A dialysis bag is filled with distilled water and then placed in a sucrose solution?

The water level inside the dialysis bag will decrease as the sucrose molecules in the solution exert osmotic pressure, causing water molecules to move from the bag to the solution in an attempt to equalize the concentration on both sides of the membrane.

The movement of water molecules across a selectively permeable membrane is called osmosis. Osmosis occurs when there is a difference in the concentration of solute particles on either side of the membrane. Water molecules move from an area of low solute concentration (high water concentration) to an area of high solute concentration (low water concentration) in an attempt to equalize the concentration on both sides of the membrane.

In this case, the distilled water inside the dialysis bag has a lower solute concentration than the sucrose solution outside the bag. Therefore, water molecules will move from the dialysis bag to the sucrose solution by osmosis. This will cause the water level inside the dialysis bag to decrease.

The rate of osmosis depends on several factors, including the concentration gradient of solute particles, the temperature, and the permeability of the membrane. In this case, the concentration gradient is the difference in the concentration of sucrose molecules between the dialysis bag and the sucrose solution. The temperature is assumed to be constant. The permeability of the membrane to water molecules is also assumed to be constant.

Therefore, the rate of osmosis will be proportional to the concentration gradient of sucrose molecules. The greater the concentration gradient, the faster the water will move from the dialysis bag to the sucrose solution.