Reversible process Definition and 44 Threads

In thermodynamics, a reversible process is a process whose direction can be reversed to return the system to its original state by inducing infinitesimal changes to some property of the system's surroundings. Throughout the entire reversible process, the system is in thermodynamic equilibrium with its surroundings. Having been reversed, it leaves no change in either the system or the surroundings. Since it would take an infinite amount of time for the reversible process to finish, perfectly reversible processes are impossible. However, if the system undergoing the changes responds much faster than the applied change, the deviation from reversibility may be negligible. In a reversible cycle, a cyclical reversible process, the system and its surroundings will be returned to their original states if one half cycle is followed by the other half cycle.

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  1. Z

    Chemistry How does it work to mix two gases reversibly in this device?

    Consider the problem of calculating the entropy change when we mix two ideal gases. Here is the setup The initial state consists of two ideal gases separated by a partition. We remove the partition and the gases diffuse into each other at constant temperature and pressure. This is an...
  2. 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...
  3. A

    Can energy truly be converted into matter in our world?

    Theoretically possible, only if the process is reversible. But is it really. My knowledge base is insufficient to answer that. I need help.
  4. aimLow

    I Reversible / Irreversible Fundamental Equation

    As far as I learned, the following statements should be correct (for closed systems, no chemical reactions), irrespective whether the process is reversible or irreversible (since S and V are state variables): dU=TdS−pdV dU=dQ+dW Does this imply, that the statement: dU≤TdS−pdV is wrong? This...
  5. mcas

    Find the change in entropy for an ideal gas undergoing a reversible process

    We know that $$dU=\delta Q + \delta W$$ $$dU = TdS - pdV$$ So from this: $$dS = \frac{1}{T}dU + \frac{1}{T}pdV \ (*)$$ For an ideal gas: $$dU = \frac{3}{2}nkdT$$ Plugging that into (*) and also from ##p=\frac{nRT}{V}## we get: $$S = \frac{3}{2}nk \int^{T_2}_{T_1} \frac{1}{T}dT +...
  6. cianfa72

    I Adiabatic irreversible process vs adiabatic reversible

    Hi, consider an adiabatic irreversible process carrying a thermodynamic system from initial state A to final state B: this process is accompanied by a positive change in system entropy (call it ##S_g##). Then consider a reversible process between the same initial and final system state. Such...
  7. Pushoam

    I Reversible Process: Why is it Important?

    Does this mean that in reversible process\ quasistatic process, the energy is not lost as heat and the process in which the energy is not lost as heat is known as reversible process\quasistatic process? I want to know why we want to have reversible \ quasistatic process.
  8. G

    I Is a quasi-static but irreversible process possible?

    Hello. I read the textbook of the thermodynamic and it said the definition of the reversible process as "thermodynamic process which is slow enough so the system state is always infinitesimally close to the thermodynamic equilibrium (quasi-static) during the process. Such a process can always...
  9. HethensEnd25

    An ideal gas closed system reversible process

    Homework Statement an Ideal gas at T = 70 C and 1 bar undergoes following reversible processes: a: Adiabatically compressed to 150 C b: then, cooled from 150 to 70 C at constant pressure c: finally, expanded isothermally to the original state (T=70 C and P = 1 bar) Homework Equations...
  10. S

    I Energy Level Change in Adiabatic Reversible Process

    Hello, I am currently trying to get my head around the concept of entropy. One way to understand it is that it can be related to the amount of available energy levels in a system. From what I read, the availability of energy levels in a system: 1) increase with an increase in the system...
  11. T

    Carnot Cycle with negative temperatures

    Homework Statement Heat engines at negative temperatures. Consider using two heat reservoirs to run an engine (analogous to the Carnot cycle of chapter 3), but specify that both temperatures, T_hot and T_cold, are negative temperatures. The engine is to run reversibly. (a) If the engine is to...
  12. E

    Entropy Change in a Reversible Process multiple phase change

    Homework Statement (a)How much heat must be added to a block of 0.120kg of frozen ammonia initially at 100oC to convert it to a gas at 80oC given the following information? (b) assuming this could be done using a reversible process what would be the total entropy change associated with this...
  13. S

    Is Dropping a Metal Block into a Lake a Reversible Process in Thermodynamics?

    Hello all. I have a quick question about entropy... I've just been formally introduced to it. Consider the example of a metal block of mass m and heat capacity Cp at temperature T1 = 60C being dropped into a large lake of temperature T2 = 10C. $$\Delta S_{block} =...
  14. S

    Entropy change in a reversible isothermal process

    Why does ∆S = 0 for a reversible process, but for a reversible isothermal process, ∆S is given by nRln(Vf/Vi) (or other variations of that equation)?
  15. A

    Calculating Reversible Work and Irreversibility in a Filling Container

    Homework Statement A rigid and evacuated container of volume V that is surrounded by atmosphere (P0, T0). At some point neck valve opens and atmospheric air gradually fills the container. The wall of container is thin enough so that eventually the trapped air and atm reach thermal equilibrium...
  16. L

    Why is the Definition of Entropy Restricted to a Reversible Process?

    Even though entropy is a state function and thus independent of path why is it that the definition of entropy is restricted to a reversible process? Eq 1: dS=dqrev/T First of all, is this for an open system, closed system or isolated system? The Clausius inequality deals with the exchange...
  17. A

    Thermodynamics - Carnot Cycle-esque question?

    Homework Statement A reversible heat engine produces work from the temperature difference that exists between a mass of m = 9 kg of an ideal gas (cv = 716 J/kgK, R = 287 J/kgK) in a rigid container and a heat reservoir at THR = 285 K. The only heat transfer interaction experienced by the...
  18. A

    Thermodynamics Problem - Adiabatic Reversible Process....

    Homework Statement A specific type of ideal gas has a specific heat capacity at constant pressure (cp=cv+R) that is a function of temperature T, such that cp=0.5+876T, where cp has units of J/kg/K and T has units of K. The gas, which is initially at T1 = 294 K and P1 = 1x105 Pa, undergoes a...
  19. P

    Thermodynamics. Irreversible and reversible Process

    When we were taught these in the class. There were a few terms I did not understand which my school teacher used. Firstly, they told us that the work in a reversible process occurs at the boundary of the system, an acceptable fact. All the energy is converted yo work done, and then showed us a...
  20. M

    Polish Physics Olympiad: Proving Adiabatic Reversible Process

    Homework Statement (56th Polish Olympiad in Physics, 2007) We have a tube of mass ##M##, consisting of two segments of diameters ##d_1, d_2##. The pistons (see the picture http://www.kgof.edu.pl/archiwum/56/of56-2-1-R.pdf) have mass ##m_1, m_2##. At the start the air inside had pressure...
  21. I

    Calculating the End Temperature of Adiabatic Compression for an Ideal Gas

    Homework Statement Air is compressed at room temperature from atmospheric pressure to ##\frac{1}{15}## of the initial volume. Calculate the temperature at the end of compression assuming the process is reversible and adiabatic.Homework Equations ##pV^\gamma = constant \Longleftrightarrow T...
  22. A

    Irreversible vs Reversible process

    I know that to calculate the entropy change in a process, I just need to calculate the entropy change in a process that has the initial and final states of the process and is reversible. I just don't understand what the actual difference between the irreversible versus the reversible process is...
  23. M

    Maximum work can be obtained from reversible process ?

    My book says 'Maximum work can be obtained only from thermodynamically reversible processes,' but why is it so? What is the cause? Actually to me the definition of reversible process is confusing. It says that at each step during the process, equilibrium is maintained. But, let's say,we have to...
  24. Useful nucleus

    Is every reversible process coincident with a quasi-static process?

    For a closed system: If we define a quasi-static locus (process) as an ordered and dense succession of equilibrium states in the thermodynamic configuration space. Then we define a reversible process as one in which no entropy is generated. Then it is clear that there are some quasi-static loci...
  25. O

    Curie temperature, reversible process

    Hello guys, first post in this forum :) Magnetism has always been complicated to understand for me, and I would like some help regarding Curie temperatures. We have just bought a new measurement equipment to out lab which shall be temperature calibrated with curiepoints. We have three...
  26. N

    Thermodynamics: Why must a reversible process be infenetesimally done?

    So my professor keeps bringing up that a reversible process must always be done infinitesimally slowly up. But why is that? I can't recall the explanation.
  27. R

    Showing work done on gas in a reversible process

    Homework Statement Ideal gas initially at temperature Ti, Pressure Pi, Volume Vi is compressed reversibly down to half its original volume. Temperature of gas is varied during the compression so that P = AV is always satisfied [where A is a constant] Show that the work done on the...
  28. G

    Change in I.E. for a reversible process

    Homework Statement A system absorbs QH = 481 J of heat reversibly from a hot reservoir at temperature TH = 370 K, and gives off QC = 155.4 J of heat to a cold reservoir at TC = 156 K. During this process, W = 90.9 J of work is done by the system. a) Find ΔIE, the change in internal energy...
  29. M

    A closed system containing a gas is to undergo a reversible process

    Homework Statement A closed system containing a gas is to undergo a reversible process from an intial specific volume of 2 ft^3/lbm and a intial pressure of 100 psia. The final pressure is 500 psia. Compute the work done per unit mass. a. Pv= constant b. pv^-2 = constantHomework Equations (1)...
  30. F

    Is electroweak symmetry breaking a reversible process?

    I can only assume it is, if a Higgs can be found anyway. I learned about hysteresis in certain physical processes. I don't have the math to guess nor Google skills to find a clear answer. If it were, would a sufficiently large and hot enough black hole be in danger of losing its mass terms...
  31. H

    Filling Flat Tire - Adiabatic Reversible Process

    Homework Statement A nearly flat bicycle tire becomes noticeably warmer after it has been pumped up. Approximate this process as a reversible adiabatic compression. Take the initial P and T of the air (before it is put into the tire) to be 1.00 bar and 298.0K. The final volume of air (after it...
  32. M

    Ideal Gas Under A (Complex) Reversible Process

    Homework Statement An ideal gas undergoes a reversible process 1-2-3-4-5. The stage from 1-2 as well as isobaric 2-3 and isochoric 4-5 stages are represented by linear segments. The Stage 2-3 is isothermal. The following relations are true: V_2=2*V_1 p_2=1.5*p_1 V_3=4*V_1 V_4=6*V_1...
  33. L

    Thermaldynamics problem, reversible process work done on

    Homework Statement One mole of a monatomic ideal gas is taken through a reversible process from an initial state "a" to a final state "b" during which the pressure of the gas varies with volume V as shown below. Calculate the work Won[/on](a->b) done on the gas during this process...
  34. S

    Definition of a reversible process

    I have seen a reversible process defined as one in which the system and surroundings are restored to their initial state without change elsewhere. As far as I am aware, the system and the surroundings completely occupy the universe. So, I am failing to understand what elsewhere means in this...
  35. S

    Thermodynamics 1st Law: reversible process for batteries?

    How could you ensure that an electric battery produced an electric current reversibly? How could you achieve maximum work from an electric battery? I really have no idea how to solve this. Thanks for your help! (Also sorry I first posted this in advanced physics...i don't know how to...
  36. E

    Is Entropy Change Different for Reversible Paths in Ideal Gas?

    Homework Statement An ideal gas is taken from an initial temperature Ti to a higher final temperature Tf along two different reversible paths: Path A is at constant pressure; Path B is at constant volume. The relation between the entropy changes of the gas for these paths is a) delta S(A) >...
  37. N

    Isentropic Process and Reversible Process

    Hi all, Will like to check if my below thoughts are right: 1) For a totally reversible process, it has to be both internally and externally reversible. And the definition of externally reversible means heat transfer between a system and reservoir where the temperature are the same. 2)...
  38. D

    Why must reversible process proceed slowly?

    Hi. I'm beginning to study thermodynamics. I'm told that an adiabatic process is a process that is thermally insulated and which is reversible. For instance if a piston is thermally insulated and we compress the gas inside, this compression (I'm told) has to be slow. But why must the...
  39. G

    Reversible Process: Final Temp Calc of Argon Mass 12.0g

    Homework Statement Calculate the final temperature of a sample of argon of mass 12.0 g that is expanded reversibly and adiabatically from 1.0 L at 273.15 K to 3.0 L. Homework Equations The Attempt at a Solution n = 12[g]/40[g][mol]-1 = 0.3 [mol] pVi=nRTi p =...
  40. A

    Maximum work during reversible process?

    maximum work during reversible process? I have seen maximum work is achievable when the process is carried out reversibly. Is it correct? For example, if you look at the following problems, 1) Ten litres of an ideal gas at a pressure of 10 atm expands isothermally against a constant...
  41. D

    When is the Heating of a Pot of Water Reversible?

    Homework Statement A pot is half filled with water and concealed by a lid so that no vapor can escape. The pot is then heated on a stove so steam is formed inside the pot. Now the heat is turned off and the vapor condenses into water. Explain when the process is reversible/irreversible. The...
  42. A

    Thermodynamics: reversible process, equilibrium and entropy

    Hi, everyone. i have several questions about thermodynamics which I just read. 1. Why does a reversible process require equilibrium of the system all the time? 2. Is every process reversible if it's very very slow so that the system is in equilibrium all the time( and there's no friction...
  43. J

    Cyclic Machine: Reversible Process?

    A cyclic machine receives 325 kJ from a 1000 K energy reservoir. It rejects 125 kJ to a 400 K energy reservoir, the cycle produces 200 kJ of work as output. Is this cycle reversible, irrerversible, or impossible? Not exactly sure what he is looking for here. But, since W=QH-QL, does that mean...
  44. K

    Change in entropy in irreversible and reversible process

    It is stated that the change in entropy of an isolated system during an irreversible process is > 0; while for a reversible process, it is = 0. An isochoric process has a change in entropy given by : nCv(Pf/Pi). Does this mean that it is an irreversible process? ARen't isochoric processes...
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