3·There is a water container separated by a semipermeable membrane in the middle
ID: 3475522 • Letter: 3
Question
3·There is a water container separated by a semipermeable membrane in the middle. KCl (40mM) has been dissolved in a half [Side I] of the container. Given that this membrane is permeable to K+ and Cl (a) What are concentrations of K+ and Cl- in the other half [Side II] of the container at the equilibrium? (b) If 10mM KA, a potassium salt, is added to Side I, what are concentrations of K+, C in both sides? Given that the membrane is non-permeable to ionized A-proteins. (c) What is this phenomenon called? Also define it with your own words. Answer:Explanation / Answer
Answer. (a) Movement of ions occur across semi permeable membrane till the concentration of ions equals on both side. So, at equillibrium the concentration of K+ ion at other side of the water container will be 40mM. Also the concentration of Cl- will be 40mM because both are monovalent ions.
(b) Since the KA solution is added to side 1, K+ions are higher at side one than the side 2 therefore, K+ ions will move from side 1 to side 2 according to the formula:
conc. of K+ = (conc.of K+ in side 1)2 divided by (conc.of K+ in side 2 + 2 x conc. of K+ in side 1)
conc. of K+ = (0.04)2/ (0.01 + 2 x 0.04)
= 0.0016 / (0.01 + .008)
= 0.0016/ 0.09
= 0.017
17mM of K+ on side 2 .
while the concentration of K+ on side 1 will be (0.04- 0.017) = 0.023 or 23mM.
Side 1 Side 2
K+ = 23mM K+ = 17mM
Cl- = 40-17mM = 23mM Cl- = 17mM
As the 'A' is not permeable so the concentartion of it will be same on side 10mM and will not present in side 2 (0mM).
Answer (c). This phenomenon is known as osmosis and the equillibrium is known as Donnan equillibrium.
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