Biology Lab - Part C

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In part C of the experiment, we were to demonstrate osmosis between distilled water and each of the solutions in the dialysis tubes (water, 0.2 M, 0.6 M, 0.8 M, and 1.0 M sucrose all represented by unknown colors). We hypothesized that all of the dialysis bags except water will increase in mass. This is because the bags will be hypertonic to the distilled water solution in the beaker, meaning that there are more solutes and less water than the surrounding. In a hypertonic condition, water is rushed into the cell (or the dialysis tube in this case) in order to dilute the concentrated solution in the cell. Water would not change in mass because it is isotonic to its surrounding. By inserting these six dialysis bags filled with 25 mL of each solution into beakers of distilled water, we were able to see if there was the process of osmosis, if any. Before putting the six different dialysis bags into the solution of distilled water, we meticulously measured the mass of each bag. This was critical because we needed the initial mass in order to find the percent change in mass. After waiting for 30 minutes sharp, we measured the bags again and saw significant increases in mass for five out of the six dialysis bags. The orange solution did increase, but it was only a mere 1.47 percent change in mass. From this collected data, we were able to hypothesize which colored solution was which concentration. The order of the colors of solutions from least concentrated to most concentrated was: orange, green, yellow, blue, pink, and purple. How we were able to figure this out was because we knew that because of the solutions’ (except water) hypertonic nature, more water would rush in through the dialysis bags as the concentration increased. Not only did were we able to actually witness osmosis, we were also able to identify each colored solution to its concentration by

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