equilibrium

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  2. Dario56

    I Concept of Thermal Equilibrium in the Context of Canonical Ensemble

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  3. R

    I Estimating a thermal equilibrium on a custom made fridge

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  4. patrykh18

    Energy of a crystal in thermal equilibrium

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  5. P

    Thermal equilibrium in open systems

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  6. D

    What Is the Formula for Calculating Thermal Stabilization Time?

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  7. B

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  8. D

    Specific heat in the curve of equilibrium

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  9. haushofer

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  10. A

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  11. E

    I Planck formula and density of photons

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  12. G

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  13. T

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  14. RJLiberator

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  15. E

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  16. MexChemE

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  17. J

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  18. vetgirl1990

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  19. S

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  20. Coffee_

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  21. A

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  22. A

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  23. F

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  24. Shindo

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  25. nmsurobert

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  26. M

    Heat Capacity and Thermal Equilibrium

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  27. M

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  28. H

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  29. B

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  30. M

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  31. V

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  32. Feodalherren

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  33. M

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  34. M

    Does Temperature Affect the Time to Reach Thermal Equilibrium?

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  35. A

    Heat transfer and time needed to reach thermal equilibrium

    I was hoping someone could lend a hand with a question about thermodynamics. It's been years since I've done work on thermodynamics. Let's say I have a plastic 275 gallon liquid container, filled with a mixture of Propylene Glycol and Water (50/50 by volume). The container is placed inside of...
  36. W

    Why is the Fermi level a constant in thermal equilibrium?

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  37. M

    Is thermal equilibrium possible by the Law of Cooling?

    Law of cooling states that the rate of loss of heat by a body is directly proportional to the excess temperature of the body above that of its surroundings. The equation of determining temperature in time T(t)=Ta+(T0-Ta)*e^kt (Ta-ambient temperature, T0-initial temperature, k-heat transfer...
  38. 3

    Affleck-Dine and thermal equilibrium

    Hi, I am currently studying Cosmology on my own, and I am learning about the Affleck-Dine mechanism of baryogenesis. I understand that in this case the baryon asymmetry is generated by the decay of a supersymmetric flat direction carrying B, which is excited during inflation. Regarding...
  39. H

    Heat gained and lost by aluminium and water in thermal equilibrium

    Homework Statement A physicist pours 100g of water at 100'C into a 20g aluminium cup which already contains 50g of water at 20'C. The final equilibrium temperature of the water is 71.847. C(water)=4186J/kgC C(aluminium)=900J/kgC 1. the amount of heat lost by the hot water 2. the amount...
  40. O

    Heat loss and thermal equilibrium of underground aquifer

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  41. O

    Ideal gas-thermodynamics, thermal equilibrium

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  42. C

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  43. C

    Calculating Total Internal Energy of a System in Thermal Equilibrium

    Homework Statement Consider a system in thermal equilibrium consisting of N particles that have 2 energy states E1 and E2 separated by an energy ΔE. Given that $$N_1 = \frac{N}{exp(-ΔE/k_BT)},\,\,N_2 = \frac{N exp(-ΔE/k_BT)}{1+exp(-ΔE/k_BT)}$$ show that in the case of the lowest energy...
  44. S

    What is Maxwell Distribution, Thermal Equilibrium, Fluctuation and Wein's law?

    I was reading a book, 'Introducing Quantum Theory' by J.P.McEvoy, and I find it difficult to understand in details of Maxwell Distribution, Thermal Equilibrium, Fluctuation, Wein's law and Planck's quantum theory, so I am finding it difficult to follow Einstein's explanation of photoelectric...
  45. J

    A question about position of piston after achieving thermal equilibrium

    A vertical cylindrical container contains some helium gas that is in thermodynamic equilibrium with the surroundings. The gas is confined by a movable heavy piston. the piston is slowly elevated a distance H from its equilibrium position and then kept in the elevated position long enough for the...
  46. H

    Thermal Equilibrium between a Hot and Cold Body

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  47. C

    Highschool Question on Thermal Equilibrium

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  48. K

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  49. S

    Thermal equilibrium - Entropy driven

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  50. L

    Thermal Equilibrium - in a microwave?

    hi, i don't quite know how to pose this question but i'll try my best. if you have an object and heat one end of it, energy will move from an area of high energy, to an area of low energy. By this method, heat transfer will stop when all regions of the object are at the same temperature...
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