What is Isothermal: Definition and 227 Discussions

In thermodynamics, an isothermal process is a type of thermodynamic process in which the temperature of the system remains constant: ΔT = 0. This typically occurs when a system is in contact with an outside thermal reservoir, and the change in the system will occur slowly enough to allow the system to continue to adjust to the temperature of the reservoir through heat exchange (see quasi-equilibrium). In contrast, an adiabatic process is where a system exchanges no heat with its surroundings (Q = 0).
Simply, we can say that in isothermal process



{\displaystyle T={\text{constant}}}


{\displaystyle \Delta T=0}


{\displaystyle dT=0}

For ideal gases only, internal energy


{\displaystyle \Delta U=0}
while in adiabatic processes:


{\displaystyle Q=0.}

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  1. A

    B Change in entropy of reversible isothermal process

    So I had to find change in entropy of system in reversible isothermal process. $$T\Delta S_{sys.}=Q\implies \Delta S_{sys.}=nRln\left(\frac{V_2}{V_1}\right)$$ This was good because for isothermal process ##\Delta U=0\implies Q=W## Then I read this Throughout an entire reversible process, the...
  2. A

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  3. G

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  4. Ameen1985

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  5. Will26040

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  6. Chestermiller

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  7. jaumzaum

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  8. R

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  9. domingoleung

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  10. obstinatus

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  11. D

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  12. Sabra_a

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  13. D

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    I can get the P2 from P1V1=P2V2 --> P2 = 10Bar, but then how do i get the density? p=p/R*T ? where p=10Bar R=287J K-1kg and T 288K, density would be 12,1kg/m3? Is that right?
  14. Ignitia

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    Part (a) ΔS = ∫ (dq/T) because: dq = PdV = (nRT/V)dV Then: ΔS = ∫ (1/T)*(nRT/V)dV ΔS = nR ∫(1/V) dV ΔS =nR[ln(V2/V1)] Part (b) This is where I'm stuck. I know [P + a/(v/n)2][v/n - b] = RT can be solved for P and simplified to P = [RT/(v-b)]-[a/v2] since n=1mol But I don't know how to proceed...
  15. santimirandarp

    Isothermal expansion of a gas: heat of surroundings

    In an isothermal process, for an expanding gas ##\Delta U_{sys}=0## and ##Q=-W## but then, How can we evaluate ##Q_{surr} ##? It should be ##Q_{surr}=-Q_{sys}##, but I don't know how to show it in equations. If I try to get the result through the principles: ##\Delta U_{sys}=-\Delta U...
  16. Philip Koeck

    Can the isothermal expansion of an ideal gas be irreversible?

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  17. dRic2

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  18. M

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    I have become almost sure but have only some small doubts. Are all isothermal process actually ideal gas equation PV=mRT? If all such processes are occur in closed systems, this is so. Because it is isothermal the temperature is constant, R is constant and so is mass for a closed system. So the...
  19. shihab-kol

    Work done in adiabatic process vs work done in isothermal

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  20. M

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  21. M

    Why pressure decreases during isothermal expansion?

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  22. H

    Work done for isothermal process in terms of Helmholtz func

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  23. F

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  24. Pushoam

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  25. R

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  26. F

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  27. Z

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  28. TristanJones

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  29. L

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  30. O

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  31. M

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  32. M

    A How to Solve Isothermal Incompressible Navier-Stokes for Compressible Fluid?

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  33. P

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  34. Ian Baughman

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    What is wrong with this logic, if any? It does not seem like this should be true but maybe I'm mistaken. Assuming the process consists of two isobaric processes and two isothermal processes the work from B to C in terms of p1, p2, V1, and V2 is given by the following. 1) WBC=p2(VC-VB) 2)...
  35. R

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    is enthalpy change during isothermal process zero? if it is zero then what is the significance of enthalpies like enthalpy of vapourization or fussion since during phase transformation temperature remains constant.
  36. J

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  37. Ryaners

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  38. G

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  39. Geoffw

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  40. R

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  41. P

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  42. P

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  43. S

    Difference between Isothermal and Adiabatic?

    So for Isothermal, there is no change of T so hence delta U is 0. However, if there isn't a change of temperature, how is there a change of Q? I thought heat was the flow of energy of different temperatures. This confuses me for adiabatic as well. With no heat, how is there a temperature change...
  44. E

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  45. S

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  46. Thales Costa

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  47. S

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  48. M

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  49. A

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  50. S

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