Chemical Engineering - Chemical Engineering Thermodynamics - Discussion


Maximum work that could be secured by expanding the gas over a given pressure range is the __________ work.

[A]. isothermal
[B]. adiabatic
[C]. isentropic
[D]. none of these

Answer: Option A


No answer description available for this question.

Gajendra said: (May 25, 2013)  
It is the special fact of isothermal.

Sivareddy said: (Aug 13, 2013)  
I think that isentropic process will result maximum work for expansion process.

Thermoslayer said: (Aug 15, 2013)  
An isentropic process implies an adiabatic and reversible process. Reversible work will produce your highest yield of available work so the answer is C.

Pavan Krishna Reddy said: (Jan 12, 2014)  
Here, 1 point. Expanding of gas means volume is not const. The pressure is given, so we have a relation P inversely proportional to V. Pressure decreases therefore in this case temp didn't came into the picture because it is considered as constant variable. So the process is ISOTHERMAL.

Ramani said: (Feb 12, 2014)  
Here in this process temperature and pressure changes with respect to time. So process is isothermal.

Siva said: (Mar 1, 2014)  
Both adiabatic and isentropic are the same process then the alternate is isothermal.

Arvind said: (Apr 18, 2014)  
Temperature is constant pressure is vary inversely proportional to volume.

Blaise Paschal said: (May 12, 2014)  
Adiabatic lines on a PV diagram are always steeper than isothermal lines. This means that if we change the pressure by a specific amount the change is volume is always going to be more for an isothermal process then an adiabatic process.

Engr. Adeyemo, Festus said: (Aug 31, 2014)  
Boyle's law proves the answer is (A) ISOTHERMAL. For pressure to increase significantly and bringing about maximum work then absolute temperature must be held constant.

Under this Isothermal process we have Maximum Work Reversible,

i.e Wr = P1V1*ln (P2/P1).

Raj Musale said: (Oct 20, 2014)  
Consider a system possessing a piston-cylinder arrangement. Now are asked that; which process requires maximum heat (Q) to raise the piston.

So it is clear that if the piston-cylinder arrangement is considered as isothermal; then I have to provide maximum heat (Q) to the system. So the answer is (A).

Remington said: (Dec 23, 2014)  
dU = Q+W.

For T = K, dU = CvdT = 0.

-Q = W , hence heat input equals work output.

Shubham Tiwari said: (Sep 25, 2015)  
Area under the PV diagram gives work. The area for isothermal process is greater than that for adiabatic and isentropic process.

Milan Bhatt said: (May 7, 2016)  
Why not adiabatic?

Please explain me.

Sadam Shahani said: (May 21, 2016)  
In the first law of thermodynamics:

1. v is inversely proportional to pressure.
2. Expansion means increasing volume which means a decrease in pressure.
3. Pressure decreasing indicates that there is no change in temperature.
4. Increasing volume means Max work (w=Pv).

Hope this will be cleared. Thank you.

Hemant said: (Jun 14, 2016)  
What does second law of thermodynamics indicates ?

Debasish said: (Jul 10, 2016)  
No, it is an adiabatic process where work obtainable is maximum.

Anees Rehman said: (May 14, 2017)  
According to given statement, the relation showed between volume and pressure not a temperature means T=constant, therefore it is ISO thermal Condition.

Blessy said: (Aug 17, 2017)  
Can anyone explain it more clearly?

Ravi said: (Dec 12, 2017)  
Understand this problem is to see the P-V graph of Carnot cycle. Work done in any process will follow.

dW = p.dV.

It means if we plot a graph between pressure and volume of the gas then area covered under the curve followed by a process will show the work done.

Now, see the Carnot cycle and slopes of adiabatic and isothermal processes. There you can see that isothermal process will be covering more area than adiabatic process. And hence work done will be more in an isothermal process.

Amit Binwal said: (Jul 8, 2018)  
The PV graph of isothermal process cover max area as compare to adaibatic and isentropic process in expansion of gas that's why max work secured in isothermal process.

Hence option A is right.

Ashish Patel said: (Jul 31, 2018)  
Answer should be A.

As we know that, the here expansion process is occurring. And also it is a closed process. So from graph of P-V you can see the maximum area covered is by ISOTHERMAL LINE.

Anupam said: (Oct 4, 2018)  
The graph under the PV diagram for closed system gives the work. In the expansion region the graph of isotherm is above the graph of adiabatic curve, as the slope of adiabatic curve (gamma) is greater than that of isotherm curve. So the area under the isotherm is larger.

Manjit Gangwar said: (Oct 6, 2018)  
Only isothermal process exists in this question due to expansion process of a gas over a given pressure.

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