8.1 surface tension 1. 3 Theoretical definition of the surface tension W∝dA-oW=lA dw= odA is another kind of useful energy d=d7+++∑dhn For reversible process: B Sn=dG G At constant temperature and pressure T aA T dG=odA o is the excess energy per m possessed by the surface specific surface energy The energy of the surface increases Its unit is J m-2=NmI. which can be taken with the enlargement of the surface as the force exerted on unit length. surface area tension1. 3 Theoretical definition of the surface tension −W' dA −W' = dA For reversible process: , ' W dGT p − =  T p, G A     =       is the excess energy per m2 possessed by the surface. specific surface energy. Its unit is J m-2 = N m-1 , which can be taken as the force exerted on unit length. surface tension dG =dA The energy of the surface increases with the enlargement of the surface area. At constant temperature and pressure: -W = dA is another kind of useful energy. 8.1 surface tension B B B dG S T V p dA n = + + + - d d d   