Work of expansion / compression or p – V work
a) Work done in irreversible isothermal expansion against a constant external pressure (pext)
V2 and V1 represent the final and initial volumes, respectively
b) Wore done in isothermal reversible expansion of nmoles of an ideal gas
(-ve sign has been used as it is work of expansion i.e. work done by the system)
c) Free Expansion (Expansion in vaccum)
Ideal gas : pext = O, w = O, ∆U = O, q = O
Real gas : pext = O, w = O
Work and heat are not state functions, they are path functions
