Question

∆S system for irreversible adiabatic compression is greater than zero
TRUE or FALSE ??
Please give me the correct explanation​

Answer 1

Explanation:

Now, I really didn't understand the point with this. First of all, I thought that ΔS>0 was the very definition of irreversible.

Second, if the process is adiabatic dQ=0 and so dS=dQ/T seems to be zero also. So there is something really wrong here.

I thought for some time on this now and couldn't get any conclusion.

Entropy change of a system has two causes: 1) Flux of entropy due to exchange of mass or heat with surroundings, ΔSflux, and 2) Entropy generated internally, ΔSgenerated. Total change in entropy of a system is therefore, ΔStotal=ΔSflux+ΔSgenerated. While ΔSflux can be either positive or negative, ΔSgenerated is strictly non-negative, i.e. ΔSgenerated≥0. In fact this may be taken as an alternative way of stating the second law (see: Modern Thermodynamics, by Kondepudi and Prigogine). ΔSgenerated≥0 has the status of a postulate, and cannot be proved (unless you get into statistical mechanics, where again a new postulate such as ergodic hypothesis is required).