The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. In the U-tube experiment illustrated above, which of the following statements correctly describes side B at equilibrium?
A) The concentration of NaCl and glucose will decrease, and the water level will increase.
B) The concentration of NaCl will increase, the concentration of glucose will decrease, and the water level will increase.
C) The concentration of NaCl will increase, the concentration of glucose will decrease, and the water level will decrease.
D) The concentration of NaCl and glucose will increase, and the water level will decrease.

Question

The solutions in the arms of a U-tube are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same.  In the U-tube experiment illustrated above, which of the following statements correctly describes side B at equilibrium?
A) The concentration of NaCl and glucose will decrease, and the water level will increase. 
B) The concentration of NaCl will increase, the concentration of glucose will decrease, and the water level will increase. 
C) The concentration of NaCl will increase, the concentration of glucose will decrease, and the water level will decrease. 
D) The concentration of NaCl and glucose will increase, and the water level will decrease.

Quizplus · Accepted Answer

At equilibrium, water will move from side A to side B due to the higher concentration of glucose in side B. As water moves from side A to side B, the volume of side B will increase and the water level in side B will rise. 
The selectively permeable membrane is permeable to NaCl, so NaCl will also move from side A to side B, resulting in an increase in the concentration of NaCl in side B. However, glucose cannot move across the membrane, so the concentration of glucose in side B will decrease as water moves in. 
Therefore, the concentration of NaCl will increase, the concentration of glucose will decrease, and the water level will increase in side B at equilibrium.

The Solutions in the Arms of a U-Tube Are Separated