87.5 Theories for strong electrolyte 1. The Debye-Huckel theory (1)Model hypothesis lonic atmosphere Radius: 1-100 nm Basic assumptions Peter J. w. Debye 1)Point charge Germany. Netherlands 2)Only Coulombic attraction 1884/03/24~1966/1102 3)Dielectric constant keep unchanged Studies on dipole moments and the 4) Boltzmann distribution, Poisson equation diffraction of X rays
1. The Debye-Hückel theory Ionic atmosphere Radius:1~100 nm Basic assumptions 1) Point charge 2) Only Coulombic attraction 3) Dielectric constant keep unchanged 4) Boltzmann distribution, Poisson equation Peter J. W. Debye + + + + + + + + + + + + − − − − − − − − − − − + − − (1) Model hypothesis Germany, Netherlands 1884/03/24~ 1966/11/02 Studies on dipole moments and the diffraction of X rays §7.5 Theories for strong electrolyte
87.5 Theories for strong electrolyte The Debye-Huckel theory Shielded Coulombic potential (2)Theoretical treatment e b/r 4丌EnEr tEC I b=/5h7) Debye lengt th 4NAle po) Inyi- RT BTe e kTb In y =-Az2 e 4I(EoE, kr)
Shielded Coulombic potential 0 4 j r Z e r = / 0 e 4 j b r r Z e r − = 1 2 0 2 A 0 4 r kT b N Ie = kTb Z e r i i 0 2 2 8 ln − = 1 1 3 2 2 A 0 2 1 2 0 ln 4 ( ) i i r e N Z I kT − = Debye length RT Wr i ' ln = − AZ I i i 2 ln = − + (2) Theoretical treatment 1. The Debye-Hückel theory §7.5 Theories for strong electrolyte