where and is the area of interface. RHS of the above equation is independent of the surface property hence is independent of choice of surface. There is no uncertainty in this RHS since, being bulk properties, all are known measurables. Thus, if the interface is chosen in such a way that (Gibb’s convention) we have,
and 
is the area of interface. RHS of the above equation is independent of the surface property hence 
is independent of choice of surface. There is no uncertainty in this RHS since, being bulk properties, all are known measurables. Thus, if the interface is chosen in such a way that 
(Gibb’s convention) we have, 
