Friday, October 11, 2019
Iso-osmolar Concentration of Carrot Cells Lab Essay
For a more thorough understanding of this lab introduction, the concepts of, iso osmolar, membrane, equilibrium, and concentration gradient evaluated. Iso osmolar can be known as the point in which the substance of experimentation faces no change despite the amount of solute inside the solvent( because the solvent and solute concentration is equal. This is where the line on a graph would cross on the x-axis). Selectively permeable membrane can be defined as a microscopic double layer of lipids and proteins that bounds cells and organelles and forms structures within cells and it controls what comes in and out of the cell. Equilibrium is the state of a chemical reaction in which its forward and reverse reactions occur at equal rates so that the concentration of the reactants and products does not change with time. Before this experiment, we were educated on how osmosis functions. Osmosis is a process which molecules and water take to usually get through a selectively permeable membrane in order to reach equilibrium. It is a passive transport which requires no ATF and water moves from high to low water concentration. When osmosis is completed, there should be an equal concentration o water on both sides of the experiment. We have also learned about the iso osmolar point which is when the concentration of molecules are identical inside and outside. Also, we predicted that if the carrot sticks were placed into higher concentrations of sucrose solutions, then the sticks would loose more water. The concentration of particles inside the carrot cells will be found by having them placed into various different solutions with different sucrose concentrations. This will cause the carrot cells to either lose or gain water as the control tries to reach equilibrium with the solution. By measuring the carrot mass before the experiment and after they sat in the mixture for two days, we are able to observe the change in mass of the carrots. The amount of water the carrot lost or gained would show the percentage of mass change, which then we can use to conclude the concentration of particles inside the carrot. By finding the iso osmolar point, we are able to find the concentration of particles inside the carrot, because the iso osmolar point exhibits the solution that has the same concentration both in the carrot and out. The carrot sticks inside the 0.0, 0.2, 0.4, 0.6, 0.9, and 1.0M sucrose mixtures, will have water enter/leave them. In this experiment, the independent variable was the molarity/sucrose concentration of the solutions the carrot sticks were placed into. The dependent variable was the percentage change of mass for the carrot sticks. For about half of the experiments(4/6), water left the carrot cells causing them to loose mass because there was a uneven concentration of water inside the carrot and outside. In the sucrose solutions in which the carrots lost mass, there was more water inside the cell compared to the outside, causing the water molecules in the carrot sticks to move out into the solution as a result of osmosis. Generally, substances try to spread out and reach the state of equilibrium instead of being concentrated in one area. This is why water enters and leaves the carrots; a result of osmosis. Also, there is a solution of sucrose that is perfect for the carrots sticks, which would result in zero percentage mass change of the carrot. The solution, if it is found, is called the iso osmolar point, which there is no change because there is no concentration gradient. CONCLUSION The results of the lab were fairly accurate because there was no team in the class that had a hugely differing result in their experiment. The 0.0 M sucrose had a +16.71% change in mass as a class average and we had a +21.05% percentage change in mass. The initial mass was 1.9g and the final mass was 2.3g. This happened because the concentration of sucrose inside the carrot was higher than the outside of the cell. The water molecules moved a lot faster into the carrot than the sucrose particles attempting to move out of the sticks through the selectively permeable membrane, thus resulting in a greater mass than the original. The result showed the affects of osmosis, where particles moved to achieve equilibrium. The 0.2 M sucrose had a +8.37% change in mass as a class average and our group and +9.52%. The initial mass for these carrots were 2.1g and became 2.3g when the 2 days had ended. This happened because of the same reason for the 0.0 M sucrose, where the concentration of particl es were greater inside the cell compared to the outside of the cell, causing the water molecules moving into the cell through the semi permeable membrane. However, the solution the carrots were dunked into had a 0.2 M sucrose, unlike the first solution. This caused the mass of the carrot to change less because there was already some particles outside of the cell, allowing for equilibrium to become reached a lot faster than 0.0 M sucrose. In 0.4 M sucrose, there was a class average of -2.34% and we had -4.76%. The initial mass was 2.1g with a final mass of 2.0g. This was the first solution to have a negative percentage change in mass from the other six. There was a decrease in mass of the carrot because water had moved from the carrot sticks into the solution around is trying to achieve equilibrium. The water molecules had moved from high concentration into lower concentration, moving our of the carrot cells, causing them to lose mass. The 0.6 M sucrose solution had a class average of -11.84% change in mass while we had a -9.52% change in mass. The initial mass was 2.1g and the final mass was 1.9g. This occurred for the same reason that 0.4 M sucrose lost mass; the carrot sticks had a higher concentration of water compared to the solution it was in, causing it to lose water as the H20 particle slide out using the selectively permeable membrane. The mass loss was greater because the difference in sucrose levels were greater, demanding a greater amount of water from the carrots for equilibrium to be achieved. 0.8 M sucrose had a class average of -15.13% and 1.0 M sucrose had a -20.06% change in mass. These two also occurred because of the same reason 0.4 and 0.6 M sucrose lost mass. But, there was a larger amount of water needed to be transferred out in order to reach equilibrium the higher the sucrose level was. This lab proved the osmosis theory very well, because all six experiments had accurate results because osmosis had occurred in every one of them. Osmosis has the tendency for water to move through the semi permeable membrane from a lesser concentration to a higher concentration(of solute), thus equalizing concentrations on each side. The carrot stick lab showed water moving from inside the carrot to out into the solution because there was a higher concentration of sucrose outside the carrots. Trying to reach equilibrium, the water molecules transferred out into the solution. By graphing the data out, we were able to find out the iso osmolar point of the carrot sticks. We got the result of 0.4 M sucrose as the point. This number represents the sucrose concentration the carrots would already have equilibrium at, and no need for more osmosis because the concentration of sucrose and water is same or very close to same already. Thus, there wouldnÃ¢â¬â¢t be any or little change in mass of the carrot sticks. There were many possible sources of error in this experiment however, because first of all, the equipment were not brand new. The equipment we have used had been used of various types of labs over the years, and had the chance that they were not properly washed, leaving traces of precious labs. The solutions that got intermixed with these chemicals we were not aware of, could of changed the data and threw us off. There is no idea what kind of chemical was on the glasses, so we could of prevented this by experimenting with never used equipment, or by using very well cleansed ones. By having extra sucrose or any other substance on the beakers and tubes, the solution would have become more hypotonic, thus there would be more movement through the membrane and therefore more mass would be lost or less mass would have been gained. This is because the left over sucrose in the beaker adds to the concentration of solute. Another source of error could of happened while blotting the carrots onto a tissue after the two days of waiting time. The carrots that were blotted onto the tissue paper probably lost water, and depending on the strength of the person blotting the carrots, they may have squeezed them too hard, altering results from what would have come out. This could of been fixed by having the carrot sticks pulled out by tweezers instead of draining them and picking them up by hand. Finally I think another source of error was temperature, because the temperature day by day would differ. The changing temperature might have caused data to change as of if they were to be placed into a room of constant temperature of the experimenting time. ANALYSIS If you threw a carrot into a jar of pure H20, would the carrot shrink or swell? Explain. I think if we threw a carrot into a jar of pure H20, the carrot would swell up. The carrot cell is also a plant cell, which flourishes best in a hypotonic solution unlike animal cells. The carrot cell wouldnÃ¢â¬â¢t explode unlike animal cells because they are equipped with cell walls which the animal cells lack. The cell wall stops the cell from exploding inside pure water. Instead, they are happiest inside pure H20. They are at a stage called turgid which is their normal state. In winter icy roads are often treated with salt. Why is this likely to lead to the death grasses along the roadside? During winter, when the roads are treated with salt, the environment around it takes damage. The salt is used so that the salt would Ã¢â¬Å"meltÃ¢â¬ the snow . The snow would treat the salt and H20 molecules would stick onto the salt molecule, separating from their Ã¢â¬Å"ice boxÃ¢â¬ affect and causing them to melt. However, the salt would also stick onto the grasses along the roadside and suck their life out, in simpler terms. The salt on the grass would have a 100% salinity while grasses in comparison would have a much lower salinity percentage. Because the grass would be a hypotonic solution compared to the salt, it would loose water. Thus the environment would be hypertonic. In effort to reach equilibrium with their surroundings, the grass would have the water pulled out of them towards the salt. Introduction MLA citation Ã¢â¬Å"Diffusion.Ã¢â¬ And Osmosis. N.p., n.d. Web. 27 Jan. 2013. .
Posted by Amada Mayhew at 7:32 PM