88.4 Surface adsorption of solution 8.4.2 Gibbs adsorption isotherm and the surface excess of solute per unit area Is O 00 rr\T Gibbs adsorption isotherm u2=u2+tINc The sign of T2 is determined by(ao/ac), RT while the value of l is determined by both(ao/ac)and cand the surface excess of solute per unit area is: 2 2 2   = + RT c ln 2 2 2 RT d dc c  = 2 2 2 T c RT c      = −     Gibbs adsorption isotherm The sign of 2 is determined by (/c), while the value of 2 is determined by both (/c) and c. 8.4.2 Gibbs adsorption isotherm 2 2 T       = −    §8.4 Surface adsorption of solution