) Before the assistant even begins to conduct the experiment, he needs to first make sure that he understands the procedures, and he has all of his materials prepared. He is going to need dialysis tubing bags for each solution to act as the semi-permeable membrane. He will also need a beaker with distilled water for each solution to be his controlled variable. He needs to put about the same volume of each solution into its dialysis tubing, making sure he has them labeled A, B, C, or D. The assistant then needs to calculate and record the mass for each of the bags. Each bag must then be placed into a beaker filled with distilled water and left there for several hours. He must make sure that each bag stays in the water for the same amount of time for accurate results. After the time has passed, the assistant needs to remove the bags from the beakers of water and record the new mass of the bags. The assistant then needs to use his recorded amounts to calculate the percent increase or decrease in the masses of the solutions. To do this he can use the formula, subtract his initial mass from his final mass, then divide by his initial mass, and multiply it all by 100.
B) The results of the experiment should be based on the change in mass in the different solutions. The solution with the greatest change in mass would be the 0.8 solution and the one with the least change should be the 0.2. The others would fall in order in between.
C) Diffusion is said to be, “the movement of molecules from a higher to lower concentration until equilibrium is achieved and the molecules are distributed equally.” In the experiment, the solution with 0.8 M of sucrose had a much higher concentration than the water in the beaker, so some of the sucrose moved across the semi- permeable membranes, which in this case were the dialysis tubes, and into the water by diffusion. Some of this happened in the other solutions as well just not as much because they had a smaller amount of sucrose in them. Diffusion by osmosis had the most to do with the change in mass. Osmosis is the diffusion of water molecules across a semi-permeable membrane from high to low concentration. In the solutions with greater amounts of sucrose, there was less concentration of water; therefore, more water traveled into the solution through the membrane because the water concentration was less inside. This is why the 0.8 M solution increased in mass the most, and the solution with only 0.2 increased the least amount. The processes of osmosis and diffusion could be used in this experiment to fix the mistake that the assistant had made.