What is Reversible process: Definition and 43 Discussions
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.
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...
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...
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 +...
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...
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.
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...
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...
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...
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...
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...
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} =...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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.
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...
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...
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)...
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...
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...
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...
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...
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...
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...
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) >...
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)...
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...
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 =...
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...
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...
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...
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...
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...