A selectively permeable membrane separates two solutions. Water is able to pass through this membrane; however, sucrose (a disaccharide) and glucose (a monosaccharide) cannot pass. The membrane separates a 0.2-molar sucrose solution from a 0.2-molar glucose solution. With time, how will the solutions change?

• A. Water will enter the sucrose solution because the sucrose molecule is a disaccharide and, thus, larger than the monosaccharide glucose.
• B. Water will leave the sucrose solution because the sucrose molecule is a disaccharide and, thus, larger than the monosaccharide glucose.
• C. The sucrose solution is hypertonic and will gain water because the total mass of sucrose is greater than that of glucose.
• D. After the sucrose dissociates into two monosaccharides, water will move via osmosis to the side of the membrane that contains the dissociated sucrose.
• E. Nothing will happen because the two solutions are isotonic.

Answer: (E)

Verified step by step guidance

1. Understand the concept of osmosis: Osmosis is the movement of water across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.
2. Identify the solute concentrations: Both solutions have the same molarity (0.2 M), meaning they have the same concentration of solute particles.
3. Recognize the nature of the solutes: Sucrose is a disaccharide and glucose is a monosaccharide, but the size of the molecules does not affect the osmotic balance since neither can pass through the membrane.
4. Determine the tonicity: Since both solutions have the same concentration, they are isotonic relative to each other, meaning there is no net movement of water.
5. Conclude the effect on the solutions: Because the solutions are isotonic, there will be no change in the volume of either solution due to osmosis.