The Effect of Concentration Gradient on Osmosis
Osmosis is the passive movement of water from an area of higher concentration to an area of lower concentration, usually across a membrane (Thorpe 2013). Tonicity is the ability of a solution surrounding a cell to gain or lose water (Reece 2011). There are many factors that affect the rate of osmosis. These include temperature, surface area, difference in water potential, pressure, light and dark and most importantly what we will be talking about today the concentration gradient. It is said that the movement of osmosis is affected by the concentration gradient; the lower the concentration of the solute within a solvent, the faster osmosis will occur in the solvent (APEC 2013). I believe that this is very true and through the evidence I obtained by doing the following experiment, I have proved that the lower the concentration of the solute, the faster that osmosis will happen in the solvent.
To start we grabbed 5 strips of dialysis tubing, 10 orange clamps, and beakers labeled 1 through 5. After we got those supplies we soaked the dialysis tubing until it softened. We then clamped on end of each dialysis tube. After this was done we filled each dialysis tube with 10 mL of a specific concentration of liquid and then clamped the other end. One with tap water, one with 20% sucrose, one with 40% sucrose, one with 60% sucrose and another with tap water. We then filled up the beakers with the liquid required, just enough so that it would cover the dialysis tubes when put in there. Beakers 1 through 4 were filled with tap water, while beaker 5 was filled with 40% sucrose. After both the beakers and the tubes were full we gently blotted the filled tubes to remove any access water. Then we weighed each tube to get the start weight. After that we put the tubes in each of their respected beaker: tap water in tap water, 20% sucrose in tap water, 40% sucrose in tap water, 60% sucrose in tap water and finally the 2and tube of tap water into 40% sucrose. We then took them out and weighed them every 10 minutes and recorded them in the first chart. We went for 60 minutes. After we filled out our first chart which was simply the bag weights, we stated on the second charts which was the cumulative change in weight (g). To find these numbers we subtracted the weight of the tube at time = 0 from the weight of the tube at the time measured. After we completed this table we had one more to do. The last table we did was the corrected cumulative change in weight (g). To find these numbers we subtracted the change in weight of tube one from the change in weight of the tube at the time measured. These are the numbers that we graphed.
The results came out just as expected. The tube that contained the greatest concentration of the sucrose, the 60% sucrose, absorbed much more water a lot faster. This means that osmosis occurred faster in the tube that had the higher concentration gradient. We see this with every tube. 60% being the highest concentration, gained weight the fastest, 40 % the second fastest, 20% being the slowest. We also see the results in the tap wter in 60% sucrose. The weight went down dramatically because the liquids were reversed. Table 1:
Bag Weights (g)
Cumulative Change In Weight (g)
Corrected Cumulative Change In Weight...
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