Question

what is difference between the reversible and
irreversible process in thermodynamics?

Answer 1

A reversable process is once in which things can go back and forth between its states. Irreversable is one in which once the reaction has occured, can no longer return to its previous state, due to loss of energy from the system or what not.

Answer 2

at what condition the process will be reversible!!!and in what case it will be irreversible

Answer 3

A theoretical or applicable example?

Answer 4

A reversible process is one in which the net entropy change is zero. In reality this is virtually impossible, as a system will always lose something by way of friction, deformation, sound, light, etc.

One of the more 'reversible' reactions that you can perform is the freezing of water. Without loss of energy from the system, it should take exactly the same amount of energy taken from the system to freeze it, to unfreeze it. Having a zero change in energy overall.

Answer 5

Because the nature of the way things are, you cannot fully isolate any system, so something will always be lost, so there will always be a net change in entropy.
An example is burning a piece of wood, it will release a lot of energy. Even in a closed system where you can capture all that energy, you can not shove it all back into the wood it was in, and reform the piece of wood.

Answer 6

but do our real engines are reversible or irreversible!!!

Answer 7

Everything we deal with in every day life will be irreversible. All due to entropy. Because you cannot have a totally isolated system outside of the theoretical.

Answer 8

ok ok i get it thank you

Answer 9

A reversible process is one in which the system is always at equilibrium as it is smoothly moved from one thermodynamic state to another. Making the process infinitely slow will make it reversible. In practice, given the speed of atomic-scale relaxation, it's often the case that even very fast processes by macroscopic standards (seconds) are essentially reversible.

It necessary to define reversible processes because derivatives of the fundamental quanties (like the entropy or energy) with respect to thermodynamic variables (like pressure and temperature) only have meaning for systems that remain always in equilibrium. This means, in particular, that certain formulas from thermodynamics you probably take for granted, like the amount of work for a small change in volume dV being equal to -p dV, or a small change in enthalpy being equal to T dS, et cetera, are only true for reversible processes.

In irreversible processes all bets are off, and thermodynamics provides you with no way to calculate things like work and heat, enthalpy and entropy change. You have to go to nonequilibrium theory, which is considerably less useful.