bi183.1_postlab1.pdf

RAW DATA

Diffusion

Setup Date Time Distance from edge of well to edge of diffusion

Rate of Linear Diffusion (mm/hour)

Temperature (degrees Celcius)

100% Methylene Blue, Room Temperature

April 12, 2012 2:01 pm (0 mins) 0 0 33100% Methylene Blue, Room Temperature 2:30 pm (0.48

hours)4 8.3 32


4:56 pm (0.92 hours)

4 4.34 32


5:26 pm (1.42 hours)

5 3.52 31


April 13, 2012 9:55 am (14.92 hours)

8 0.54 33


1:06 pm (23.08 hours)

10 0.43 33


2:09 pm (24.13 hours)

10 0.42 33


April 14, 2012 8:38 am (42.63 hours)

11 0.26 33


9:46 am (43.77 hours)

11 0.25 32


10:16 am (44.27 hours)

11 0.24 32

100% Methylene Blue, Refrigerated

April 12, 2012 2:01 pm (0 mins) 0 0 11100% Methylene Blue, Refrigerated

2:30 pm (0.48 hours)

3 6.25 8


4:56 pm (0.92 hours)

3 3.26 8


5:26 pm (1.42 hours)

4 2.82 8


April 13, 2012 9:55 am (14.92 hours)

4 0.27 4


1:06 pm (23.08 hours)

5 0.22 9


2:09 pm (24.13 hours)

5 0.21 8


April 14, 2012 8:38 am (42.63 hours)

6 0.14 8


9:46 am (43.77 hours)

6 0.14 9


10:16 am (44.27 hours)

6 0.14 8


April 12, 2012 2:01 pm (0 mins) 0 0 33

50% Methylene Blue, Room Temperature 2:30 pm (0.48

hours)3 6.25 32


4:56 pm (0.92 hours)

3 3.26 32


5:26 pm (1.42 hours)

4 2.81 31


April 13, 2012 9:55 am (14.92 hours)

6 0.40 33


1:06 pm (23.08 hours)

7 0.30 33


2:09 pm (24.13 hours)

7 0.29 33


April 14, 2012 8:38 am (42.63 hours)

10 0.23 33


9:46 am (43.77 hours)

10 0.23 32


10:16 am (44.27 hours)

10 0.23 32

100% Congo Red, Room Temperature

April 12, 2012 2:01 pm (0 mins) 0 0 33100% Congo Red, Room Temperature

2:30 pm (0.48 hours)

3 6.25 32


4:56 pm (0.92 hours)

6 6.52 32


5:26 pm (1.42 hours)

7 4.93 31


April 13, 2012 9:55 am (14.92 hours)

14 0.94 33


1:06 pm (23.08 hours)

16 0.69 33


2:09 pm (24.13 hours)

16 0.66 33


April 14, 2012 8:38 am (42.63 hours)

25 0.59 33


9:46 am (43.77 hours)

25 0.57 32


10:16 am (44.27 hours)

25 0.56 32

100% Congo Red, Refrigerated

April 12, 2012 2:01 pm (0 mins) 0 0 11100% Congo Red, Refrigerated

2:30 pm (0.48 hours)

4 8.33 8


4:56 pm (0.92 hours)

4 4.35 8


5:26 pm (1.42 hours)

5 3.52 8


April 13, 2012 9:55 am (14.92 hours)

7 0.47 4

1:06 pm (23.08 hours)

9 0.39 9

2:09 pm (24.13 hours)

9 0.37 8

April 14, 2012 8:38 am (42.63 hours)

18 0.42 8

9:46 am (43.77 hours)

18 0.41 9

10:16 am (44.27 hours)

18 0.41 8


April 12, 2012 2:01 pm (0 mins) 0 0 33

2:30 pm (0.48 hours)

3 6.25 32

4:56 pm (0.92 hours)

6 6.52 32

5:26 pm (1.42 hours)

5 3.52 31

April 13, 2012 9:55 am (14.92 hours)

14 0.93 33

1:06 pm (23.08 hours)

15 0.64 33

2:09 pm (24.13 hours)

15 0.62 33

April 14, 2012 8:38 am (42.63 hours)

20 0.47 33

9:46 am (43.77 hours)

20 0.46 32

10:16 am (44.27 hours)

20 0.45 32

Osmosis

Concentra)on Time Elapsed (in minutes) Distance (in cen)meters)

10% 10 2.210%

20 3.5

10%

30 3.5

10%

40 3.1

10%

50 2.5

20% 10 7.520%

20 9.8

20%

30 10.2

20%

40 10.2

20%

50 10.2

Fermentation

Fermentation tubes contained:A - 15 ml of 10% glucose solutionB - 7.5 ml of 10% glucose solution and 7.5 ml yeast suspensionC - 15 ml sucrose solutionD - 7.5 ml of 10% sucrose solution and 7.5 ml yeast suspensionE - 15 ml yeast suspension

Time Amount of gas displaced (distance in cen)meters)Amount of gas displaced (distance in cen)meters)Amount of gas displaced (distance in cen)meters)Amount of gas displaced (distance in cen)meters)Amount of gas displaced (distance in cen)meters)TimeA B C D E

10 mins 0 3 0 3 415 mins 0 4 0 3 430 mins 0 6 0 5 7.51 hr 0 20 0 20 402 hrs 0 78 0 76 9024 hrs 0 139 0 138 139

Setup Color changeA Transparent yellowB More opaque yellow separated from a darker brown liquidC Transparent yellowD Most opaque yellow that distributed evenly across the whole solu)onE More opaque yellow separated from a darker brown liquid

OBJECTIVES

To examine how different compounds have unique solubility in water To recover the solutes dissolved in the previous experiment (dissolution). To determine why some solutes dissolved in a solution can still be re-collected from filtration. To study the concept of simple diffusion To study the factors that affect the rate of diffusion To determine which of the dyes, methylene blue or congo red, would diffuse faster in 5% agar To demonstrate the process of osmosis To determine the effects of concentration gradient to rate of osmosis To determine the point, solution-salinity wise, at which the human erythrocyte will swell maximally and then burst and release its contents To determine how long it will take for this to happen at different solution-salinity levels To determine the rate of fermentation of yeast in different substrates To measure the degree of acidity after fermentation in each of the fermentation tubes.

METHODOLOGY

Dissolution First, three 15mL test tubes and a test tube rack were obtained. Next, solutes, namely Sucrose, Calcium chloride, and Potassium chloride were put into one of the three test tubes. Only small amounts of the solutes were put into the test tube, as in the amount that is enough to fill only the rounded bottom of the test tubes. Then, 10mL of distilled water was put into the test tubes and were then shaken gently. After shaking the test tubes, they were left alone for three minutes. After three minutes, the each of the test tubes was observed for the outcomes of dissolution.Filtration The result was no residue was collected from the glucose and potassium chloride solution. However, although relatively few, there were residues collected from the Calcium chloride solution.Diffusion First, 5% agar was prepared and made to set in six petri dishes in equivalent amounts. Once the agar solidified, a narrow tube with a diameter close to 5 millimeters (mm) was used to bore a hole into the center of each petri dish. Then, methylene blue was prepared in two different concentrations, 100% and 50%. Congo red was also prepared in 100% and 50% concentrations. Labels were prepared for each petri dish containing the name, concentration and location of the dyes, and were placed on the cover of the petri dishes. Additional labels containing the names of the group members were placed on the sides of the petri dish covers. The hole in the center of each of two petri dishes were filled with 100% Congo red, one was to be put in the refrigerator and another was to be left in room temperature. Before one of the petri dishes was put in the refrigerator, the two petri dishes were photographed and the time was recorded. Similarly, the holes of two petri dishes were filled with 100% methylene blue, one to be refrigerated and the other to be left in room temperature. The petri dishes were photographed before one of them was put into refrigeration and the time was recorded. The remaining holes of two petri dishes were filled with 50% Congo red and 50% methylene blue, respectively, and left at room temperature. Both petri dishes were photographed and the time was recorded. The petri dishes were checked 10 times in the span of three days. During checking, the time and temperature of where the petri dishes were stored was recorded. Then, using a metric ruler, the distance from the edge of the bored hole to the distance of the edge of diffusion was measured in mm. Afterwards, the petri dishes were photographed and returned to their location before checking again. All data was tabulated and the rate of linear diffusion was calculated in mm per hour. Three line graphs were created from the data, one graph per day of checking.Osmosis To perform the experiment conducted, two thistle tubes, cellophane, parafilm, two 500 ml beakers filled with distilled water, 50mL each of two NaCl solutions (with a 10% and 30% concentration), and a burette clamp should be prepared. Form a bag by wrapping one end of the thistle tube with cellophane, and by sealing the edges tightly with parafilm. Once the set up has been complete, use a dropper (or a syringe if the thistle tube is too thin) to transfer the salt solution to the cellophane bag. Fill the setup until the solution is visible for observations to be conducted. If leaking occurs as the solution is being transferred, tighten the seal further. Afterwards, support the setup with the burette clamp and immerse the cellophane bag in the beaker of distilled water. Record the displacement of the liquid every ten minutes until no visible changes occur.

Hemolysis The first step was to create the specified solutions, which were 0.2 M sodium chloride, 0.3 M glucose, 0.2 M potassium, 0.1 M calcium chloride, 0.1 M sodium sulfate, and distilled water. These solutions made up the two set-ups, where a test tube with distilled water acted as a control, and the test tube with one of the other chemicals at a time acted as experimental. To these two test tubes, human blood was added and they were both observed. However, the molarities of the chemicals in the second test tube were played with. They were diluted to a three-decimal number, and then the different hemolysis stages were observed namely, starting, developing, and complete hemolysis. The time between these stages were also taken down. To add to that, the turbidity of the solutions in the test tubes were taken note of, to observe the completion of hemolysis characterized by the solutions becoming clear. The solutions were then observed under the microscope to be observed and timed properly. Lastly, the isotonic coefficient and the degree number of ions released upon ionization of the salt in the solution were computed via their formulae and the data from the observations.Fermentation Five fermentation tubes were given different component mixtures: tube A contained 15 ml of 10% glucose solution, B, 7.5 ml of 10% glucose solution and 7.5 ml yeast suspension, C contained 15 ml sucrose solution, D, 7.5 ml of 10% sucrose solution and 7.5 ml yeast suspension, and E contained 15 ml yeast suspension. The rate of fermentation was measured as the amount of gas displaced in the tube and were measured at time intervals of 10 mins, 15 mins, 30 mins, 1 hr, 2 hr, and 24 hrs. An additional test was performed to measure the degree of acidity in each tube. 5 drops of phenol red was added then gently shook. The color change of the solution was recorded.

RESULTS

Dissolution Results showed that only the glucose solution had all the solutes dissolved. As for Calcium chloride solution, only about 60%-70% of the amount added was dissolved. Lastly, for the Potassium chloride solution, only a very small amount dissolved.Filtration The result was no residue was collected from the glucose and potassium chloride solution. However, although relatively few, there were residues collected from the Calcium chloride solution.Diffusion

Table 1. Methylene Blue Rates of DiffusionDye Setup 1 Setup 2 Setup 3Methylene Blue100 %, Room Temperature100 %, Room Temperature 100%, Refrigerated100%, Refrigerated 50%, Room Temperature50%, Room Temperature

Time (hours) Rate of Diffusion (mm/hour)Time (hours) Rate of Diffusion (mm/hour)Time (hours) Rate of Diffusion (mm/hour)0 0 0 0 0 0

0.48 8.3 0.48 6.25 0.48 6.25

0.92 4.34 0.92 3.26 0.92 3.26

1.42 3.52 1.42 2.82 1.42 2.81

14.92 0.54 14.92 0.27 14.92 0.40

23.08 0.43 23.08 0.22 23.08 0.30

24.13 0.42 24.13 0.21 24.13 0.29

42.63 0.26 42.63 0.14 42.63 0.23

43.77 0.25 43.77 0.14 43.77 0.23

44.27 0.24 44.27 0.14 44.27 0.23

Figure 1. Methylene Blue Rates of Diffusion Line Graph

Table 2. Congo Red Rates of DiffusionDye Setup 1 Setup 2 Setup 3Congo Red 100 %, Room Temperature100 %, Room Temperature 100%, Refrigerated100%, Refrigerated 50%, Room Temperature50%, Room Temperature

Time (hours) Rate of Diffusion (mm/hour)Time (hours) Rate of Diffusion (mm/hour)Time (hours) Rate of Diffusion (mm/hour)

0 0 0 0 0 0

0.48 6.25 0.48 8.33 0.48 6.25

0.92 6.52 0.92 4.35 0.92 6.52

1.42 4.93 1.42 3.52 1.42 3.52

14.92 0.94 14.92 0.47 14.92 0.93

23.08 0.69 23.08 0.39 23.08 0.64

24.13 0.66 24.13 0.37 24.13 0.62

42.63 0.59 42.63 0.42 42.63 0.47

43.77 0.57 43.77 0.41 43.77 0.46

44.27 0.56 44.27 0.41 44.27 0.45

0

1.5

3.0

4.5

6.0

7.5

9.0

0 6.25 12.50 18.75 25.00 31.25 37.50 43.75 50.00

Methylene BlueR

ate

of L

inea

r D

iffus

ion

(mm

/hou

r)

Time (hours)

100%, Room Temperature 100%, Refrigerated50%, Room Temperature

Figure 2. Congo Red Rates of Diffusion Line Graph

Osmosis

Figure 3. Osmosis Line Graph

0

1.5

3.0

4.5

6.0

7.5

9.0

0 6.25 12.50 18.75 25.00 31.25 37.50 43.75 50.00

Congo RedR

ate

of D

iffus

ion

(mm

/hou

r)

Time (hours)

100%, Room Temperature 100%, Refrigerated50%, Room Temperature

01.3752.7504.1255.5006.8758.2509.625

11.000

0 6.25 12.50 18.75 25.00 31.25 37.50 43.75 50.00

Osmosis

Tim

e El

apse

d (m

ins)

Distance (cm)

10% concentration 20% concentration

Hemolysis

Table 3. Calculations and Observations for Hemolysis Experiment

100x Magnification

NaCl Lysing concentrationLysing concentrationNone Starting Developing Complete

0.2 M 25 0 0 0 NaCl0.1 M 2 6 5 20.05 M 1 3 4 5 2 M - not clear2 M - not clear0.025 M 0 0 7 12 0.2 M - not clear0.2 M - not cleardH2O 0 0 0 20 0.1 M - slightly clear0.1 M - slightly clear

0.05 M - slightly clear0.05 M - slightly clearKCl 0.025 M - clear0.025 M - clear

None Starting Developing Complete0.2 M 5 6 7 5 KCl0.1 M 0 3 5 120.05 M 0 2 4 13 0.2 M - slightly clear0.2 M - slightly clear0.025 M 0 3 5 20 0.1 M - clear0.1 M - clear

0.05 M - clear0.05 M - clear

CaCl2 0.025 M - clear0.025 M - clearNone Starting Developing Complete

0.1 M 12 5 6 5 CaCl20.05 M 0 0 0 110.025 M 0 0 4 20 0.1 M - not clear0.1 M - not clear

0.05 M - clear0.05 M - clearNa2SO4 0.025 M - clear0.025 M - clear

None Starting Developing Complete

0.1 M 16 0 0 0 Na2SO40.05 M 7 6 5 20.025 M 0 5 6 24 0.1 M - turbid0.1 M - turbid

0.05 M - slightly turbid0.05 M - slightly turbid

Glucose 0.025 M - clear0.025 M - clearNone Starting Developing Complete

0.3 M 21 0 0 0 Glucose0.15 M 4 6 6 130.075 M 1 4 7 25 0.3 M - turbid0.3 M - turbid

0.15 M - slightly clear0.15 M - slightly clear0.075 M - clear0.075 M - clear

Fermentation Only the tubes containing yeast suspension allowed for fermentation. As such, fermentation tubes A and C did not yield any gas displacement. E was observed to have the fastest rate of fermentation. B fermented faster than D but the difference was not so significant. It was observed that as the liquid on the closed arm goes down the level on the shorter, open arm rises. On the elbow of the fermentation flask connecting the two arms, a darker colored solution was found. After 24 hours of fermentation, the gas had already pushed the liquid to spill outside the open arm. Frothing was also observed with least froth observed in setup E. With the addition of phenol red (indicator for acidic/basic pH) and gentle shaking, a change in color was observed. The phenol red dropped on the setups A and C quickly dissociated and produced a transparent yellow. B and E produced a more opaque yellow color and is separated from a darker brown color towards the elbow of the flask. The color took longest to dissociate in E. D produced the most opaque yellow color that was evenly distributed across the whole solution.

DISCUSSION

Dissolution One major factor to the varying dissolution of the compounds is the property of solubility of these molecular compounds. Some solid compounds are held together by relatively weak intermolecular forces which can easily be disrupted by water molecules, hence dissolution. What also happens in dissolution is an exchange in energies from bonds broken and formed. Glucose molecule bonds broken take energy which they get from weak bonds formed from their intermolecular interaction with water which release energy. Simply put, weak bonds that form pay off for the energy needed to break the structures of both solute and solvent. In the experiment, the glucose (apparently a sugar) dissolves well in water, probably because of the little energy that it takes to break the bonds of glucose molecules. As for Potassium chloride and Calcium chloride, although chloride ions are very soluble in water, it probably takes more energy to break intermolecular bonds and so, not all of the molecules get the energy needed to do so, thus incomplete dissolution.Filtration One thing that could explain why some substances passed through the permeable disk and some did not is the size of the molecules. As for the case of the glucose solution, the solute was very well dissolved, and the molecules were small enough to pass through the diskʼs pores. The opposite happened to the calcium chloride solution wherein to begin with, not the entire added amount of solutes dissolved in the water added. Therefore, there could have been undissolved solutes, and were trapped at the pores, and probably the size of the molecules were relatively larger than the glucose, despite the fact that glucose is a lot heavier, molecularly speaking.Diffusion The agar used was 5% agar. Since the medium is solid, both methylene blue and congo red would diffuse slowest in agar, faster in liquid and fastest in gas. If the agar used was 2% agar, both dyes should diffuse at a faster rate because 2% agar contains more water than 5% agar. Congo red diffused faster than methylene blue. The molecular weight of methylene blue is 319.86 while the molecular weight of congo red is 696.68. Ideally, methylene blue should diffuse faster than congo red because smaller molecular weight and particle size diffuse faster than larger ones (Meyertholen date unknown). However, it is possible that congo red is more permeable than methylene blue in 5% agar. To the other component of 5% agar is 95% water. Based on MSDS information, congo red is water soluble but methylene blue is only slightly soluble in water. Therefore, even if methylene blue has a smaller molecular size than congo red, it is more soluble in lipids than water so it would diffuse at a slower rate (STG Lab 2011; Science Lab 2005) As observed in both methylene blue and congo red, the drop in temperature from around 30 degrees to about 10 degrees slowed down the process of diffusion.According to Meyertholen (date unknown), all forms of motion is influenced by heat energy. Heat has the ability to cause random motion in microscopic particles such as atoms and molecules. Therefore, increasing temperature increases movement, allowing diffusion to take place. Decreasing temperature decreases movement, consequently, decreasing the rate of diffusion. For both methylene blue and congo red, the 50% concentration at room temperature diffused faster than the 100% concentration that was refrigerated. At room temperature, for both methylene blue and congo red, 100% concentration diffused faster than 50% concentration. Increasing the concentration of a substance also increases the rate of its diffusion. In simple diffusion, molecules move from a region of higher concentration to a region of lower concentration (McCane date unknown). The 100% concentrations of methylene blue and congo red have 0% water, while the 5% agar has 95% water and is therefore, less concentrated than the two dyes. Since the well containing the dye is very concentrated, naturally, it will move to the region with less concentration and more water. In comparison, the 50% concentrated dyes contain 50% water, and would diffuse slower into the agar containing 95% water.Osmosis Osmosis is the diffusion of water through a semi-permeable membrane. In the experiment conducted, the semi-permeable membrane was represented by the cellophane. It was observed that the fluid levels inside the cellophane bag rose after immersing it in a beaker filled with distilled water. Such an instance can be attributed to the direction of water diffusion during osmosis. Water moves from a lower solute concentration to a higher solute concentration and conversely, from a high water concentration to a low water concentration. As the water continues to diffuse through the cellophane, the water eventually ceases from going up. At this point, equilibrium has been reached – the fluids enclosed in the cellophane bag and in the beaker now have equal water and solute concentrations.

Comparing the two setups, the setup that had the higher solute concentration, hence, concentration gradient had a higher fluid displacement. This can simply be attributed to the aforementioned discussion on equilibrium. The higher the concentration gradient, the slower the equilibrium is reached and thus, the fluid displacement is higher.Hemolysis The tonicity of solutions plays a part in the erythrocyte hemolysis. A solution is said to be hypertonic when the concentration of the solution is larger within the cell. In principle, this will result in the cell shrinking because as osmosis dictates, water will move from a higher to a lower concentration. Due to this rule, hypotonicity on the other hand can be observed when there is a higher concentration of the solution outside the cell. Thus, the cell swells from the influx of solution, to a point where it will already burst due to the pressure applied to the membrane of the cell, the principle behind hemolysis. On the other hand, when these two former conditions are at equilibrium, it is called isotonicity. This just means that the concentrations of the solution inside and outside the cell are very similar if not equal (Remington 2006). As can be seen from the tables, almost all of the starting molarities of the chemicals created an isotonic solution. This means that in most of the set-ups, there was no hemolysis that happened, except in potassium chloride, and calcium chloride. This suggests that in the solutions of potassium chloride and calcium chloride, there was already an imbalance in the concentrations, causing the solutions to become hypotonic (Pal & Pal 2005). This then starts the hemolysis even before the first dilution. A trend in the tables show that the starting and developing hemolysis decreases as the dilution gets smaller. This shows that the solutions become more hypotonic as the number of dilution increased, more specifically the hemolysis was more instantaneous in these solutions compared to the ones before them. This can be strengthened by the outright observations of the solutions, because as can be seen, the solutions became clearer as the number of dilutions increased. This is so because complete hemolysis is characterized by a clear solution (Pal & Pal 2005). Also, the lysing time with 0.2 M NaCl was noted, and it amounted to 4 minutes and 28 seconds. This was observed while adding distilled water into the solution, thus diluting it further, thus driving it to complete hemolysis, explained above. Lastly, the isotonic coefficient was gotten by dividing the molarity at which glucose (non-electrolyte) completely hemolyzed the rbc, characterized by a clear solution, and the molarity at which the sodium chloride (electrolyte) completely hemolyzed the rbc. This then was plugged into the degree of dissociation formula, along with 2 as k, because, when NaCl is dissociated, it will result in two separate ions. The isotonic coefficient simply means that it is the amount of salts to be added to distilled water to make the solution isotonic for rbc. The degree of dissociation simply tells us the fraction of the original solute that has dissociated, in this case, the two ions complete dissociated when the isotonic coefficient is 3.Fermentation A change in the pressure of the tubes results when yeast ferments sugars. This is caused by the production of carbon dioxide which then pushes the solution towards the other arm (Vernier [date unknown]). Only B, D, and E produced gas displacement since these were the only setups containing yeast. Foaming was observed due also to the production of carbon dioxide (Keusch 2003). B (containing glucose) fermented faster than D (containing sucrose) by only a small degree. When yeast fermentation occurs, a simple sugar like glucose is converted to ethanol and carbon dioxide. With a disaccharide like sucrose, the sugar has to be first degraded into its monosaccharide units, fructose and glucose, before it proceeds to fermentation, hence the slower fermentation rate of D (Keusch 2003). E (containing 15 ml yeast suspension) on the other hand, was observed to have the fastest rate of fermentation, indicating that an error must have occurred since there are no sugars to ferment in the first place. The fermentation tube must have not been properly cleaned and sugar residues were left in the tube. The fast rate of fermentation must have occurred since E contained the most amount of yeast. Phenol red is a pH indicator that turns red at or above pH 7 (alkaline) and turns yellow at a pH lower than 7 (acidic) (Clark College [date unknown]). All setups produced a yellow color indicating their acidic nature. Yeast fermentation produces ethanol and carbon dioxide. Carbon dioxide most probably reacted to some components of the solution which yield to acids such as carbonic acid, resulting to the darker yellow color of B, C, and E as compared to A and C. D produced the most opaque color and was distributed all throughout the solution indicating it was the most acidic.

ERROR ANALYSIS

Dissolution There was one peculiar observation during the experiment. Potassium chloride has way more solubility in water than glucose, but as stated, not the entire amount of the potassium chloride put in dissolved. It could be that the amount that was enough to cover the bottom of the test tube went over the threshold of the relative amount of water in it compared to glucose. And changes have been made regarding the solutes used. Since powdered alum, sucrose, and sodium chloride were not available at that moment, the students had to use alternative solutes.Filtration During the experiment, no peculiar findings were observed.Diffusion All calculations for the diffusion experiment were done using a calculator and are a plausible source of error. As seen in the graph for congo red (figure .), there was a sudden spike in the rate of diffusion for the 100% refrigerated setup. One would find this an anomaly in the data, knowing that the 100% refrigerated setup diffused the slowest, the spike at 8.33 mm/hour is significantly higher than the values for room temperature 100% and 50% concentration setups which are both 6.25 mm/hour. The cause of the sudden spike could be attributed to handling of the petri dish because it is possible that portions of the dye may have spilled. Another possible cause for the spike would be the size and shape of the wells bored by the glass tube. Some petri dishes had softer agar, resulting in slightly larger wells that are not perfectly circular in shape. The last possible source of error is estimating the measurements for the methylene blue setup, which is attributed to the visibility of the dye in the agar. The boundaries of the methylene blue were more difficult to see than congo red because the color became very light in the agar. Since the methylene blue was prepared by another group, the proportions of the powder and water may be different that if the group had prepared the dye. Osmosis It can be seen from the containing the 10% NaCl solution that after attaining equilibrium, fluid levels observed from the thistle tube went down. This can be attributed to the presence of leaks. Presence of leaks would cause the fluid enclosed in bag to flow out of the beaker, thus decreasing fluid level. Possible sources of error attributed to leaking are the loosening of the seal on the edges or the ripping of the cellophane bag due to the weight of the solution enclosed.Hemolysis The biggest error that can probably be blamed for is the improper timing of the whole experiment. This is so because, this experiment was done twice due to the invalidity of the blood. The observation of the blood should have been done within ten minutes to prevent inconsistencies in the results because at ten minutes the blood would have been completely hemolyzed in the solutions. This will not only produce inconsistencies, but also inconclusive data.Fermentation E yielded to the fastest rate of fermentation but should not have been so. This is due to the improper cleaning of the fermentation tubes leaving residual sugars for yeast fermentation to occur. It is best to check the tubes for residual sugars before proceeding to the experiment proper. More or less, human errors are the major problem in this experiment.

CONCLUSION AND RECOMMENDATIONS The dissolution of substances rely on the property of solubility where compensation of energies between bonds formed and broken between the solute and solvent occur, and determines the amount of solute that a certain amount of solvent can completely dissolve. For the recommendations, it would be best if the solutes suggested in the protocol were the ones used in this experiment. The solubility of the solutes also affects their filterability. It would be best if the solutes suggested by the protocol were the ones actually used for the previous experiment which was subsequently used in this experiment. Contrary to what was predicted, congo red diffused faster than methylene blue. This is because aside from molecular weight, there are other factors that influence the process of diffusion including the temperature of the environment, the concentration of the solutions, and the solubility of the solutions in the medium used. The agar medium is composed of 95% water. Even though congo red has a higher molecular weight and larger particle size than methylene blue, it diffused at a faster rate because it is water soluble while methylene blue is only slightly soluble in water. Setups in room temperature exhibited faster rates of diffusion that the refrigerated setups.This is because heat increases the movement of atoms and molecules.

Lastly, diffusion by definition is when particles move along the concentration gradient. Therefore, since the agar contains 95% water, more concentrated dyes would diffuse faster than the less concentrated dyes that contain water. It is highly recommended to wait for the gels to set properly before creating wells in the agar. It is also advised to use a cork borer so that the size and shape of the wells are more uniform. Lastly, one should double check all calculated values and, if proficient in Microsoft Excel or iWork Numbers, use those applications in making calculations From the experiment conducted, it can be concluded that concentration gradient is a key factor affecting the rate of osmosis. The higher the concentration gradient, the faster the process proceeds. Points for improvement for the experiment would be to conduct further replicates for an improved quality of data gathered, and to substitute cellophane with a more durable material such as a collodion bag to prevent rips during the course of the experiment. Based on the results, the hemolysis of erythrocytes is dependent on the tonicity of the solution it is in. The amount of salts in the solution or its molarity dictates whether the solution is hypertonic, hypotonic, or isotonic. More specifically it dictates whether hemolysis will occur. Moreover, the timing of the experiment should be precise, due to the sensitive characteristics of the erythrocytes. The experiment should be done with strict time constraints to prevent inconsistencies and inconclusive data. Moreover, with these time constraints, the experiment will be done with more efficiency and it will give the experimenter time to create more trials, to strengthen his hypotheses. The experiment was able to accomplish its objectives although an error was seen in one of the setups, which was most likely due to the inadequate cleaning of the tubes. It is therefore best to check and test for the presence of sugars before proceeding with the experiment. Larger fermentation tubes can also be used since smaller tubes would result to more spillage. Since the foam is an important indicator of gas development, it is important to avoid spillage. If possible, data would be more accurate if the time intervals for measuring the gas displacement would be constant and have fewer gaps as possible. The temperature can be also recorded since this affects the rate of fermentation.

LITERATURE CITED

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McCane R. Lab Exercise 3: Membrane Transport Mechanisms and Osmosis [Internet]. [date unknown]. [cited 2012 April 14]. Available from: http://district.bluegrass.kctcs.edu/rmccane0001/shared_files/137labexercise3.pdf

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Materials Safety Data Sheet: Congo red [Internet]. [2005]. Houston (TX): Science Lab Chemicals and Laboratory Equipment [Science Lab]; [cited 2012 April 14]. Available from: http://www.sciencelab.com/msds.php?msdsId=9927502

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Vernier Software and Technology. Sugar fermentation in yeast. [date unknown]. Biology with Vernier lab manual. Beaverton. [cited 2012 Apr 16]. Available from: http://www2.vernier.com/sample_labs/BWV-12B-COMP-sugar_fermentation.pdf

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