The Effect of Different Molar Mass on the Diffusion on Substances

3. Does the rate of diffusion change over time? How might this affect your calculated diffusion

Cells and molecules in the environment are constantly moving and changing, for cells to function properly there is a need for equilibrium to be met. The size of the cell and the solution outside of the cell affects the rate of diffusion and osmosis in the cell. Cells are constantly trying to reach an equilibrium with the molecules and substances around it, which is why there are such terms as: hypertonic, hypotonic and isotonic. The procedures allowed testing of whether or not surface area or volume increased diffusion and how different substance control diffusion. Cells are constantly moving to reach equilibrium through diffusion and osmosis.

Two variables that affect the rate of diffusion are the MWCO membrane and the solute concentration. Increasing the membrane size and solute concentration will also increase the average diffusion rate. Decreasing the membrane size and solute concentration will reduce diffusion rates and can even prevent all diffusion.

Time) because it had a correlation closest to 1. All three orders were graphed and a linear regression was used to see which graphed order was closest to 1. The order was determined by comparing the concentration and time to the mathematical predictions made using the integrated rate laws. Analyzing each graph and finding each correlation helped determine which graph was closest to 1. The more concentrated a solution is, the higher the absorbance of that solution. This is due to Beer’s Law. The law measures the absorbance of a solution by determining how much light passes through a solution. As the concentration of a solution increases, fewer wavelengths of light are able to pass through the concentrated solution. The absorbance at 60 seconds was 0.573 (Figure 1: Table1). To calculate the concentration (molarity), the Beer’s Law equation was used, Abs = slope(m)+b. Plugging in what is known into the Beer’s Law equation resulted in 0.573 = 3.172e+004 + 0, where the concentration is determined by M = 0.573-0/ 3.172e+004. So, the concentration at 60 seconds using the equation (M = 0.573-0 / 3.172e+004) was 1.824e-5 M. The 1st order graph resulted in k=0.006152 (Figure 1: Graph 1). Other groups also resulted in their decolorization of CV to be the 1st rate

7. Explain how incubation plant tissues in a series of dilutions of sucrose can give an

In performing the proper experimentation, we poured some of the methylene blue substrate in a piece of paper, for ease transport towards the agar plates. We performed it cautiously by not inhaling it, for it is a form of powder. We carefully place the substrate at the center of the agar plates, to ensure that is that there is enough space for diffusion to take place. After the moment we placed the substrate, we carefully placed a transparent ruler under the plate to measure the diameter of the substrate in 0 minutes. We carefully note the time, having a 15-minute interval and record the changes in the diameter of the substrate. We continued it, until we have an hour observation.

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane

Another potential error, which might have occurred, is the temperature fluctuation throughout the experiment. The rate of osmosis will be affected if the temperature in inconsistent, as more heat increases rate of osmosis and cooler temperature decreases rate of osmosis.

In the third stage of this experiment, the density of a liquid was determined and compared to known standards. A 100ml beaker was filled to about half-full with room-temperature distilled water. The temperature of the water in ◦C was recorded in order to compare to known standards later. A 50ml beaker was then weighed on a scale in order to determine mass and recorded. A sample of the distilled water with an exact volume of 10ml was then placed in the 50ml beaker using a volumetric pipette. The 50ml beaker with the 10ml of water was then weighed again and the initial mass of the beaker was subtracted from this mass to obtain the mass of the 10ml of water. With the volume and the mass of the water now known, density was calculated using d = m/V and recorded in g/ml. This process was then repeated to check for precision and compared to standard values to check for accuracy. Standard values were obtained from CRC Handbook, 88th Ed.

The following hypothesis was made in regard to effect of the concentration gradient on the rate of diffusion: The higher the concentration gradient, the faster the rate of diffusion.

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.

When the beetroot sample is heated for a longer period of time, it is exposed to the vigorous and frequent vibrating molecules for a longer duration. This further disrupts the cell membranes making them more fragile, thus more pigment will leak out into the external solution. With more leakage of the betacyanin pigment, the % transmittance should be lower, indicating that the % of light that is able to pass through the beetroot solution should be less as duration heated increases.

Incorporation of assay controls included setting up a spectrophotomer and running the chart recorder with a full-scale deflection before the start of the assay. The set recorder had a corresponding value of 1 for the change in the absorbance. Therefore, prior testing was done to observe whether a change occurred in the readings. This helped to indicate that the results were valid, as they could have been affected by a fault during the setting up of the spectrophotometer. On the other hand this was considered as one of the controls for the experiment. Nevertheless, a new cuvette had to be used for each assay.

Diffusion is the spontaneous movement of particles from where they are more concentrated to where they are less concentrated. For this experiment, a 14 cm glass was filled with cold tap water. A drop of red food coloring was dropped in the cup. A stopwatch was used to measure the time it took for the food coloring to get to the bottom of the cup. The average diffusion rate was .78 cm a second. If a different color was used, I do not think it would have made a difference in the results. The mood of the person experimenting could possibly alter the results. For example, if a person is under stress, they may accidentally squeeze too much altering the rate of diffusion. If the water was warmer, this may have sped the

Diffusion is the passage of solute molecules from an area of high concentration to an area of low concentration (Campbell & Reece, 2005). An example is ammonia diffusing throughout a room. A solute is one of two components in a chemical solution. The solute is the substance dissolved in the solution. The solvent, the other component, is any liquid in which the solute can be dissolved (Anderson, 2002). Diffusion requires little or no energy because molecules are always randomly moving; this is due to their kinetic energy. Diffusion occurs only when there is an imbalance in the areas of