Five dialysis bags constructed from a semipermeable membrane

Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed. Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment? Which line in the graph represents the bag with the highest initial concentration of sucrose? Which line or lines in the graph represent(s) bags that contain a solution that is hypotonic at 50 minutes?

Solution

Answer:

1. Bag C contains a solution which is isotonic to 0.6 M sucrose solution in the beaker since it does not undergo a change in mass over time.

2. Bag A contained highest initial concentration of sucrose making it a hypertonic solution. So, water entered the bag through osmosis from higher concentration (in the beaker) to lower concentration (inside the bag), increasing its mass over time.

3. At 50 minutes, Bag D is hypotonic since it continues to loose mass (water) even after 50 minutes.

Bag E and A (as it appears from the graph) becomes isotonic to 0.6 M sucrose solution in the beaker, as no change in mass is observed after 50 minutes.

Bag B is still hypertonic and continues to gain water and increase in mass.