Final answer:
At equilibrium in a beaker with a membrane permeable only to Na+, Na+ ions would diffuse to balance their concentrations across the membrane, but the pH would remain unaffected as Na+ is inert and K+, Cl-, and HCO3- ions would not move across the membrane.
Step-by-step explanation:
The question pertains to a scenario where we have a beaker divided by a semipermeable membrane with ions on either side. Only Na+ is permeable through this membrane. At equilibrium, since Na+ is the only cation that can move, it will diffuse across the membrane from Side 2 to Side 1 until the chemical potential (concentration gradient) equilibrium is achieved. However, due to the selective permeability, there will be no net movement of Cl-, K+, or HCO3- ions. The Na+ movement will not affect the pH of the solution because it is inert, but if HCO3- were also permeable, its amphiprotic nature and its constants K2 and Ki would be important in determining the final pH. The fact that Na+/K+ ATPase pumps create an electrochemical gradient is significant in biological systems but does not directly affect the equilibrium state in this specific scenario because here we are not considering active transport mechanisms.