Diffusion and Osmosis Free Essays

Diffusion And Osmosis Abstract In this Diffusion and Osmosis lab a total of three experiments were performed. For experiment 5. 1 we investigate diffusion through a selectively permeable membrane and the many factors that influence the rates of diffusion. We will write a custom essay sample on Diffusion and Osmosis or any similar topic only for you Order Now In experiment 5. 2 we investigate both animal and plant cells in different molar solutions and the different osmotic behaviors within the cells. In experiment 5. 3 we test the osmolarity of plant cells through the usage of potato tuber cells. In experiment 5. in order to observe diffusion we examine the Brownian movement by observing carmine on a wet mount slide, and by using dialysis tubing, we investigate the selective permeability to reducing sugar, glucose, starch, and iodine potassium iodine. In experiment 5. 2 we use samples of ox blood and Elodea plant to observe the net flow of water from the surrounding solution into the cells. In experiment 5. 3 in order to estimate the osmolarity of the potato tuber cells we use the methods of change in weight and change in volume. In experiment 5. 1 while observing the wet mount, the Brownian movement of the carmine particles are never ending and show no pattern. While investigating the permeability of the dialysis tubing through the Benedict’s test, the solution inside of the bag (glucose), was originally clear, but after the Benedict’s test turned a strong orange color, finally ending with a final color of dark blue-black. In experiment 5. 2 while observing the ox blood under the microscope the cells underwent either lysis or shriveled up. When observing the Elodea cells in distilled water and separately in salt water, the appearance and condition of the cell drastically changed. When the Elodea cell was placed into the distilled water, the cell became swollen and underwent lysis. However, when the Elodea cell was placed into salt water, the cell shriveled up and appeared bumpy. In experiment 5. 3 when placing the potato segments into different molarities of sucrose a trend appeared. With a higher sucrose molarity, the potato segment gained less and less weight until eventually, the potato lost weight. In experiment 5. 1, using this information we discovered from the wet mount, we concluded that smaller particles move more rapidly than larger particles. In the dialysis tubing experiment we determined from the color changes in and outside of the bag that iodine and glucose are smaller particles able to pass through the tubing, while the starch is unable to do so because of its larger particle size. Iodine was absorbed into the tubing, turning the solution into the resulting blue-black color. In experiment 5. we determined that when the animal cell is placed in a hypertonic solution, water left the cell making the cell shrivel up and appear bumpy, or crenate. However, when the animal cell is placed in a hypotonic solution, water enters the cell and undergoes lysis, making the cell swell and eventually burst. When observing the Elodea plant, we determined that the distilled water was the hypotonic solution and the salt water was the hypertonic solution and had a higher OAS. We determi ned that the preferred way of living for plant cells is in either an isotonic or hypotonic environment. In experiment 5. 3 we determined that as the sucrose molarity increases, less weight is gained by the potato, until eventually, the potato segments lose weight and their percent weight change becomes negative. Introduction In this lab, we observe the process of diffusion and osmosis. In the process of diffusion, molecules spread from an area of higher concentration to an area of lower concentration. When the molecules are even throughout the area, this is called equilibrium. Osmosis is the diffusion of water across a membrane. In osmosis water will move towards the higher concentration of solute. Diffusion and osmosis are both type of passive transport, meaning that no energy is required for the molecules to move into or out of the cell (Lewis, M. ). There are three types of solutions or environments in which cells can be submerged in: Isotonic, Hypertonic, and Hypotonic. In an isotonic solution, the concentrations inside and outside of the cell are both equal to each other. The net movement of water moves back and forth in equally, making the term â€Å"iso† meaning the same. In a hypertonic solution, the concentration outside of the cell is higher than that inside of the cell. This causes the water to exit the cell, making the cell shrivel up and shrink. If either animal or plant cells shrivel up and shrink, the cell may die. Finally, in a hypotonic solution, the concentration inside of the cell is higher than that on the outside. This causes the cell to gain water and grow larger. The difference is that plant cells may become enlarged, but are unable to burst due to the cell wall. Animal cells however are in danger of bursting, but the contractile vacuole will attempt to pump out the access water. Since substances move from a region of high concentration (more solute) to low concentration (less solute), remember that solutes will always move from a hypertonic solution to a hypotonic solution or solvents will always move from a hypotonic solution to a hypertonic solution. † (Wayne, R. ) During the experiments, diffusion and osmosis occur until dynamic equilibrium is reached. Plant cells will undergo the process of increased turgor pressure or plasmolysis, while animal cells may undergo crenation or lysis. Experiment 5. 1 Part A: I hypothesize that the movement of the single carmine particles, which are small, will have no given pattern and move more rapidly than that of larger particles. Experiment 5. 1 Part B: * I hypothesize that the I2KI will be absorbed into the tubing, changing the color of the solution inside the tubing. I also believe that the glucose will not move because the particles will be too large to bypass the dialysis tubing membrane. Experiment 5. 2 Part A: * I hypothesize that when the animal cell is in a hypertonic solution, water will leave the cell and cause it to undergo crenation. However, if the cell is in a hypotonic solution, water will enter the cell and the cell will undergo lysis and explode. Experiment 5. 2 Part B: * I hypothesize that when the Elodea plant cell is placed inside of the hypertonic salt solution the cell will shrivel up and may undergo plasmolysis. However, if the Elodea cell is placed in a hypotonic solution, it will result in an increased turgor pressure. Experiment 5. 3 * I hypothesize that the potato segment will gain weight when in a hypotonic solution. The potato segment should also lose weight while in a hypertonic solution. I believe that the higher the sucrose concentration, the more weight will be lost. These experiments are in order to determine the process of passive transport, osmosis and diffusion. The experiments will provide information and demonstration of molecules moving from an area of higher concentration to an area of lower concentration. We will learn how and why diffusion and osmosis happens in all living things. I predict that examining cells in hypotonic and hypertonic solutions will provide us with information about how cells react and how they return to their normal isotonic state. The methods of each experiment will allow us to see how animal cells undergo crenation and lysis, while plant cells undergo increased turgor pressure and plasmolyisis. Examining cells under the microscope will give us an in-depth look into how animal and plant cells react in hypotonic, hypertonic, and isotonic solutions. Enabling us to learn how dynamic equilibrium is reached through diffusion and osmosis. Materials and Methods In experiment 5. 1 the following materials are required in order to carry out the procedure: Part A: Dropper bottle of water, slide/cover slip, compound microscope, dissecting needle, and carmine powder. Part B: String, 500-mL beaker (1/3rd filled with water), handheld test tube holder, 3 standard test tubes, transfer pipettes, two 400-mL beakers to hold dialysis bag, 30-cm strip of moist dialysis tubing, wax pencil, 30% glucose solution, starch solution, Iodine potassium iodide solution, Benedict’s reagent, and a hot plate. In experiment 5. 2 the following materials are required in order to carry out the procedure: Part A: Test tube rack, three test tubes with screw caps (each containing one of three unknown solutions), dropper bottle of ox blood, newspaper or other printed paper, 4 clean microscope slides and cover slips. Part B: Compound microscope, 1 slide of Elodea in a hypertonic salt solution, 1 slide of Elodea in distilled water. In experiment 5. 3 the following materials are required in order to carry out the procedure: Part A: 1 potato, 1 large potato tuber, seven 250-mL beakers, marking pencil, forceps, balance weighing to the nearest 0. 01 gram, aluminum foil, petri dish, razor blade, cork borer, deionized water, paper towels, metric ruler, calculator, sucrose solutions (0. 1, 0. 2, 0. 3, 0. 4, 0. 5, 0. 6 molar) In experiment 5. 1 the dialysis tubing was filled with glucose and placed into a beaker of Iodine potassium iodide solution. The control of water was placed to the side until need for the Benedict’s test. After approximately thirty minutes the color of the glucose inside of the bag turned from clear to a dark blue-black color. While the iodine potassium iodide solution inside the beaker did not change color. After the Benedict’s test, the contents inside of the bag turned orange, while the solution inside the beaker turned to a lighter shade of orange. The control remained unchanged until after the Benedict’s test turned the solution a light shade of blue. In experiment 5. both the animal cells and plant cells were placed into hypertonic and hypotonic solutions. When the animal cell was placed into a hypertonic solution, the cell shriveled up and had a higher OAS. As the animal cell was placed into a hypotonic solution, the cell underwent lysis and eventually burst. The control was placing animal cells by themselves without any unknown solution. In experiment 5. 3, placing the potato segments into various sucrose molarities caused both weight gain and loss. The control was placing a segment of potato into a solution with a sucrose molarity of zero, and resulted in a 10% weight gain. The independent variable was the sucrose molarity, which ranged from 0. 0 to 0. 6 molar. The dependent variable was percent change in weight of the potato segments. In experiment 5. 1 part A: * Obtain all of the materials and prepare the wet mount by adding a single drop of water to a clean slide. * After adding the carmine to the slide by means of the dissecting needle, observe the slide under a compound microscope. * Begin by observing on low power, and then onto high power. * After your observations are complete, record the results and draw conclusions based on the results. In Experiment 5. 1 part B: * Prepare the dialysis bag by moistening the bag and adding 4 full pipettes of 30% glucose and 4 full pipettes of starch solution into the bag. * After sealing the bag, add 300-mL of water and several drops of iodine potassium iodide solution, until yellow, into a 500-mL beaker. * Record the color of the water and iodine potassium iodide in the data table. * After leaving the bag in the beaker for at least 30 minutes, remove the bag and record the color of both the inside the bag and inside the beaker. * Label three test tubes: control, bag, and beaker. Add 2 full pipettes of water into the control tube. * Add 2 full pipettes of the bag solution into the bag tube. * Add 2 full pipettes of the beaker solution into the beaker tube. * Add a single drop of Benedict’s reagent into each test tube. * Heat the test tubes in boiling water for three minutes and record your observations. In experiment 5. 2 part A: * Observe the three test tubes of unknown solutions and blood and record what you see. * Gather four clean slides and label them A, B, C, and D. * Place a drop of blood on slide D, and observe the shape of red blood cells without treatment. Place a drop of solution A onto slide A and add a small drop of blood to the edge of the cover slip. * Repeat with solution B and C with their respective slides. * Record your observations. In experiment 5. 2 part B: * Prepare the wet mount slide with the Elodea sample. * Observe the Elodea in both solution A and B. * Record what you see the cells do under the microscope into the provided data table. In experiment 5. 3: * Begin by cutting out seven cylinders of potato. * Record the initial weight of each piece and then transfer the potato pieces to the water beaker with the given sucrose molarity starting at 0. 0 and ending with 0. molar. * After incubating for 1. 5 to 2 hours, blotch the potato pieces with a paper towel and record their weight after being gently dried off. * Calculate the percentage change in weight by dividing (weight change/initial weight) x 100). * Record your observations and data in the designated data section. Results In experiment 5. 1 part A: (Plant cell in Hypotonic, Hypertonic, and Isotonic Solution) In experiment 5. 1 part B: Solution Source| Original Contents| Original Color| Final Color| Color After Benedict’s Test| Bag| Glucose| Cl ear| Blue-Black| Orange| Beaker| I2KI| Light Brown| Light Brown| Light Orange| Control| H2O| Clear| Clear| Light Bluw| In Experiment 5. 2 part A: (Animal Cell in Hypertonic, Isotonic, and Hypotonic Solution) In Experiment 5. 2 part B: (Appearance of Elodea Cells in Solutions â€Å"A† and â€Å"B†) Solution| Appearance/Condition of Elodea Cells| A- Distilled Water| Cell became swollen and burst (Lysis)While others only underwent increased Turgor. | B- Salt Water| Cell shriveled up and appeared bumpy. | In Experiment 5. 3: Sucrose Molarity (Molar) x Percent Change in Weight (grams) Discussion/Conclusions The data collected from each experiment proved my hypotheses to be correct. All supporting evidence proved our ideas to be true. Through the data tables and graphs given above, our conclusions were spot on when compared to our hypotheses. In experiment 5. 1 we believed that the particles of starch were too large to move through the dialysis tubing, however, the glucose and I2KI molecules would be small enough to be able to pass through the selectively permeable membrane. Our results proved our hypothesis to be correct. In experiment 5. 2 we believed that when the animal cells are placed in a hypertonic solution, that the cell would shrivel up and undergo crenation. Yet, if the animal cell were in a hypotonic solution, it would swell, and go through lysis. On the other hand, if plant cells were placed in hypertonic and hypotonic solutions, they would undergo plasmolysis and turgor respectively. Our observations of the ox blood and Elodea plant proved to be correct when examined under the microscope. In experiment 5. 3 we predicted that as the sucrose molarity increased, the percent change in weight of the potato would decrease. We were able to see this trend after gathering our data in our table and transferring that information in the graph provided above. The results that we produced in each experiment matched up with our predictions. We did not receive any unexpected errors or problems during our lab experiment. Our results as we predicted did match up with our pre-lab research and hypotheses. We were able to determine these results through our understanding of the net movement of water to and from the cell. Diffusion and osmosis are forms of passive transport, and with no requirement of energy, we were able to replicate the procedure through our lab work understanding. A slight problem that I found was with experiment 5. 3. After placing the potato segments into their designated sucrose molarities, upon taking them out of the beaker, the potatoes were too fragile and could have been dried out for a significant more amount of time to truly see their change in weight percentage. With the potato segments even being moist, the slightest amount of moisture or water could drastically change the actual weight of the final potato segment. That was however a minor issue and the experiment did prove for my hypothesis to be correct. I did not have any other problems or issues during the other experiments. Upon conclusion of the three experiments, our pre-experiment hypotheses were in fact correct. We were able to see both diffusion and osmosis in work through the eyes of the microscope. During experiment 5. 1 we were able to see the process of osmosis through the dialysis tubing. Experiment 5. 2 showed what happened to both plant and animal cells when placed in hypotonic and hypertonic solutions. We were able to see first hand the process of lysis, crenation, plasmolysis, and turgor. Finally, in experiment 5. , the potato segments showed how when placed in a higher molarity of sucrose, the less weight the potato is able to gain, until it began to lose more and more weight. Through the graph we designed, we were able to easily determine the osmolarity of the potato tuber tissue. In conclusion, all three of our experiments were a success and gave us an in depth look and understanding on the processes of diffusion and osmosis. Literature Cited (References) * Lodish, H; Berk, A; Kaiser, C; Scott, M; Ploegh, H, Bretscher, M. 2007. Molecular Cell Biology, Freeman, United State of America. Wayne, R. 2009. Plant Cell Biology: From Astronomy to Zoology, Academic Press, United States of America. * Lewis, M. 1997. Diffusion, Osmosis, and ATP. Pp. 176-182 in Mallinson, J et al. eds, Integrated Science: Horizons (6th edition), Ginn, New Jersey. * Miller, S. 2006. Animal Cells and Their Function. Pp. 126-148 in Castro, B et al. eds, Zoology (7th edition). McGraw-Hill, Texas * Morgan, G; Carter, M; Dickey, J. 2010. Investigating Biology, Pearson, United States of America. * Cambell, N; Reece, J. 2007. Biology (8th edition), Cummings, United States of America. How to cite Diffusion and Osmosis, Essay examples Diffusion and Osmosis Free Essays Kristen Demaline Bio 1113, Lab 3: Diffusion and Osmosis Osmolarity of Plant Cells In this class, we learned about hypertonic, hypotonic, and isotonic solutions. Hypertonic solutions have a higher concentration of solutes outside of the membrane, hypotonic solutions have a lower concentration of solutes outside the membrane, and isotonic solutions have an equal amount of solutes inside and outside of the membrane (Morgan Carter, 66). When the solute concentration is not equal, the water concentration is not equal, so water will move from a higher concentration to a lower concentration in a process called osmosis. We will write a custom essay sample on Diffusion and Osmosis or any similar topic only for you Order Now In this experiment, we cut 4 pieces of potato, weighed them, and let each soak in a different sucrose solution for about an hour and a half. Our solutions consisted of distilled water (. 0 sucrose molarity), . 1 sucrose molarity, . 3 sucrose molarity, and . 6 sucrose molarity. Our question was â€Å"which solutions are hypertonic, which are hypotonic, and which are isotonic? †. This can all be determined through weight change. We hypothesized that distilled water would be a hypotonic solution, the . 1M would be a hypotonic solution, the . 3M would be an isotonic solution, and the . 6M would be a hypertonic solution. We thought that . M would be the isotonic solution because its molarity is in the middle. If . 3M is in fact an isotonic solution, then the water concentration is the same inside and outside of the membrane and there should be no water movement resulting in no weight change. If distilled water and . 1M are hypotonic solutions, then the concentration of water is hig her on the outside, so water will move into the potato where water concentration is lower, causing a weight gain. Finally if . 6M is hypertonic, then water concentration is lower on the outside, so water will move from the inside of the potato to the solution, causing the potato to lose weight. After about an hour and a half we took the potato pieces out of the solutions they were soaking in, patted the water off of them, and weighed them for a second time. The initial weight and final weight was recorded, which can be seen in Table 1. The potato piece that was soaking in the distilled water had a 3. 1% weight gain, and the potato piece that was soaking in . 1M sucrose had a 2. 1% weight gain. The potato piece had no weight change in the . 3M sucrose solution. And the potato piece that was soaking in . 6M sucrose solution had a 5. 7% weight loss. The weight changes can be easily seen in Graph 1. Table 1: Change in Weight |Sucrose Molarity: |0M |0. 1M |0. 3M |0. 6M | |final weight (g) |16. 4 |14. 7 |17. 7 |13. 2 | |initial weight (g) |15. 9 |14. 4 |17. 7 |14 | |weight change (g) |0. 5 |0. 3 |0 |0. 8 | |%change in weight |3. 10% |2. 0% |0% |5. 70% | Graph 1: [pic] As you can see, the results supported our hypothesis. Distilled water is a hypotonic solution, which makes sense because there is no concentration of solute in it. The water moved to the potato because the potato has more sucrose concentration, meaning a lower water concentration. The potato that was soaking in . 1M sucrose solution also gained weight as an effect of having a lower water concentration inside, but its weight gain percentage was lower because the solution had more solute than the distilled water. The potato soaking in . M sucrose solution had no change because the concentration of sucrose was the same in the potato as it was in the solution, as we predi cted. The potato lost weight in the . 6M sucrose solution because the amount of sucrose inside the potato was less than the solution causing water movement from the potato to the solution. These results clearly demonstrate the process of osmosis. The water moved from a region where concentration is higher to a region where concentration is lower in every case, just like it would in a cell. Of course there is always a possibility of human error in weighing, labeling, and so on. One mistake our group made was that we forgot to look at the time when we put the potatoes in the solution, so we took them out a couple minute after the group next to us took theirs out, since we started at about the same time. When our results were compared to the results of other groups, they still seemed to match up. Repeating the experiment multiple times would give even clearer results. Diffusion of Starch, Salt, and Glucose Diffusion is when molecules move from an area where they are high in concentration to an area where they are low in concentration (Morgan Carter, 66). In this experiment, we tested the ability of certain substances to pass through a semi-permeable membrane in the process of diffusion. Our semi-permeable membrane was dialysis tubing that was presoaked in water. We tied one end of the tubing with string, filled it with a solution that contained starch, salt, and glucose, and then we tied the other end. We weighed it, so we could later weigh it to discover if there was any weight change. We then placed the dialysis tubing into a beaker of distilled water. Our question was â€Å"which of these substances would be able to pass through the dialysis tubing, or semi-permeable membrane? †. After we let the tubing soak for 30 minutes, we could test for the presence of starch, salt, and glucose using 3 tests (iodine test for starch, silver nitrate test for salt, and Benedict’s reagent for glucose). Our hypothesis was that we would find the presence of all three substances in the distilled water. We thought this because we knew that molecules naturally diffuse when surrounded with an area with less concentration, but we didn’t know how much the semi-permeable membrane would interfere. Our other hypothesis was that water would enter the tubing as substances escaped it. We thought that due to osmosis, the water would move from the area of higher concentration (outside the tubing) to the area of lower concentration (inside the tubing). If our hypothesis was correct and all substances made it through the membrane, then we would expect to see the tubing gain weight and the original distilled water test positive for each substance, using our 3 tests, after the 30 minutes. To carry out the tests we had a positive control for each substance. The positive controls allowed us to see the results of the tests when we knew the solution contained the substances being tested for. We filled 3 test tubes with the starch/salt/glucose solution (positive controls) and 3 test tubes with the distilled water that the dialysis tubing had been soaking in. We put three drops of iodine in a positive control test tube, and three drops into a distilled water test tube to test for starch. Then we put five drops of silver nitrate into a positive control test tube, and five drops into a distilled water test tube to test for salt. Lastly, we put five drops of Benedict’s reagent into a positive control test tube, five drops into a distilled water test tube, and placed them both into boiling water to test for glucose. We recorded the color of each, which can be found in Table 2. We also weighed the tubing after it had soaked for 30 minutes and recorded it with the initial weight, which can be found in Graph 2. Table 2: Results of Diffusion Tests Test tube |Initial color |Final color | |starch pos control |cloudy, white |dark purple | |starch experiment |clear |yellow | |salt pos control |cloudy, white |cloudy, white | |salt experiment |clear |cloudy, white | |glucose pos control |cloudy, white |orange | |glucose experiment |clear |orange | Graph 2: [pic] If we look at Table 2 we see that we got the same color in the distilled water as we got in the positive control for the salt test and the glucose test, meaning that the distilled water tested positive for those substances. For the starch test, the positive control turned dark purple, but the distilled water turned yellow, meaning that it tested negative. If these results are correct, then starch was unable to pass through the semi-permeable membrane. This made our hypothesis false, but not completely. We were still correct about the salt and the glucose making it throught the membrane. Our other hypothesis was correct. Graph 2 displays a weight gain showing that osmosis occured, like predicted. Just like with every experiment, there is room for human error. In this experiment, a mistake that could easily be made is with tying the ends of the tubing and making sure there is no leaks. That mistake could even go unnoticed leading to false results, because it makes it look like the substances made it through the membrane when in actuallity the substances accidently spilled into the distilled water. I think these experiments were successful in demonstrating diffusion and osmosis. The diffusion experiment clearly showed that substances move down a concentration gradient until concentration is equal everywhere, unless something is holding the substances back, like a membrane. The osmosis experiment showed that water always moves down its concentration gradient also. They both showed a search for balance, or equilibrium, on a level that is hard to see without investigation. References Morgan, J. G. and M. E. B. Carter. 2013. Energy Transfer and Development Lab Manual. Pearson Learning Solutions, Boston, MA.    |Points |Self-Assessment |Total Earned | |Introduction |2 |  2 |   | |Results |2 |  2 |   | |Figures/Tables |3 |  3 |   | |Discussion |3 |  3 |   | |Total |10 |  10 |   | How to cite Diffusion and Osmosis, Papers Diffusion and Osmosis Free Essays The Effects of Osmosis and Diffusion The experimentation of last week’s lab was in order to test the many effects of diffusion and osmosis amongst four experiments. One such experiment was testing the effects of molecular weight on diffusion in relation to the use of Agar. The methods performed included the use of two acids, HCl and acetic acid. We will write a custom essay sample on Diffusion and Osmosis or any similar topic only for you Order Now Both acids were placed into an Agar-filled dish and, over increments of 15 minutes, data collection was taken based off the diffusion rate and the diameter length of both the HCl and the Acetic Acid. The resulting factor was the HCl exhibited a greater rate of diffusion, directly resulting in a lager diameter. This implies that the HCl ultimately has a smaller molecular weight. The next experiment was based off osmosis of an animal cell; a chicken egg. After submerging two different chicken eggs in distilled water and 10% salt water, once again intervals of 15 minute data collection was taken for a total of one hour. After each interval the weight in grams was taken and then the eggs were placed back into the solution for further analysis. Ultimately, the egg in distilled water exhibited an increase in weight while the egg in salt water was the opposite; a decrease in weight. This conclusion proves that water diffusion occurs from a hypotonic solution to a hypertonic solution. Osmosis in a plant cell was tested by comparing an Elodea cell in pond, distilled, and salt water. After obtaining samples of the Elodea cell and preparing a wet mount of each leaf using all three types of water, observations of the cells in a compound microscope was the next step. From there, comparisons of all three types of solutions in order to determine the apparent differences in osmosis were needed. When examined, the cell in pond water was not as defined; this result implied that water left the hypotonic cytoplasm of the cells causing it to wither in a way. Introduction In order to conduct the experiments of this lab, a hypothesis is no doubt necessary. In reference to the effects of molecular weight on diffusion a person is lead to believe that since the atomic mass unit of Acetic Acid is greater than that of HCl, the rate of diffusion of Acetic Acid will be slower and therefore produce a smaller diameter. As stated by Watson (2011), â€Å"larger molecules diffuse more slowly because of resistance from molecules of the medium. † This â€Å"medium† is the means of passing through the spaces in between a molecule. This was as well stated by (Watson 2011). Reiterating what was described, unlike smaller molecules, which can fit through a medium more easily, in turn allowing for a faster and more sufficient means of diffusion, a larger molecule has the resistance from a specific medium, which in a way is pulling back molecules therefore causing a prolonged time of diffusion. This resistance is a direct correlation and explanation as to why the diffusion rate of a relatively larger molecule exhibits a longer rate of diffusion, as with the comparison of hydrochloric acid and acetic acid, and ultimately the purpose of this experiment. Based on the background information acquired on osmosis of an animal cell, it is safe to assume that after each interval of fifteen minutes, the weight of the animal cell in distilled water will continually grow, while the egg in salt water will decrease in weight. Derived from information provided by (Fisher, Williams, Lineback 2011), an animal cell, which is hypertonic, placed into a hypotonic solution of distilled water will cause water to diffuse into the hypertonic cell, seeing as diffusion occurs from hypotonic to a hypertonic solution. With any type of diffusion process, the particles that are being diffused tend to travel from a concentration that is greater to one that is smaller; moving down in the concentration gradient. This is the direct result of the increase in weight of the animal cell in the experiment. In relation to a chicken egg, the largest living cell, it is predicted that the containing molecules will be too large to pass the membrane and water will flow into the egg (Reece 2011). The matter of the animal egg being placed into a solution of 10% salt is the directly opposite of the above stated. Osmosis within a plant cell placed in pond water will show a wilted cell wall based on the continual impeding force of the water on the wall. Aquatic plants tend to be hypertonic in their natural environment causing the plant to exhibit a â€Å"swollen† or turgid structure. Materials and Methods In order to accurately and sufficiently test the hypothesis of the effects of molecular weight on diffusion, agar was one substance that was used. Agar in the presence of acids turns from a yellowish color to a more violet color. This same dish contained to holes with which two acids could be placed-HCl and acetic acid. From basic chemistry knowledge one knows that the molecular weight of HCl in comparison to Acetic Acid is smaller in size; that information was given from Watson (2011). This is significant because it will later give way to the rate of diffusion of the two different acids. Constant observations, recordings, and measurements were required for this experiment, only in the intervals of 15 minutes. Over a period of one hour it was noticeable that the HCl exhibited a greater rate of diffusion and a great length in diameter, in comparison to acetic acid. The most important factor when dealing with this diffusion experiment, was the methods taken to prove that HCl had a greater rate of diffusion than acetic acid. Initially, soaking a chicken egg in a small solution of acetic acid and 2 parts tap water will allow for better experimentation of the rate of osmosis of an animal cell. The overall scope of this particular experiment was to weigh two eggs using a triple beam balance in order to get an initial weight of the eggs before beginning the process of the lab. After doing so, the eggs were placed into two solutions, one being distilled water and the other 10% salt. Proceeding these steps were the 15 minute intervals of time, and after, a recording of the weight of the egg. This process was done until a total of 60 minutes was reached for both the distilled water solution and the 10% salt solution. After acquiring all results and data, a conclusion could be based. Once acquiring three samples of Elodea leaves, preparing three different wet mounts was the following step. From there, after ten minutes an observation of all the samples under a compound microscope was the following method needed in order to determine the characteristics of the leaves. The leaf in the pond water demonstrated the leaf cell in â€Å"normal† conditions, while the distilled water and NaCl were not â€Å"normal† conditions. Results The findings of the effects of molecular weight diffusion conclude that ultimately the molecular weight of a molecule affects the rate of diffusion directly. The greater the weight, the slower the diffusion process will be; that was the case for acetic acid, and it was in part due to the diffusion of particles through the medium. In addition to that, the measurement of the diameter of both acids also was directly affected by the molecular rate. All the comparisons in the diameter readings of the two acids can be found in table 2. All readings for both acids were taken over an increment of 15 minutes for an hour. In total, HCl produced a larger diameter due to its smaller amu. See table 2. In comparing the affects of distilled water to 10% salt water and the rate of osmosis of an animal cell, the rate of osmosis proved most sufficient in distilled water, rather than in the salt water, with an apparent increasing weight distribution in the distilled water, and a decrease in weight in the salt water. These changes in weight loss and gain are exhibited in Table 1. Even though it is obvious that both eggs exhibited either weight loss or gain, both eggs also showed a sudden spike it the gain or loss around the time frame of 15 minutes and 45 minutes, yet again illustrated in Table 1. Discussion After conducting the diffusion experiment using agar and examining the results, it is apparent what the outcome of diffusion is when comparing HCl and acetic acid atomic weights. It is as well safe to assume the resulting outcomes of future comparisons of two molecules of with different atomic mass units. The use of agar in this specific experiment is much useful due to the properties and characteristics of the extract. The agar, in the presence of an acid, turns from a yellowish color to one that is pink; because of this characteristic, it was possible to measure the distance from the center outward of the agar when placed into a dish of HCl and acetic acid (Watson 2011). As explained before, these measurements allowed for sufficient data in determining the rate off diffusion for both acids. Table 2 will provide a visual for the data that was collected from the experiment. In the end, a conclusion was established that the rate of diffusion was most prominent in HCl, the acid with the smallest amu. Simply the definition of diffusion itself will aid in understanding why molecules of a higher molecular weight will diffuse slower in comparison to one of a smaller weight. Any substance will diffuse down its concentration gradient, the region along which the density of a chemical substance decreases (Reece 2011). It is understood that the molecular weight is how much mass a substance has, and mass can be determined by how tightly packed particles are-density. A molecule with a high mass, ultimately a high density, will illustrate a slower rate of diffusion. With regards to the cell that is the egg, the rate of osmosis proved to be greater in the distilled water as compared to that of the 10% salt. This is in part due to the size of the particles that make up the egg as well as surround the egg. If there is a higher concentration of nonpenetrating solutes in the surrounding solution, then water will tend to leave the cell (Reece 2011). This definition provides an understanding of what is happening to the egg when it is submerged into the 10% salt solution. Comparing the egg to the salt solution, there is a higher concentration of nonpenetrating solute in the salt solution, nonpenetrating being the particles that cannot cross the membrane, and this in return allows water to leave the egg which ultimately causes dehydration for the egg, resulting in weight loss recorded in Table 1. The complete opposite is the case for the distilled water which would result in weight gain for the egg. Literature Cited Fisher, K. , Williams, K. , Lineback, J. (2011). Osmosis and diffusion conceptual assessment. CBE Life Sciences Education, 10(4), 418-429. doi: 10. 187/cbe. 11-04-0038 Reece, J. B. 2011. Campbell Biology. 9th ed. San Francisco (CA): Pearson Education Inc. 125-139 p. Watson, C. M. (2011). Diffusion and osmosis. In Biology 1441 Laboratory: Cellular and Molecular Biology (pp. 76-91). Boston: Pearson Learning Solutions. Tables and Figures Figure 1 percentage change in wait of eggs between 15 minute intervals [pic] |Weight of Egg (grams) | |Tim e Water 10% Salt | |0 75. 60 91. 65 | |15 76. 00 91. 46 | |30 76. 10 91. 39 | |45 76. 10 91. 5 | |60 76. 10 91. 23 | Table 1 A comparison in weight and change of each egg in DI water and a 10% salt solution. |Start time |HCl |Acetic Acid | | |15 min |16 mm |16 mm | | |30 min |18 mm |19 mm | | |45 min |23 mm |22mm | | Table 2 ———————– 60 min26mm23 mm How to cite Diffusion and Osmosis, Papers