After completion of the three exercises of this experiment, all parts of the original hypothesis were supported by the data. With the first hypotheses, the expected outcome was that potassium permanganate, KMnO4, would travel further through the agar plate in comparison to methylene blue, C16H18N3SCl. According to the scatterplot 1.1, after the KMnO4 crystal was placed on one side of the agar plate and thirty minutes had elapsed, the substance had traveled a distance of 3.0 mm (or 1.0 mm/min). On the other hand, after thirty minutes of being on the opposite end of the agar plate, methylene blue had traveled a distance of 1 mm (or .033 mm/min). When comparing these two diffusion rates (mm/min), it is evident that, as foretold in the hypotheses, potassium permanganate achieved a more rapid rate than methylene blue. This can be explained through the comparison of the two compounds’ molecular weight and the weights’ affect of diffusion rate. As previously discussed, particle size has a negative correlation with diffusion rate (Usenko 2016). As KMnO4 has a molecular weight of 157.996 amu and methylene blue being 319.953 amu, it would then be reasonable for potassium permanganate to have this evidently higher diffusion rate due to its smaller molecular size in comparison to methylene blue. With the second part of the hypothesis, it was expected that the only color change to occur would be within the tube and no color change would occur in the surrounding water. This was then
Watch the solute concentration windows at the side of each beaker for any changes in Na+ and K- concentrations. The Na+ transport rate stops before transport has completed. Why do you think that this happens?
The main objective of this experiment is to differentiate between a physical change and a chemical change.
8. The Tubes were observed for a final 5 minutes, noting any color changes in the solutions.
To conclude, the data we have collected from both experiments suggests that Le Chatelier’s principles are applicable and correct. When different substances were added to different solutions, the equilibrium shifted appropriately in order to gain a balance. The shifting of equilibrium resulted in different color changes in different mixtures. In part 2 of the experiment we the aforementioned changes were more easily spotted. We saw the relationship between forward and reverse reactions. When NaOH was added to tube #8 we saw that the color changed from orange into yellow, in order to gain balance but when we added HCl back, the color again changed to orange. Which clearly proved Le Chatelier’s
This is an individual study investigating the process of diffusion, osmosis and active transport. To start you should know that substances are moving in and out of cells of your body all the time. To understand and make sense of the cells of your body, you need to know about the process of diffusion, osmosis and active transport.
The main purpose of this lab was to view the process of diffusion. This was to see how a caterpillar digests its food and what exactly happens in the process in regards to amylase, glucose, etc.
The wavelength of the light should be a different color from the solution’s color. This is because if the color of the wavelength of the light is the same color as the solution’s color, then the color would not be absorbed. The only way that a solution can absorb a color is if the color of the light’s wavelength is its complementary (opposite) color. The color of the light chosen for this experiment was blue because the wavelength was set to 430nm, which corresponds to blue's wavelength. The color of the FeSCN2+ complex ion is blood-red.
The buret might have been leaky resulting in more KOH dropped in the erlenmeyer flask.
In order to assimilate diffusion through a permeable membrane potassium permanganate and methylene blue were used in experiment. The objective was to compare the rates at which the liquid compound of different molecular weight diffused through agar. This was achieved by obtaining agar in a petri dish with two wells to hold the liquid compounds. The rate was measured by time and diameter distance diffused. This process was observed for 60 minutes at 15 minute intervals.
Each solution contained different concentrations as follows: 0.005 mg/mL, 0.010 mg/mL, 0.015 mg/mL, 0.020 mg/mL, and 0.025 mg/mL. Each solution needed to have a volume of 10 mL. Before adding the different concentrations of Coomassie Blue into their separate tubes, the formula C1V1= C2V2 was used in order to determine how much stock solution is needed for the five dilute solutions. Once that number was calculated, a pipette was used to add the amount of stock solution needed for each tube. We then subtracted the amount of stock solution from 10 mL to determine the amount of H2O needed. The calculated amount of H2O was then added to each tube of solution. After doing that, a spectrophotometer was used to determine each solution’s relative absorbance. However, before that, we first had to calibrate the spectrophotometer before determining each solution’s relative absorbance. In order to calibrate the spectrophotometer, a disposable culture tube filled with distilled water was used. We then changed the data rate to 100 and removed the tube with water. In order to determine the relative absorbance, the relative absorbance had to be at 595 nm. Also, during this experiment, an unknown dilution was given to us by the lab instructor. We determined the relative absorbance by using the spectrophotometer and then recorded the results. The procedures for this experiment can be found on page 8 of
The diffusion across a cell membrane is a process of passive and spontaneous net movement of small lipophilic molecules. The molecules move from a high concentration to a low concentrated region along the concentration gradient. The result being a point of equilibrium, this is where a random molecular motion continues but there is no longer any net movement. However, there are things that can affect the rate of diffusion, these being temperature, surface area, concentration, size of the molecule, permeability, diffusion distance and concentration difference. Osmosis is a type of diffusion as it is the movement of water molecules through a semipermeable membrane into a region of higher solute concentration. Equilibrium is reached when the solute concentration is equal on both sides. Water potential is measured in kiloPascals, it is the measuring of the concentration of free water molecules that are able to diffuse compared to pure water, which is 0 kilopascals. It is a measure of the tendency of free water molecules to diffuse from one place to another. The result being, the more free water molecules, the higher the Water Potential. However, Water potential is affected by two factors: pressure and the amount of solute.
Cells are always in motion, energy of motion known as kinetic energy. This kinetic energy causes the membranes in motion to bump into each other, causing the membranes to move in another direction – a direction from a higher concentration of the solution to a lower one. Membranes moving around leads to diffusion and osmosis. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration, until they are equally distributed (Mader & Windelspecht, 2012, p. 50). Cells have a plasma membrane that separates the internal cell from the exterior environment. The plasma membrane is selectively permeable which allows certain solvents to pass through
The final result when all the dye emerges at the downstream side is shown in Figure 1.
The next experiment was to test diffusion in agar solution. A petri dish with a layer of solidified agar had four holes punched in it using a No. 5 cork borer. Three holes were punched in a triangle shape with the fourth hole directly in the middle. There should be 15 mm between each outside hole and the middle hole. The three outside holes were filled with one drop each of potassium bromide, potassium Terri cyanide, and sodium chloride. The middle hole was filled with a drop of silver nitrate. It is very important to make sure that none of the holes overflow. After each has been filled allow to sit for an hour and observe the results.
e. Please answer the following questions about your results: 1. Did you expect water to turn blue-black in the presence of IKI? Why did we test it?