7.1 Experiment: Rate of Diffusion of Solutes
In the initial set up of this experiment I had 2 sets of 3 screw-cap test tubes that had each been half-filled with 5% gelatin and 1-mL of the correct dye (either potassium dichromate, aniline blue, or Janus green) in each of the test tubes. I labeled the 3 test tubes of set 1 with which die they contained and marked them “5 ˚C”. Then with the other set I did the same exact thing, except I labeled these test tubes “Room Temperature”. I then placed set 1 of the test tubes in a 5˚ C refrigerator, while I kept set 2 at room temperature for a certain amount of time. I made sure to record the time I began the experiment in my lab manual. To begin, I removed set 1 from the refrigerator and compared the distance the dye had diffused in each of the 3 test tubes with the corresponding test tubes of set 2 that had been kept at room temperature. Next, I held each tube vertically in front of a white sheet of paper, and then used a metric meter to measure how far the dye had diffused from the gelatin’s surface (in millimeters). I then recorded each of these distances in my lab manual. I repeated this step for each of the test tubes in both set 1 and set 2 and recorded my results. Then, using my results, I calculated the rate of diffusion for each dye by using this formula: rate of diffusion = distance/ elapsed time (hours). Each of these calculations was then also recorded in my lab manual. I made sure I noted the time the experiment started, ended, and the total elapsed time in hours in my lab manual as well.
7.2 Experiment: Osmosis
I worked in a group of 4 to complete this experiment. First off I took the four sections of 15-cm long dialysis tubing that had been presoaked in dH2O and folded over one end of each tube (I found that twisting works well too) and tightly tied one of the 8 10-cm pieces of string (or waxed dental floss) that I cut with scissors around it to... [continues]
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