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Solutions A and B are separated by membrane permeable to K+ but not to Cl- . Solution A is 100mM KCl and solution B is 1mM KCl. Which of the following statements about solutions A and B is TRUE?

A. K+ ions will diffuse from solution A to solution B until the [K+] of both solutions is 50.5 mM.
B. K+ ions will diffuse from solution B to solution A until the [K+] of both solutions is 50.5 mM.
C. K+ will diffuse from solution A to solution B until a negative charge develops that opposes the movement of K+.
D. KCl will diffuse from solution A to solution B until the [KCl] of both solutions is 50.5 mM

User Joiggama
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1 Answer

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Final answer:

K+ ions will diffuse from Solution A with a higher concentration to Solution B with a lower concentration. This diffusion continues until a negative charge builds up that opposes further K+ ion movement, due to the Coulomb force. C. K+ will diffuse from solution A to solution B until a negative charge develops that opposes the movement of K+.

Step-by-step explanation:

The question addresses the process of diffusion across a membrane that is permeable to K+ ions (potassium ions) but not to Cl- ions (chloride ions). In the given scenario, Solution A contains a higher concentration of KCl (100mM) compared to Solution B (1mM). According to the principles of diffusion, particles move from areas of high concentration to areas of low concentration until a state of equilibrium is reached or until an opposing force, like the Coulomb force, prevents further movement.

In this case, the K+ ions will diffuse from Solution A (high concentration) to Solution B (low concentration). However, because the Cl- ions cannot pass through the membrane, a charge imbalance will develop. The accumulation of K+ ions in Solution B will lead to a build-up of positive charge, and the remaining Cl- ions in Solution A will lead to a negative charge. This separation of charge will eventually generate an electrical potential difference that opposes the further movement of K+ ions, according to the Coulomb force. The diffusion will stop once the electrical potential is sufficient to counterbalance the concentration gradient, not when the concentrations of K+ reach equilibrium.

Therefore, the correct statement about Solutions A and B is: C. K+ will diffuse from solution A to solution B until a negative charge develops that opposes the movement of K+.

User Sharron
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