Q. Consider a hypothetical system in which two aqueous solutions are separated by a semiper- meable membrane. Solution ? is prepared by dissolving 1.00 x 10-5 mol KCl in 10.0 g water.
Solution ? is prepared from 1.00 x 10-5 mol KCl and 1.00 x 10-6 mol of the potassium salt of a polyelectrolyte dissolved in 10.0 g water. All of solution ? is used to fill a dialysis bag, which is then sealed and placed in solution?.
Each polyelectrolyte ion has a charge of 10. The membrane of the dialysis bag is permeable to the water molecules and to the KC and Cl ions, but not to the polyelectrolyte. The system comes to equilibrium at 25.00 C. Assume that the volume of the dialysis bag remains constant.
Also make the drastic approximation that both solutions behave as ideal-dilute solutions.
(a) Find the equilibrium molality of each solute species in the two solution phases.
(b) Describe the amounts and directions of any macroscopic transfers of ions across the membrane that are required to establish the equilibrium state.
(c) Estimate the Donnan potential ?.
(d) Estimate the pressure difference across the membrane at equilibrium. (The density of liquid H O at 25.00 C is 0.997 gcm3.)