All Questions
26 questions
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Can ideal gas equation $PV = nRT$ be used in the intermediate stages of a irreversible and reversible process?
Suppose we have two processes, one is reversible and the other is irreversible. The ideal gas undergoes from state A to state B in both processes.
I want to know that can I apply the formula $PV = nRT$...
0
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3
answers
213
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Validity of the equation $dQ=CdT$ in different cases
I know this question may be too simple so I apologise for that but nonetheless very necessary. In my class we have defined the heat as $$\delta Q=CdT$$ with $C$ the heat capacity, but I'm unsure if it ...
- 69
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0
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49
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Can a fixed amount of ideal gas undergo a reversible process when 2 of either pressure, volume, or temperature are held constant?
I've seen some problems where this was the case: a fixed amount of ideal gas underwent a reversible process where temperature varied while pressure and volume were both held constant. How could that ...
- 39
0
votes
1
answer
20
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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 ...
- 383
1
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2
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2k
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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 ...
- 242
6
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5
answers
1k
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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 ...
- 3,638
0
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1
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625
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Does $PV=nRT$ hold for the endpoints of an irreversible process? [closed]
I have read the following:-
$PV=nRT$ holds throughout a reversible process
$PV=nRT$ does not hold throughout an irreversible process because the ideal gas law is only applicable for gases in ...
- 111
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1
answer
6k
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Is the enthalpy change in a reversible adiabatic expansion of an ideal gas 0?
I would like to know what happens to the enthalpy in a reversible adiabatic expansion for an ideal gas. Will it be greater than or equal to zero?
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2
answers
1k
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Is a constant pressure adiabatic irreversible expansion possible?
We know that adiabatic law for an ideal gas is,
$$ PV^{\gamma} =C$$
the differential of this under constant pressure is,
$$ P \gamma V^{\gamma-1} dV = 0$$
Now, the pressure and volume can't be at all ...
- 8,040
2
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2
answers
179
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Is it possible to deduce the second law of thermodynamics from the first?
Considering the First law of thermodynamics as an axiom dU=dQ-pdV for any infinitesimal process, we should be able to prove that for any reversible(quasistatic) and cyclic transformation, there is at ...
- 21
1
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2
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754
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Irreversible, Compression and expansion work for a piston with ideal gas
How can we calculate the work done by the piston or on the piston by including the internal pressure of the piston and not the external one. Because if the external pressure is doing work, the ...
0
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1
answer
318
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Work done by ideal gas under a reversible process which is not isobaric, isochoric, isothermal, adiabatic
First post, sorry for the poor formatting.
Question
Consider a non adiabatic system closed to mass exchange where an ideal gas traverses along a reversible path from state: to . What is the work ...
- 61
-1
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1
answer
578
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Maximum velocity of piston pushed by a gas on adiabatic irreversible expansion [closed]
I am currently studying for my country's IPhO selection process and thermodynamics has to be one of my favorites right now. However I came across a very odd problem that is making me revise a lot of ...
- 1,263
1
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2
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3k
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Example of reversible isochoric process for an ideal gas
I’ve seen many books considering reversible isochoric processes performed by an ideal gas. But is that possible?
Suppose I’ve a general isochoric process going from A to B, suppose I’m having a ...
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1
vote
1
answer
205
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Different ways to perform an adiabatic expansion
In this Wikipedia article https://en.wikipedia.org/wiki/Joule_expansion#Entropy_production, three ways to perform an adiabatic expansion are mentioned.
Irreversible non-quasistatic
Irreversible ...
- 1,510
0
votes
1
answer
478
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Gas behaviour - compression
I have read that the slow compression of a gas results in an increase in its temperature. Is it essential that the gas be compressed slowly? What happens if the gas is compresses quickly?
- 11
0
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1
answer
128
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Can we say higher entropy leads to better mixing in fluids?
We know irreversibilities always cause the entropy of the system to increase, but if we numerically find entropy generation due to heat transfer/fluid friction in a closed system, can we conclude ...
- 28
4
votes
2
answers
2k
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Are all reversible processes adiabatic?
My understanding is that in a reversible process there is no increase in entropy, it remains constant. So $\Delta S = 0$ no?
And since it's reversible we know from the second law that $\Delta S = \...
- 963
3
votes
4
answers
738
views
Does a reversible heat engine exchanging heat with an ideal gas that does a transformation imply that transformation is reversible?
Consider a reversible heat engine working between two sources. Suppose that one of the sources is a thermostat, while the other is an ideal gas which follows a transformation and exchanges some heat ...
- 2,637
1
vote
2
answers
260
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Free expansion of ideal gas, transient phase (3 questions)
We all know the classic scenario of free expansion. A contained gas expands into a vaccum and in the end we have $\Delta T = \Delta U = \Delta H = 0$ and $\Delta S = R \ln \frac{V_2}{V_1}$. This is ...
- 1,797
1
vote
2
answers
111
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Reversible expansion paradox
consider a mole of an ideal gas enclosed in a container with a mass-less piston undergoing isothermal reversible expansion. now we know that in an reversible process the system and the environment ...
- 319
1
vote
1
answer
595
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Sudden volume increase piston [duplicate]
I am wondering what happens in the following situation. I have a piston filled with an ideal gas for which I suddenly/instantaneaouly iscrease the volume. In particular I want to know what happens to ...
- 11
1
vote
0
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176
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Necessity of infinitesimal steps for reversible processes
Is there a mathematical proof for why a reversible process is one that has many infinitesimal equilibrium steps, rather than fewer large steps?
Maybe something along the lines of this?:
\begin{...
- 11
2
votes
1
answer
279
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Irreversible work
I'm having some trouble trying to find the irreversible work done by a perfect gas when expanding. I know that the reversible work is greater than the irreversible one, but how can I find the ...
- 357
0
votes
3
answers
554
views
Not Quasi-static, yet reversible process? Is this a valid example?
Imagine a gas (at room temp. and pressure) enclosed in a thermally insulating spherical container.
At some instant, the container instantly expands symmetrically (radially outward) to, say, twenty ...
22
votes
4
answers
3k
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How slow is a reversible adiabatic expansion of an ideal gas?
A truly reversible thermodynamic process needs to be infinitesimally displaced from equilibrium at all times and therefore takes infinite time to complete. However, if I execute the process slowly, I ...
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