8.11.4 Donnan Effect of macromolecular solutions 4.2 Donnan Effect polyelectrolytes 藏NaP NaCl NaP H,O polyelectrolyte Semipermeable membrane (unaCd,=(uNaI(Na'I[cr]=(Na] Nap->Na+p (+x)x=(b-x)b-x) 丌=2cRT 2c+2c6 Rt C+26 C+26 Na p zNa tp Two limiting cases. b<<c TT=2CRT 丌=(z+1cRT 1b>>c丌=cRT1 It's hard to determine molar mass of a When a very large amount of Nacl is present, polyelectrol te the donna effect can be completely eliminatedNaP H2O c + − NaP ⎯→Na + P polyelectrolyte  = 2cRT Semipermeable membrane It’s hard to determine molar mass of a polyelectrolyte. + − ⎯→ + z Naz P zNa P  =（z +1）cRT NaCl b NaP c ( ) ( ) NaCl L NaCl R  =  ( ) ( ) L R [Na ][Cl ] [Na ][Cl ] + − + − = (c + x)x = (b − x)(b − x) c b b x 2 2 + = RT c b c cb         + + = 2 2 2 2  Two limiting cases: b<<c b>>c  = 2cRT  = cRT When a very large amount of NaCl is present, the Donna effect can be completely eliminated. 8.11. 4 Donnan Effect of macromolecular solutions 4.2 Donnan Effect polyelectrolytes