The equivalent conductivity of aqueous solutions of alkali metal salts of a number of ionic polysaccharides

Abstract Measurements of the equivalent conductivity of aqueous solutions of alkalimetal salts of a number of ionic polysaccharides at 25°C aie reported. The polysaccharides studied aie: (1) three carboxymethyleelluloses of various degrees of substitution (Li + , Na + , K + , Cs + salts) in the concentration range 4 × 10 −1 — 6× 10 −2 equivalents alkali ion per liter, (2) Polypec (Li + , Ni + , K + , Cs + Salts) in the range 1.5 × 10 −4 — 2 × 10 −2 equivalent alkali ion per liter, and (3) Dextransulfate (Li + , Na + , K + salts) in the range 3× 10 −4 — 10 −1 equivalent alkali ion per liter. The results are compared to some earlier data and to a limiting law for conductance of rod-like polyions derived by Manning. It is concluded that although qualitative agreement is obtained between observed data and the limiting law when various polyions of different charge densities are compared at a given concentration, the concentration dependence predicted by the limiting law is in agreement with the observed curves only for polyions of a relatively low charge density. At higher charge densities appreciable deviations occur, and dextlansulfate Which does not have the 10d-like polyion structure required by theory does not conform to the predicted concentration dependence at all.