Question

A system undergoes a change from one state to another along two different pathways One being reversible and the other being irreversible. What can be said about the relative magnitudes of q reversible and q irreversible?

Please explain in detail.

Answer 1

reversible process :

reversible process is defined as " it is process in which the system remain in thermal equibrillium with its surrounding at every stage of process ,he system and its surroundings will be returned to their original states if one half cycle is followed by the other half cycle"

here, q = internal energy of system

Reversibility means the reaction operates continuously at equilibrium. In an ideal thermodynamically reversible process, the energy from work performed by or on the system would be maximized, and that from heat would be zero. so change in internal enrgy , Δq = 0 , because whenever one state start converting in to another.first we have to give some internal energy to the system. then process take place.when reversible process completed it released same amount of heat. because in reversible process there is no heat loss or any other losses.

so here Δ q = 0

irreversible process :

it it the process which not reversible process. in irreversible process , there is no thermal equibrillium at any stage of the system.in irreversible process we initially give some heat energy in term of internal energy of the system. but in irreversible system , there is heat loss occured. and there is no any equibrilliumm is established. so for that there is change in internal energy is occured.for irreversible system there is heat energy is converted in work and some amount of heat energy is loss due to system.

so for irreversible system, there is loss in internal energy occured.due to this Δ q is not equal to zero.it should be negetive or positive in magnitude