All Questions
Tagged with reversibility thermodynamics
535 questions
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How to know when a reversible process between end states exists?
I am continuing to try to understand maximum work reversible processes (and a subset thereof -- Carnot cycles) better. I am here curious about the following system.
(1) Consider one mole of a gas (...
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Callen's Maximum Work Theorem: why doesn't heat lost equal heat absorbed (and likewise for work)?
This question was, effectively, asked here (please refer to that question for additional context); however, I don't think the given answer is correct (or at least complete) despite my having added a ...
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Why is any real process which proceeds through non-equilibrium states necessarily irreversible?
As per the title, why is any real process which proceeds through nonequilibrium states necessarily irreversible?
The question came up when reading Callen's definition of "reversible process" ...
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Reversibility and its surroundings
I was thinking about the definition of reversibility but there is something that I cannot understand. In real life the surrounding of a system (anything else in the universe) is always changing making ...
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Is there an equivalent of "adiabatic" for work (i.e. a workless transformation)?
In Fermi's Thermodynamics (1937), Chapter I, §1, he defines an isochore transformation as
a transformation during which the system performs no external work
He then discusses the case where the ...
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Question about "the nature of the gas" (TD transfomations)
$n = 1$ mol of a perfect gas pass from an initial state $A$ to a state $B$ though an isothermal transformation where $T_A = 300 $K and $V_B = 2V_A$.
Then from $B$ to $C$ though an isochoric ...
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2
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When is a thermodynamic system isobaric?
I came across a problem where a piston and gas arrangement was present and it was heated, so if the piston is free to move we call it isobaric. But is it only true if it is quasi static (reversible ...
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Please explain why the Carnot cycle is reversible while the Otto cycle is irreversible using the kelvin or clausius statement of the second law [closed]
why is the Carnot cycle reversible while the Otto cycle irreversible according to Kelvin-planck statement
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Difference between spontaneous and irreversible process?
I am confused about the difference between a spontaneous process and an irreversible process. Based on what I read so far, both processes increase universe's entropy. I never heard of any reversible ...
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What does $Q$ refer to in this inequality $\Delta S\ge\frac{Q}{T}$?
Entropy change of a system due to heat $Q$ can be expressed by the following inequality (assuming that temperature is constant):
$$\Delta S_\mathrm{sys}\ge\frac{Q}{T} \tag{1}$$
It can be expressed ...
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How it is possible for entropy of universe to increase during reversible process?
To calculate the entropy change of the universe when a closed system undergoes an irreversible process, one must choose a reversible process and calculate the following integral
$$\Delta S=\int \frac{\...
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Enthalpy in a non-reversible isobaric process
I know that in a reversible isobaric process, the enthalpy change of the system is the change in heat for that system. What happens if the process is not reversible? I.e only the outside pressure is ...
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Derive $ΔS = Nk\ln(V/V_0)$ using fundamental equations of thermodynamics [closed]
I am considering a system with an ideal gas undergoing an adiabatic expansion. The initial volume is $V_0$ and final is $V$.
From this, How do I derive $\Delta S = Nk\ln(V/V_0)$ using fundamental ...
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Entropy change in heated block [closed]
The header of the problem asks us to calculate the entropy change $\Delta S$ (in the universe) when heating an iron block from $T_1$ to $T_2$, knowing its heat capacity $C_V$. Is it possible to ...
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Are work and heat state variables (or functions) for reversible processes?
I was reading the second edition of "THERMODYNAMICS AND AN INTRODUCTION TO THERMOSTATICS" by (late) Herbert B. Callen which states
(Furthermore) the delivery of work (and of heat) is ...
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How can an irreversible isothermal process exist?
An isothermal process is one in which temperature of the gas is constant throughout the process.
From my physics textbook:
the state of a gas is described by specifying its pressure $p$, volume $V$ ...
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Example of an irreversible process using this formal definition
Some time ago, I asked for a definition of thermodynamic reversibility without mentioning entropy, and a user came up with the following formal definition of a reversible process:
Definition:
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2
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Does the rate of heat addition to a thermodynamic system affect its final state?
I have read that the entropy change of a system is greater than or equal to the integral of the heat added to it divided by its temperature. The case where entropy is equal to the integral is when the ...
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Can reversible computers really perform truly reversible computations in practice? [closed]
Someone once told me that with reversible computers there is no energy cost for the computation itself, there is only a cost for running the hardware. But is this true in practice, or is it only an ...
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Free energy change in reversible/irreversible processes
Yet another follow up to this question,
I am struggling to understand the example provided in Chet Miller's answer:
An example of this is expansion of an ideal gas in contact with an ideal constant ...
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Difference between Reversible and Irreversible processes in Physics vs. Chemistry
In Physics a reversible process is defined as one in which the system can be returned to its initial conditions via the same path (along the PV Diagram), and every point along the path is an ...
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Can someone explain this to me? About reversible computing with finite energy and thermal equilibrium
In Life, The Universe, and Nothing: Life and Death in an Ever-Expanding Universe, they examine the implications of dark energy on the ultimate fate of life.
Then they say this,
It was long thought ...
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$dq_{rev}$ and $dq$, which one is larger? [closed]
Im learning about entropy and some concepts makes me confusing.
For a reversible and irreversible process with a same initial state and final state, it is said that entropy change of a system is ...
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316
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Why the third law of thermodynamics requires reversibility?
A possible expression of the third law of thermodynamics is that, it is impossible to reach absolute zero in a finite number of reversible transformations.
I'don't understand why the transformations ...
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Reversible thermodynamics processes
A problem asks me to find the entropy increment in the machine operating some thermodynamic cycle. Can I assume that any closed cycle can (theoretically) be obtained by using two reservoirs at some ...
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A reversible transformation, but there is finite temperature heat transfer?
Suppose to have 3 heat reservoirs, the first at temperature $T_1$, the second at temperature $T_1+dT$ and the third at temperature $T_2>T_1$
Then, consider a system, which volume is constant, in ...
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422
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What are the properties of reversible and irreversible thermodynamic processes?
why do we say that reversible processes are slow whereas irreversible processes are fast?
Rusting is irreversible yet slow
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Why can't a heat engine have 100% efficiency?
Using the idea of isotherms and adiabats, I came up with the following argument to convince myself. First imagine the working gas within the system being heated along an isochore (hence all heat ...
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Work done in an isolated system
Question: An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If $T$ is the initial temperature and $T^\prime$ is the final temperature then compare the final ...
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How can the Entropy (change in entropy) of reversible and irreversible process be the same? If Entropy of reversible process is 0
E.g., the change in entropy of a reversible process 0, then irreversible process should have 0 change in entropy. This question arose because I couldn't understand why generally work done by ...
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Reversible/Irreversible Fundamental Equation [duplicate]
I do have some problems in understanding how the fundamental equation may be written correctly.
For a closed system without chemical reactions (and compression work being the only form of work done), ...
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What is Entropy Balance Relative to (un)Compensated Heat of Clausius?
Consider the ideal Carnot cycle consisting of two ideal reversible isothermal stages at $T_0$ and $T_1$ and two ideal adiabatic reversible (isentropic) stages connecting them; assume that $T_0 > ...
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Why is the final temperature of irreversible adiabatic processes higher than that of reversible adiabatic processes?
Suppose an irreversible adiabatic expansion process and a reversible adiabatic expansion process are starting from the same initial state, say, P1V1. Now, let both of these processes have equal ...
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Are there any time irreversible processes on earth which aren't due to the sun?
The sun is very hot. The earth is cold. Energy always flows from hot to cold systems. Due to the temperature difference, useful energy can be imparted onto earth (i.e., blackbody radiation from the ...
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How do I prove reversible transformations are necessarily quasistatic without using entropy?
I have the following definitions:
A transformation is said to be quasistatic if it passes only through equilibrium states (that is, the thermodynamical coordinates of the system are defined at every ...
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How can we say that work done by carnot engine in a cycle equals net heat released into it even when it is operated b/w 2 bodies and not 2 reservoir?
When a carnot engine is operated between 2 reservoir then after each cycle it return to its initial state so change in internal energy is zero and so work done by it equals net heat released into it. ...
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How does a reversible Carnot cycle transform heat to work?
To make clearer what I am asking let me introduce a new terminology to avoid any misunderstandings. Let the heat flow, which is rate, between a reservoir and an engine be denoted by $\mathfrak J$ and ...
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Understanding page 141 of Blundell’s Concepts in thermal physics
On this page (in the second edition), there is a figure containing two states A and B of a system:
There are two paths between A and B: one is an irreversible change, and the other is a reversible ...
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Why isn't the free expansion of a gas in an adiabatic container isentropic?
If you expand a gas adiabatically using a piston, the process is isentropic. However, if you simply remove the piston and let the gas expand freely, the process is now not isentropic. What makes these ...
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Proof of Caratheodory's theorem
Caratheodory's formulation of second law of thermodynamics, also referred to as Caratheodory's principle states
In any neighbourhood of any thermodynamic state $P$ there exist states which are ...
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Understanding the use of $d$ and $\partial$ in thermodynamics
It seems a hundred variations of this question have been asked, and it's difficult to find which of those questions relates to exactly what I'm asking. My apologies if exactly this question has ...
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Defining reversibility without resorting to entropy
Is it possible to define the concept of reversible process without using any mention to entropy?
The Wikipedia definition of reversible process seems to accomplish this by stating that:
In ...
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Fundaments of thermodynamics and separating entropy
I tried to write down my "own" fundamental rules of thermodynamics, which I can then use as solid ground to understand the rest of the topic. The main thing I thought of is separating ...
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Questions about Maxwell's demon
I've been reading about Maxwell's demon and the current accepted solution for it (deleting information results in an increase in entropy), but there are two things I don't understand about the ...
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What are the requirements to apply the Laplace Law in Thermodynamics ? Reversible and adiabatic, or just adiabatic?
The Laplace's Law in thermodynamics states that an adabatic reversible transformation of a perfect gas verifies the following identity :
$$
PV^{\gamma} = cte \qquad \left( \gamma = \frac{C_p}{C_v} \...
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Can heat(?) flow from a cold object to hot object?
When we dip a spoon (stainless steel) into ice cream, does it becomes cold or stay the same temperature? If it does, can we say that heat(?) can flow from cold to hot objects?
Is this the reason ...
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Do irreversible thermodynamic processes CONSTITUTE time or do they MOVE IN time? [closed]
Time can be associated with irreversibility. A broken egg can't reassemble. Most, if not all, processes are irreversible and this is associated with time going in one direction. Ŕemarkably, living ...
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Entropy of a deterministic reversible system
Suppose a deterministic reversible system evolving from state A of gas located in a small bottle in an otherwise empty room, to state B where the gas is dispersed throughout the room.
Why is the ...
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Why is rapid expansion/compression reversible?
I am looking over the Otto Cycle on this MIT website and it says at one point "the processes from 1 to 2 and from 3 to 4 are isentropic" in reference to the expansion and compression of the ...
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Why is rapid expansion/compression considered a reversible/isentropic process?
I am looking over the Otto Cycle on this MIT website and it says at one point "the processes from 1 to 2 and from 3 to 4 are isentropic" in reference to the expansion and compression of the ...
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