Chemical Engineering - Chemical Engineering Thermodynamics - Discussion

dU = Q+W.

For T = K, dU = CvdT = 0.

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

Area under the PV diagram gives work. The area for isothermal process is greater than that for adiabatic and isentropic process.

Why not adiabatic?

Please explain me.

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.

What does second law of thermodynamics indicates ?

No, it is an adiabatic process where work obtainable is maximum.

According to given statement, the relation showed between volume and pressure not a temperature means T=constant, therefore it is ISO thermal Condition.

Can anyone explain it more clearly?

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.

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.