What is Adiabatic process: Definition and 119 Discussions
In thermodynamics, an adiabatic process (from the Greek adiábatos, meaning “impassable”) is a type of thermodynamic process which occurs without transferring heat or mass between the system and its surroundings. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work. It also conceptually supports the theory used to explain the first law of thermodynamics and is therefore a key thermodynamic concept.
Some chemical and physical processes occur too rapidly for energy to enter or leave the system as heat, allowing a convenient "adiabatic approximation". For example, the adiabatic flame temperature uses this approximation to calculate the upper limit of flame temperature by assuming combustion loses no heat to its surroundings.
In meteorology and oceanography, adiabatic cooling produces condensation of moisture or salinity, oversaturating the parcel. Therefore, the excess must be removed. There, the process becomes a pseudo-adiabatic process whereby the liquid water or salt that condenses is assumed to be removed upon formation by idealized instantaneous precipitation. The pseudoadiabatic process is only defined for expansion because a compressed parcel becomes warmer and remains undersaturated.
I was unable show that ##PV^k## must indeed equal some function of the entropy, ##g(S)##; maybe doing so would make things easier? I proceeded as below.
If we assume (as is almost surely intended by Callen) that in the given adiabatic (##d Q = 0##) process we are taking ##N## as constant and...
(picture of diagram below)So the task goes like this: gas is ideal. Process 3->1 s adiabatic and in process 1->2 work done is 1200J. Fill the table.
I don't know how to calculate work done in an adiabatic process because p2 and V2 are not given and I don't know gama(Cp/Cv).
I know that deltaU...
I have attached an image showing the perimeters of the problem.
I have included what I think is the solution, could someone please take a look and tell me if I am on the correct path, in the solution I am taking Joules as a common term to attempt to solve the question. The gas I have used is N...
Im confused on working backwards so to speak to find adiabatic work.
To find work for this adiabatic process, I either need to know the change in temperature OR the initial pressure (I think?).
The issue is that I don't know either the initial temperature nor the initial pressure so I am not...
I have been able to get everything except entropy. I know it's not zero. I know I have to find a reversible path to calculate it, but keep coming up with strange values so I don't think I'm doing it correctly.
can I do CpdT/T + CvdT/T = ds? I am having trouble calculating my P2 (I know my final...
in this textbook : http://www.fulviofrisone.com/attachments/article/486/Huang,%20Kerson%20-%201987%20-%20Statistical%20Mechanics%202Ed%20(Wiley)(T)(506S).pdf ;page 20
I don't understand about Eq 1.11 come to 1.12 ? I know
dU = U_V dT + U_T dV
dQ = dU + p dV
put dU into dQ. So dQ = U_V dT...
I'm not sure that this is an adiabatic process. As far as i can read, it is adiabatic if no HEAT or ENERGY is added. But pumping in molecules that are a non-zero temperature is an addition of energy, no?
Anyway - my solution with the assumption of an adiabatic process.
(skipping units for...
I tried this question and this the answer given in the book.
A cylinder is close at both ends and has insulating walls. It is divided into two compartments by a perfectly insulating partition that is perpendicular to the axis of the cylinder. Each compartment contains 1.00 mol of oxygen, which...
The actual data for the problem and my (and my friend's) attempt at a solution are in the attached file.
In a nutshell, this is what happened.
I obtained a solution based on the fact that the system is isolated. Thus the initially hot gas moves the partition doing work onto the initially cold...
The speed of sound in a gas at temperature T is given to be ## v=\sqrt{\frac{\gamma RT}{M}}##, where ##\gamma## is the adiabatic exponent, R is the gas constant and M is the molar mass of the gas. In deriving this expression, we assumed that the compression and expansion processes were so fast...
How is to possible to change the temperature without exchange of heat?
Could you please give me an example?
I know it is possible to keep the temperature constant while there is exchange of heat. This is possible when the heat supplied is consumed/lost to the surrounding.
But how is it...
Why is a thermally isolated process that occurs sufficiently slow is necessarily adiabatic and not just reversible process ? Here I mean that the definition of adiabatic process is no change in the entropy of the subsystem, and a reversible process is define by no change of the total entropy of...
*Here, no mention of these reservoirs being a gas, so I'm not sure if I can use the PV=nRT or the P*V^(gamma)=K equation.
SO I am left with only the 1st law.
If I can write dQ1( going out from object 1)= Cp (indep of T)*(Tf-T1)
dQ2(coming into the object 2)= Cp*(T2-Tf)...
Homework Statement
[/B]
An ideal gas is compressed to the same volume from the same initial state for both an adiabatic and an isothermal process. In which case will more work be done ?
2. Homework Equations
##dU=dQ - dW ##
##W=\int P\,dV ##(For isothermal)
##W=nc_vdT##...
Homework Statement
The change in entropy is zero for:
A. reversible adiabatic processes
B. reversible isothermal processes
C. reversible processes during which no work is done
D. reversible isobaric processes
E. all adiabatic processes
Homework Equations
## dS = \frac{dQ}{T} ##
The Attempt...
For an adiabatic process, Q = 0.
From the first law of thermodynamic,
ΔU = Q + W on the system
when Q = 0,
W = -PΔV,
then why is it that ΔU = Cv ΔT when Cv is meant for the constant volume? We know that when there is work done, the volume is changing, and making use of Cv sounds like an...
Hello.I have a question about entropy of a thermodynamic system.
1)If we have let say a gas that is separated by some thermo isolated walls (so no heat goes in or out) does the entropy of that gas conserve? I taught that if S=dQ/dt, because Q=0,then the entropy should be conserved.
2)So,does the...
Homework Statement
Calculate changes in A and G of one mole of an ideal gas that undergoes the following processes respectively.
1. adiabatic expansion from (T1, P1) to (T2, P2)
2. isobaric expansion from (P, V1, T1) to (P, V2, T2) (if it is not isothermal)
3. isochoric expansion from (V, P1...
Hello everyone!
I've been thinking a lot about this thermodynamics problem , hearing all sorts of opinions but never getting a full rigurous explanation. So we have a cylinder that is placed in vacuum. We insert in the cylinder a monoatomic ideal gas. The gas is trapped inside the cylinder with...
Homework Statement
[/B]
Find the final temperature, Q, ΔU, ΔH given the following
Initial state of gas
Ti = 353K
Pi = 250000Pa
2.5mols of gas
Cv = 12.47Jmol-1
Final pressure = 125000Pa
Homework Equations
PV = nRT
W = -PΔV
ΔH = ΔU + Δ(PV)
PVγ = constant
The Attempt at a Solution
Cv / R ≈3/2...
I have a question I hope someone may be able to answer.
I am currently working out an adiabatic compression process that gives me an initial pressure,volume, and temperature. Along with a final pressure and given that the cylinder/piston assembly does not conduct any heat. Another given is that...
A diabatic process is defined as follows:
Rapidly changing conditions prevent the system from adapting its configuration during the process, hence the spatial probability density remains unchanged. Typically there is no eigenstate of the final Hamiltonian with the same functional form as the...
Homework Statement
A turbine is driven by compressed air. The air enter the turbine with temperature ##T_1## and pressure ##P_1##. When the air leaves the turbine it's pressure is lowered to ##P_2##. Calculate the work done for one mol air.
The expansion of the air can be seen as reversible...
Homework Statement
Show that for a gas obeying the van der Waals equation ##\left(P+\frac{a}{v^2}\right)(v-b)=RT##, with ##c_v## a function of ##T## only, an equation for an adiabatic process is $$T(v-b)^{R/c_v}=constant$$
Homework Equations
##TdS=c_vdT+T\left(\frac{\partial P}{\partial...
Hi All,
I have a little query concerning the derivation of PV γ = constant. In my textbook of Physics, first they give the equation for adiabatic process using the first law of Thermodynamics, as;
dEint = W → (1)
where,
ΔEint ⇒ change in internal energy and W ⇒ workdone
Then, they used...
I find really confused about the adiabatic process. According to my textbook, adiabatic process is a process in which no heat is allowed to flow into or out of a system.
According to the first law of thermodynamics, change in internal energy=heat added to system- work done by system,so change...
I'm struggling to understand a concept which I assume is basic, but I can't seem to fit the pieces together. When speaking about an ideal gas, I understand that
ΔH = ΔU + Δ(PV) = ΔU + RΔT
So far so good. I also understand the relationship:
ΔU = Q + W... (W here is work being done on the...
I have a gas transitioning adiabatically between A (P1, V1) and B (P2, V2) where P1>P2 and V2>V1. The question is to determine the net work done on the gas if the gas is first expanded reversibly from A to B (w = dE = Cv(T2-T1)), and then compressed irreversibly from B to A (w = -Pext(V1-V2)) at...
Homework Statement
A well insulated container consists of two equal volumes separated by a partition - one half an ideal gas while the other is a vacuum. The partition is removed, and the gas expands. What is the entropy change per mole?
Homework Equations
dS = dQrev/T
S/R = Cp/R dT/T -...
Hello everyone, I still wonder if there's a change in entropy in adiabatic process. The definition of entropy is a quantity represents for the disorder state of a system. Arccording to kinetic theory of gas, temperature is for the state of chaotic motion of molecules. So I'm very confuse, can...
In conjunction with diving, a mixture of helium and oxygen called heliox. It will form the background to the following model invoice. Suppose that 1 mole of He and 1 mole of O2 is compressed as fast at half the volume that no heat exchange with the environment have time to take place...
Hello all!
I have a hard time about this one:
Think of an adiabatic process (can be either reversible or irreversible - doesn't matter). dQ = 0. Assume only, mechanical work is done on/by the system. So by 1st law of thermodynamics, dU =dW.
Now, everything is clear to me when I am dealing...
In class we're currently learning about reversible and irreversible adiabatic processes.
For reversible process, we got dq=0, so dU = dw = -P*dV = Cv*dT.
What I don't get is where did the Cv*dT come from?
I remember q=C*dT, but dq = 0 so I'm not sure what that means?
Also, where does Cv*dT...
I am going to report about Adiabatic process, specifically in cloud formation. Can someone help me some important points to consider?Im more concerned in cloud formation only since my topic is limited in that matter.
1. What is the science behind the adiabatic process in clouds?
2. Some...
Homework Statement
A gas of volume 1400[liter] and pressure 2.33[atm] expands in an adiabatic process to 2240[liter] and 1.2[atm]. plot the process on a V-P diagram.
I shorten the question, only this interests me. the number of moles is given.
Homework Equations
Equation of state: ##PV=nRT##...
Homework Statement
By how much does the temperature of an ideal monatomic gas change in an adiabatic process in which 4.0kJ of work are done on each mole of gas?
By how much does the temperature of an ideal diatomic gas (with molecular rotation but no vibration) change in an adiabatic process...
Homework Statement
As per attachment. Part iii
How would you do this question by integrating the work?
Homework Equations
W = - ∫P dV
PV^gamma = constant
The Attempt at a Solution
So I integrated the work with P= constant/ V^gamma and came up with this:
W = constant* (...
1) What is the reason why dH!=0 for an adiabatic(q=0) reversible process?
The mathematical argument is irrefutable and it is clear that it has to do with the process not being isobaric:
ΔH=ΔU+PΔV+VΔP , ΔU=work=−PΔV
Therefore, ΔH=VΔP and this is not 0.
However, I do not understand it...
No heat exchange is facilitated during an adiabatic process. Change is heat is zero.
How does this relates to the entropy being zero?
∫dQ/T?
But this could really just mean that the integral is of any constant.
Homework Statement
The problem involves a container holding a gas at high pressure. The container is opened to the environment, where the gas will cool down, producing a liquid or solid, and I want to find the work done by the gas throughout this process.
Homework Equations
PV^γ = constant
U...
One mole of an ideal monatomic gas initially at 298 k expands from 1.0 L to 10.0 L. Assume the expansion is irreversible, adiabatic, and no work is done. Calculate delta S of the gas and delta S of the surroundings.
I know that delta dS = dq/T but q = 0 in adiabatic processes right? So does dS...
Homework Statement
Hi can someone please have a look at this question and let me know if I am on the right track, thanks.
A diesel engine requires no spark plug; instead the air in the cylinder is compresses so highly the fuel ignites spontaneously on injection to the cylinder.
Q. If the air...
I have a small doubt regarding the workdone derivation in adiabatic process. Here is the derivation
W= (P1V1-P2V2)
= mR(T1-T2)/n-1
AS we know R/n-1 = Cv and Cp/Cv=1 also considering m=1
W=Cv(T1-T2)
but in textbook it is quoted as...