Archives for 2006

When two people fall in love, neither differences in race nor religion can prevent them from tying the knot. Mixed couples become almost blind to their polar lifestyles and backgrounds after forming a serious relationship. Unfortunately, these dissimilarities which begin to become insignificant to the couple are glaring to their families and society. The couple is frequently reminded that they are two separate people from different cultures that should not belong together. Though mixed couples are often scrutinized and put under great pressure from their families and society, the trend of intermarriage will continue to grow and have a very positive affect on the families formed.

For the most part, parents of mixed couples do not accept inter-racial and inter-religious relationships, or are at least hesitant about the idea at first. When Yolanda E.S. Miller, an Asian woman, introduced her Caucasian boyfriend Jim to her family, she said, “He [her father] shook Jim’s hand and grunted while looking away when they were introduced. At dinner, he ignored Jim completely, speaking only in Chinese to my aunt (who, incidentally, was surprised to discover he could even speak Chinese)” (Miller 80). Miller’s father blatantly did not approve of his daughter dating a white male. The fact was that her father most likely had a fear of whites from the racism he experienced as a young Chinese man growing up in America. He was afraid that his daughter would experience the same racism and discrimination he had gone through, and thus did not want his daughter to have relations with a Caucasian. His behavior is understandable considering his past encounters with whites, and this is one of the reasons parents are apprehensive about intermarriage.

Another illustration of when parents are opposed to intermarriage occurred when an Arab man and a Jewish woman announced their relationship to their parents. When Ella, an Israeli Jew, introduced her Palestinian Arab boyfriend, Jamil, to her family, he remarked that “If I had walked in with a bomb in my hand, their reaction couldn’t have been worse” (Chen 34). Israelis and Palestinians are supposed to be fierce enemies, so the fact that their daughter was dating an enemy is the reason for the disappointment and outrage in her family. When society is against an individual, their family is supposed to be there to support them, but in this case the weight of society’s beliefs outweigh their family’s desire to stand behind them. Without their parents support, a marriage between Jim and Ella will be very difficult.

Kyle Spencer also reports about parental disapproval of mixed couples. He says, “That’s a lesson Karen Kildare, a black university recruiting director in Lincoln, Nebraska, learned firsthand when she brought home her college boyfriend, a white guy from an Iowa fanning family. ‘My dad said he was worried I’d become the family’s servant,’ she says. ‘He had this ridiculous mental picture of his baby girl out working in a field for a bunch of white folks’” (132). Again, similarly to the Asian-Caucasian couple, their father showed disapproval of their relationship based on past experience or teachings. People can be quick to judge, and mixed couples often do not gain support right away, if they ever do gain support from their friends and family. While families are usually somewhat against intermarriage, society is what puts the most pressure on mixed couples.

Society is what plants the idea of disapproval of inter-relations to parents when they are growing up. George Yancey, PhD, a black sociology professor at the University of North Texas says, “…the notion [of white supremacy] stayed with us after the [Civil] war, when it was used to legitimize segregation, discriminatory separate-but-equal laws, and legal bans of mixed-race marriages” (Spencer 133). It is understandable to see why a black parent would be uneasy about their daughter dating a white male when they grew up in an era where they were put down by white people. It will take time before hard times are forgotten and mixed couples can gain immediate support from their families.

Besides society influencing parents of mixed couples in the past, society continues to directly put pressure on mixed couples. “When…Taye Diggs and…Idina Menzel received death threats last year that mentioned their biracial marriage, it served as an unpleasant reminder that mixed-race couples are still confronted by prejudice – sometimes in aggressive forms” (Spencer 132). Not all couples receive pressure this extreme from society, but any pressure put on an intermarriage couple could be damaging to a relationship. The couple may not constantly deal with adversity, but they deal with it enough to make it a factor in their relationship.

Inter-religious relationships can be even harder to maintain because of pressure from society. When a Sunni Muslim and a Shiite Muslim married, “Terrorists, most likely from Al Qaeda, destroyed the Shiites’ Askariya Mosque in Samarra, and Shia militants responded by attacking dozens of Sunni mosques, including two in the local neighborhood of Adhamiya” (Dehghanpisheh, Nordland, and Hastings 24). The hatred between the two different religions is intense, which makes it extremely difficult for the couple to live even remotely comfortably. When facing such intense opposition of their marriage from society, what is the couple to do?

While there are many adverse factors towards intermarriage, there are many facts and figures pointing towards an increasing acceptance of mixed couples. Jim Lobe says, “The number of interracial marriages in the United States increased more than tenfold between 1970 and 2000, according to a new report which concludes that U.S. attitudes towards interracial dating and marriage have undergone a ‘sea change’ over the past generation” (32). This shows that the perception of intermarriage is taking a more positive spin in the publics view and that there are advantages to intermarriage. Why else would it be increasing?

With racism and discrimination down, people feel less threatened and are able to explore relationships which may not have been possible in the past. The relationships formed are very close, as the couple must be devoted to deal with any pressure they receive from their family or society. As a result of committed parents, their children are raised in a very close family. The family sticks together and there is a true sense of belonging for the children. The children will have a rich cultural background, which will give them difference experiences growing up. It is good for them to become acquainted with different cultures and gain understanding and tolerance of different people at a young age. Rhonda Ploubis, a wife in an intermarriage, says of her son: “I’m so proud that he will have a background that I didn’t. To have that rich history is wonderful. I don’t, and I sort of regret it” (Glaser 34). Also as a result of intermarriage, the children may grow up learning two languages. This is a bonus that could help them communicate with more people and potentially open up opportunities for them in the future.

With positive and negative effects of intermarriage, a mixed couple must be ready to deal with and prevent bad experiences to get the most of out their marriage. Arthur Blecher says intermarriage parents need to: “Have a clear plan for how you’ll identify or label your child, decide the identity of the household, which may be different from the identity of the child, make all decisions about the child’s identity as a parenting team, and to acknowledge your feelings and discuss them with your partner” (Glaser 34). It is necessary to decide beforehand on how to raise the child in order to reduce and confusion the child may experience about their identity growing up. They need to grow up with a solid foundation of who they are. The parents need to work together and be open in order for the marriage to work. Without communication, arguments could occur if one parent were to make a decision on their own regarding the children or if one parent becomes apprehensive to how their children are being raised. It is necessary to iron out any possible details about the family structure. As long as intermarriage families take these steps, they can be very close positive and productive families. Dealing with discrimination can be difficult, but as long as the parents are close and dedicated, the family they raise will be rewarding in the end.

Works Cited

Chen, Joanna. “‘We’ve Shot Ourselves in the Heart.’.” Newsweek (Atlantic Edition) 136.19 (2000): 34. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Dehghanpisheh, Back, Nordland, Rod, and Michael Hasting. “Love in a Time of Madness.” Newsweek (Atlantic Edition) 147.11 (2006): 24-26. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Glaser, Gabrielle. “MIXED Blessings.” Baby Talk 63.10 (1998): 34. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Lobe, Jim. “Interracial marriages on the increase.” New York Amsterdam News 96.30 (2005): 32-32. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Miller, Yolanda E.S. “Surviving Racial Storms.” Marriage Partnership 18.1 (2001): 80. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Spencer, Kyle. “What’s Interracial Dating Like Today?.” Cosmopolitan 239.1 (2005): 132-135. MasterFILE Premier. 15 November 2006. http://search.ebscohost.com.

Introduction

A spectrophotometer measures the amount of light absorbed by a solution at different wavelengths of light emitted. Beer’s Law says that absorbance is equal to molar absorptivity times the thickness of the sample times the concentration of the sample. Beer’s law also states that conformity of a solution is able to be determined by plotting its absorbances versus its concentrations, and if a straight line results crossing through the origin, the solution has conformity. Using this information, it is possible to determine an unknown concentration of a solution by finding its absorbance, or if given its concentration, its absorbance can be found without the use of a spectrophotometer.

Experimental

First, a spectrophotometer was turned on, allowed to warm up for about 15 minutes, and was set at a wavelength 400 nm. A cuvette filled with deionized water was used for blanking the spectrophotometer. A second cuvette was filled with a solution of potassium permanganate which was provided. Each cuvette was wiped with a Kimwipe before being placed in the spectrophotometer in order to eliminate smudges which could affect the light passing through. The spectrophotometer was blanked at 400 nm and the cuvette with the potassium permanganate solution was placed in, and its absorbance was read and recorded. It was taken out, and the spectrophotometer was then blanked at 410 nm. The cuvette with the potassium permanganate solution was once against placed in the spectrophotometer. Its absorbance was read and recorded again. This process was repeated, increasing the wavelength of the spectrophotometer by 10 nm until it reached 640 nm when recording ceased. The wavelength with the highest absorbance was used for the rest of the experiment.

Four volumetric flasks were then used to make solutions of KMnO₄. Flask 1 was a 100 mL volumetric flask that contained 10 mL of 3.170 x 10^-4 M KMnO₄, which was dispensed into the flask using a buret. Flasks 2 through 4 were all 50 mL volumetric flasks that contained 20 mL, 30 mL, and 40 mL respectively of 3.170 x 10^-4 M KMnO₄. All four volumetric flasks were filled to the line on the neck with deionized water. All the flasks were agitated, and cuvettes were filled with each sample. Each cuvette was placed in the spectrophotometer and their absorbances were all recorded.

Next the unknown was placed into a 250 mL beaker and 10 mL of concentrated nitric acid was added to it. Then 0.5 g of potassium periodate was dissolved in 40 mL of deionized water. This solution was heated with a hot plate in order to aid the dissolving process. The contents of the 250 mL beaker were emptied into this solution and were heated for about 10 minutes, but the solution was never brought to a boil. After heating, the solution was put on ice and brought back to room temperature. A cuvette was then filled with this solution and its absorbance was determined and recorded using the spectrophotometer.

Results

Absorption vs. Wavelength for Maximum Absorbance Determination:

Standard Solutions:

Unknown Number: 14

Wavelength: 530

Calculations

To find the concentration of the standards, I figured out how much the KMnO_4­ was diluted in each volumetric flask. I did this by taking the amount of KMnO_4­ added, then divided by the total volume on the volumetric flask. I then multiplied this percentage by the original concentration of KMnO₄, which was 3.170 x 10^-4. To find the concentration of the unknown solution, I first got the equation of the standard curve line, which was y = 2701.2x – 0.048. I then substituted the absorbance I found for the unknown, which was 0.322, for y. I could then find the value of x, which was the concentration.

Discussion/Conclusions

Potassium permanganate does indeed seem to follow Beer’s Law. When I plotted the absorbances found against the concentrations, I was left with nearly a straight line that goes almost directly through the origin. It is only 0.048 absorbances away from going through the origin, and the best fit line is very close to hitting every point plotted. This is one way to prove conformity and Beer’s Law.

Sources of error in this experiment could occur many different ways. If the cuvettes are not wiped off before being placed in the spectrophotometer, there could be smudges or fingerprints that would cause error. The wavelength on the spectrophotometer had to be set by eye, so there is some room for error there, too. If the dilutions are made inaccurately, that would also cause error in absorption readings. Overall, if anything measured in this experiment was measured inaccurately, that would cause error. Also, if the solution with the unknown in it was boiled, that may cause it to form something different than we wanted to measure and that would cause error, too.

Abstract

Photosynthesis in plants is affected by the intensity of the light the plant is exposed to. For this experiment, DCPIP was added to cuvettes with spinach chloroplasts, which were exposed to an incandescent light at different distances for different intervals of time. After each exposure, the cuvettes were placed in a spectrophotometer set at 621 nm and the absorbance of DCPIP was measured. At 37 mm away from the light, the absorbance decreased at 0.033 absorbances/minute. At 27 mm away from the light, the absorbance decreased at 0.043 absorbances/minute. At 5 mm away from the light, the absorbance decreased at 0.050 absorbances/minute. As the distance from the light increased, the absorbance readings on the spectrophotometer went down at a faster rate. This means that the amount of DCPIP in the chloroplasts decreased quicker as the intensity of light was higher, and that photosynthesis occurs more quickly or slowly depending on the intensity of the light.

Introduction

Photosynthesis is the process that allows plants to survive (Chiras, 1993). It provides ATP (which can be used for energy), starch, cellulose, fats, and nucleic acids among other large molecules, and it consumes CO₂ to produce O₂ (Chiras, 1993). The plant chloroplast cell consists of an inner and outer membrane (Thorpe, 1984). Inside of the cell consists of chlorophyll and stroma. The stroma is a fluid substance comparable to cytosol in animal cells. Chlorophyll are particles that absorb light and pass the energy obtained onto thylakoid disks (Thorpe, 1984). Situated in the membrane of the thylakoid membrane is the electron transport chain. Along the electron transport chain, two electrons from H₂O ­are excited by light in Photosystems I and II to reach a higher energy level. This energy is used to convert NADP+ to NADPH and to drive electrons into to thylakoid space, which creates a gradient. This gradient fuels ATP Synthase, which converts ADP + Pi to ATP. ATP is used for energy in many processes in plant cells. In the experiments performed, DCPIP was added to chloroplast cells, which replaced the NADP+ along the electron transport chain. Using a spectrophotometer, the amount of DCPIP present was able to be determined and tests using variable intensities of light were performed on spinach chloroplast cells.

Materials and Methods

First, a room was insulated from light and the lights were turned off. A green light was used in order to see. Six cuvettes were then obtained and labeled with the numbers 1 through 6. Tube 1 consisted of 0.5 mL chloroplast, 3.0 mL cold buffer, 1.5 mL cold distilled water, and 0.0 mL of DCPIP, which were all dispensed into the tube using a micropipettor. This tube was used as a blank for the spectrophotometer which was set to 621 nm. Tube 2 was used as a control and was covered completely with tin foil in order to insulate it from light. Tube 2 and 3 were filled with 0.5 mL chloroplast, 3.0 mL cold buffer, 0.5 mL cold distilled water, and last with 1.0 mL DCPIP. Immediately after being filled with the DCPIP and agitated, the tubes were both placed in the spectrophotometer and their absorbances were recorded. Tube 2 was first removed from its foil before being put in the spectrophotometer, and it was put back on after the reading. They were than placed 11.5 mm away from an incandescent light for 3 minutes. Their absorbances were again recorded and this was repeated until the control tube came to a constant reading while tube 3 gradually went down. Tubes 4 through 6 were also filled with 0.5 mL chloroplast, 3.0 mL cold buffer, 0.5 mL cold distilled water, and 1.0 mL DCPIP right before being subject to light. Tube tubes were placed 37 mm, 27 mm, and 5 mm away, respectively. Their initial absorbances were recorded and following absorbances were recorded every 60 seconds for 6 minutes was exposed to the light.

Results

Table I:

Table II:

Tubes 2 and 3 were used to prove that it was indeed the light causing the absorbance to go down, and not the heat from the light. Tube 2 was covered with foil to prevent it from being exposed to light and its absorbance stayed constant, while the absorbance from tube 3 which was uncovered went down. As the tubes were placed closer to the light, their absorbances went down quicker, which was expected. The absorbance of tube 6 went all the way down to 0.16, which seemed very low (Table I). Test tube 5’s absorbance went low also, going down to 0.21 (Table I). Test tube 4 had very sporadic readings (Table I). This may be attributed to it not being thoroughly mixed enough.

Discussion

The absorbances readings recorded measured the amount of DCPIP_oxidized in the cells. As photosynthesis occurred, electrons were donated to the DCPIP_oxidized, forming DCPIPH_{2 reduced}. DCPIP_oxidized is able to absorb light from the spectrophotometer at 621 nm, hence that it why it was calibrated at 621 nm. As photosynthesis took place, there was less and less DCPIP_oxidized available for absorbance. That is why the absorbance readings went down over time.

Bidwell (1979) reported that light absorption is not really affected by temperature. The results gained from the experiment were consistent with his findings. When tube 2, which was covered in tin foil, was exposed to the light, its absorbance stayed constant. Though light was not affecting the tube, it could still be heated up. Because its absorbance did not move, this showed that the heat did not affect any of the absorbance readings for any of the test tubes.

Tubes 3 through 6 were all exposed to the light and their absorbances went down over time. The rate at which their absorbances went down increased as their distance from the light source decreased. The intensity of light directly affects the rate of photosynthesis (Bidwell, 1979). Graphs show that the higher the intensity, the higher rate of photosynthesis. The intensity in this experiment was increased by moving the tube closer to the light.

Lastly, the reason a green light was used in order to see was because chlorophyll absorbs all colors of light except for green and yellow (Chiras, 1993). Additional experiments using different colors of light or different light bulbs would be interesting, as the chlorophyll trap different kinds of lights at different rates. This could show what range of the color spectrum chlorophyll accept best.

Literature Cited

Bidwell, R. G. S. 1979. Plant Physiology. (MacMillian Publishing Co., NY, NY) 726 p.

Chiras, Daniel D. 1993. Biology: The Web of Life. (West Publishing Co., St. Paul, Mn) 896 p.

Thorpe, N. O. 1984. Cell Biology. (John Wiley & Sons, NY, NY) 719 p.

Introduction

Enthalpy of hydration is the energy change for converting 1 mol of an anhydrous substance to 1 mol of the hydrated substance. In order to find this number, it is necessary to first calculate the enthalpy of dissolution for each substance separately, and then find the different between the two. The enthalpy of dissolution is the energy change of dissolving 1 mol of a substance in water. It is calculated using temperature changes in the water, heat capacity of the substance, and the weight of the mixture. For this experiment, MgSO₄ and MgSO₄ ∙ 7 H₂O were used and the enthalpy of hydration between the two was calculated.

Experimental

A Styrofoam cup and stirring bar were first obtained and weighed together. This mass was recorded. 100.0 mL of deionized water was measured with a graduated cylinder and then put into the cup with the stirring bar. The cup was again weighed and this new mass was recorded. The cup was then placed on a mixing plate set on medium to high and its temperature was recorded every 30 second for 4.5 minutes. An unknown amount of MgSO₄ salt was added to the cup. The cup kept on the mixing plate set on medium to high and its temperature was recorded every minute for 15 minutes. Finally, the cup was weighed and its final mass was recorded. This process was repeated placing the MgSO₄ with MgSO₄ ∙ 7 H₂O.

Results

Enthalpy of Hydration: -106.6 kJ

Calculations

To find the mass of water used, I subtracted the weight of the cup with just the stirring rod from the weight of the cup with the stirring rod and water. To find the weight of the salt used, I subtracted the weight of the cup, stirring rod, and water from the final weight of the cup. In order to find the moles of solute used, I divided the mass of the salt by its molar mass. To find the change in temperature, I subtracted the initial temperature from the final temperature. In order to find Q, the heat capacity of the reaction mixture, I used the equation Q = – (mass of mixture) * (heat capacity of mixture) * (ΔT). To find the ΔH_dissolution, I used the equation ΔH = Q / (number of moles of solute). Lastly, to calculate the enthalpy of hydration, I subtracted the ΔH_dissolution of the MgSO₄ ∙ 7 H₂O from the ΔH_dissolution of the MgSO₄.

Discussion/Conclusions

I was surprised that while the MgSO₄ salt heated the water, the MgSO₄ ∙ 7 H₂O salt cooled the water down. It was interesting that two substances very close in chemical makeup could have such different reactions in water. My graph for the temperature change of water with MgSO₄ seems to only gradually jump in temperature after adding the salt. I believe this is because my lab partner forgot to turn the mixer on, so the salt was not completely mixing at first. Other than that, the procedure went well. The enthalpy of hydration of -106.6 kJ seems fairly high. Water takes 4.184 kJ to be raised only 1 ºC, so 106.6 kJ seems like a lot of energy.

Introduction

One gram of water takes 4.184 joules of energy to increase its temperature 1 ºC. This is the most energy any substance takes to raise its temperature 1 ºC. In contrast to taking the most energy to raise its temperature 1 ºC, this means that it also takes the longest to cool down. This means that water has the highest heat capacity. It must release 4.184 joules of energy in order to decrease its temperature by just 1 ºC. The heat water releases is absorbed by its environment. Knowing the heat capacity of water, it is possible to find how well its environment insulates it. Also using the heat capacity of water, one can figure out the heat capacity of an unknown substance by putting it in water and measure the temperature change of the water and the unknown substance. In this experiment, this is exactly what was performed.

Experimental

First, an empty Styrofoam cup and lid were weighed and its mass was recorded. 70 mL of room temperature water was then added to the Styrofoam cup and it was reweighed and recorded. The temperature of the water was also recorded. Next, 30 mL of water was heated until boiling and this temperature was also recorded. The boiling water was poured into the Styrofoam cup and the final temperature of the combined water was measured and recorded. The final mass of the cup was also recorded.

For the next part of the experiment, an empty Styrofoam cup and lid were again weighed and its mass was recorded. 100 mL of room temperature water was added to the cup and it was reweighed and recorded. The temperature of the water was also recorded. Next, an unknown metal was heated to about 100 ºC and then poured into the Styrofoam cup. The final temperature of the water was measured and recorded, as was the final mass of the cup.

Results

Identification of Metal: 12

Determination of Calorimeter Constant, B:

Determination of the Heat Capacity of a Metal:

Calculations

For the determination of the calorimeter constant, to find the mass of cool water in the cup, I simply subtracted the mass of the empty cup from the mass of the cup with 70 mL of water. To find the mass of hot water added, I subtracted the mass the cup with 70 mL of water from the mass of the cup with the 70 mL of cool water and 30 mL of hot water. To find the temperature changes, I found the difference in temperatures between the final and the initial readings. I then converted those temperatures to Kelvin from Celsius by adding 273. To find the calorimeter constant, I used the equation B = -C_P(m_CW ΔT_CW + m_HW ΔT_HW) / ΔT_CW.

For the determination of the heat capacity of a metal, I performed the same operation as I did for the determination of the calorimeter constant, only replacing the mass of hot water with the mass of the hot metal. The equation for the heat capacity of the metal was also different. It was C_{P, M} = – ΔT_CW (B + m_CW C_P) / (m_HM ΔT_HM). Lastly, to find the molar mass of the metal, I then divided 25 J/mole K by the heat capacity of the metal, which is the Law of Dulong and Petit.

Discussion/Conclusions

My final results do not seem very accurate. The calorimeter constants seem fairly close, but that difference affected the result of the heat capacity of my metal greatly. If I had gotten the same calorimeter constant for both trials, then the heat capacity of the metals would have came out nearly equal. As a result of the heat capacity of the metals being different, their molar masses were also thrown off. In conclusion, I must have made a mistake in a reading while finding the calorimeter constant.

Something that surprised me was how low the heat capacity of the metal was. Normally I think of metals as being very hot and staying hot, but this experiment proved how metals actually cool very quickly. People usually make this generalization, but they are wrong. I think it is because metals heat up more quickly, so they typically think they stay hot. In actuality, hot water is more dangerous than hot metal.

This study determined whether or not temperature had an affect on CO₂ production between yeast and different sugars. For this experiment, 2 mL of 10% fructose solution, 10% glucose solution, and distilled water were each combined with 2 mL of baker’s yeast. Each of these three solutions was measured for CO₂ production at three different temperatures: 3 ºC, 22 ºC (room temperature), and 42 ºC. None of the solutions produced CO₂ when they were at 3 ºC. At room temperature, the fructose and yeast solution produced 0.37 mL of CO₂ in 60 minutes, while the glucose and yeast solution produced 0.45 mL of CO₂ in 60 minutes. The control sample did not produce any CO₂. At 42 ºC, the fructose and yeast solution produced 1.28 mL of CO₂ in 45 minutes, while the glucose and yeast solution produced 1.33 mL of CO₂ in 45 minutes. Again, the control group did not produce any CO₂. Temperature had a great impact of the production of CO₂. When chilled, the solutions did not even produce any CO₂ at all, but when heated, the solutions produced CO₂ almost four times as fast as normal.

1.33= pipet exhausted all of the yeast

*1 ml. bubble appeared in the pipet

Obesity, a common problem in America, is thought to be fueled partly by sugary, fatty foods sold at fast food restaurants. People generally know that fast food is bad for them, but they continue to eat it. Two extremely overweight teenage girls sued McDonald’s claiming that their food was the cause of their weight gain. Their case was ultimately dropped because they could not prove that McDonald’s food caused their obesity. This lawsuit intrigued Morgan Spurlock, who decided to see if McDonald’s food truly does cause obesity. In order to test this theory, Spurlock embarked on a diet consisting only of McDonald’s food for one month. He entered the experiment in very good physical shape. By the end of the experiment, Spurlock had gained almost twenty-five pounds, acquired heart problems, and his liver was badly damaged. He became very lethargic and had constant headaches. Besides the physical problems Spurlock endured, he also suffered mentally from depression.

Spurlock created a documentary, Super Size Me, showing his experience and how McDonald’s food affected him. The purpose of the documentary was to show the danger of McDonald’s food on a person’s health. The viewer could then decide for themselves whether or not they would continue eating McDonald’s food. Spurlock tried to portray the documentary in an unbiased mood, but for the most part, Spurlock did not do an adequate job of gathering and presenting the information he found in a fair manner. In a Rogerian argument, the person wanting change tells theirs views, but then also tells the views of the defendant, sympathizing with them. By showing knowledge of how the defendant feels, the prosecutor gains trust from the defendant, then suggests a common ground for agreement. By being respectful of the opponent’s ideas and thoughts, the opponent will feel less threatened and be more inclined to change their ways. Spurlock did not treat McDonald’s views and opinions with respect, and thus did not succeed in Rogerian argument.

A way the documentary failed in Rogerian argument was by containing a copious amount of sarcasm. Almost every time Spurlock showed McDonald’s side of an argument, he would present it in a sarcastic way, making McDonald’s look wrong and foolish. He sarcastically ordered and ate his food, which created humor and generally made McDonald’s seem bad. Cartoons and animations shown also added to the whole comical routine. This mood made the viewer take anything McDonald’s said unseriously. If Spurlock were to eliminate sarcasm, the documentary would be entirely different and McDonald’s would not seem nearly as bad as they are presented.

Another way Spurlock failed in creating Rogerian argument was by presenting McDonald’s stance on a subject, and then giving his opinion on the subject directly afterwards. He often showed a fact McDonald’s presented and then trumped it with an even better fact he found, or gave the McDonald’s fact and then asked an open ended question, which would make McDonald’s always look wrong. Spurlock almost never gave his side of the argument first, and then showed McDonald’s side last. If he did show McDonald’s side of an argument last, he would show their argument in a downgrading sarcastic way, not in the confident way he presented his arguments. The way he presented his arguments leaves the viewer thinking that Spurlock was right in every issue discussed.

There are also some specific parts of Spurlock’s experiment that he could have performed better. For example, under almost any diet, one is bound to become overweight and out of shape if they do not exercise. Spurlock seemed to drastically change his daily routine for the experiment. He was in very good physical shape before the experiment, so he should have kept doing whatever he did to stay in shape. If that entailed going to the gym and working out, he should have continued doing that during the month he ate only McDonald’s food. Changing his daily routine most likely skewed the results of the experiment.

Also, most people that eat McDonald’s do not eat it three times a day, and most people do not eat it every day. Spurlock could have shown what would happen if McDonald’s was eaten only once or twice a day, or it was eaten only every other day. It is unrealistic to think that people eat all three meals at McDonald’s every day of the week. By limiting the amount of McDonald’s eaten, Spurlock would not have gone under such a dramatic transformation and McDonald’s would not have looked so bad. If he had eaten McDonald’s food in combination with healthy food, he may have gotten much different results. He also could have gathered information on how much McDonald’s food the obese teenage girls that sued McDonald’s ate, and then went on diet similar to theirs. That would have been a more accurate representation of how much McDonald’s food an overweight customer eats.

Spurlock succeeds in showing how eating only McDonald’s for a month without exercise will affect a person, but he does not succeed in Rogerian argument. If he were to perform the experiment under more normal conditions and present information in a less biased way, then it would be fairer to McDonald’s. It seems that he tried his best to portray McDonald’s in a negative way. Spurlock delivers information to make McDonald’s look naïve and foolish much of the time. The humor he adds makes the documentary more enjoyable and captivating for the audience, but it detracts from its viability. Overall, Spurlock could have done a much better job of portraying McDonald’s in a respectable manner.

Introduction

Acids have a pH between 0 and 7, while bases have a pH between 7 and 14. A solution with a pH of 7 is said to be neutral; it is neither an acid nor a base. When given an acidic solution, it is possible add basic solution in order to neutralize it. To tell if the solution has been neutralized, an indicator such as phenolphthalein is used. The indicator will make the solution change color when it has become basic. In this experiment, a 10% solution of unknown molarity HCl was titrated with 1.00 * 10^-1 M NaOH in order to neutralize the HCl. The molarity of the HCl was then able to be calculated knowing the molarity of NaOH, the volume of NaOH used, and the volume of HCl.

Experimental

First, 25.00 ml of unknown sample of acid was delivered to a 250 mL volumetric flask using a volumetric pipette. The volumetric flask was then filled with de-ionized water to the mark in order to complete the 10% solution. A buret was then filled with 1.00 * 10^-1 M NaOH solution and its starting point was recorded. Next, 25.00 mL of the acid solution was delivered to 300 mL Erlenmeyer flask and 3 drops of phenolphthalein were added. The Erlenmeyer flask was put under the buret and the NaOH solution was dispensed into the Erlenmeye flask until the indicator turned the solution pink for around 15 seconds. The final recording on the buret was recorded, and the process was performed 3 times in order to reduce error.

Results

Molarity of NaOH solution: 1.00 * 10^-1 M

Identification of acid: I

Mean Molarity of Undiluted acid solution, M: 1.01 M

Calculations

In order to find the volume of titrant used in mL, I simply subtracted the initial buret reading from the final buret reading. To convert that volume in mL to L, I divided by 1000, as there are 1000 mL in 1 L. To find the molarity of diluted acid solution, I used the equation M₁V₁ = M₂V₂. M₁ equals the molarity of the NaOH solution used (1.00 * 10^-1 M), V₁ equals the volume of titrant used in L, V₂ equals the volume of acid solution used (0.02500 L), and M₂ is the molarity of the acid solution, which was solved for. To find the molarity of the undiluted acid solution, I knew that a 10% solution was used, so I multiplied the molarity of the diluted solution by 10 to get the molarity of the undiluted solution. Lastly, to find the mean molarity of undiluted solution, I added the molarity of undiluted acid solution from the 3 trials and then divided by 3.

Discussion/Conclusions

The final result of the molarity of the undiluted acid came very close to a whole number, which should mean my results are valid. It is also a very plausible number for the molarity of a solution. The volume of titrant used in my last two trials is nearly exact, so I must have performed them very well. The first trial is probably slightly off, as it was my first time doing a titration. On my first trial I added drops of NaOH too quickly towards the end. It is necessary to add the final drops and half drops very carefully towards the end, as it is a fine line between neutralizing the solution and making it basic. Overall, it was a very tedious experiment that relied on precision in order to achieve viable results.

Introduction

When two aqueous solutions are mixed together, they often react chemically and form products. The chemical reaction may be visible as a change in color from the reactants to the products, the release of gas in the product, or the formation of a precipitate. A precipitate forms when one of the resulting products is aqueous and the other product is insoluble. The insolubility means that the product will be a solid, which usually settles to the bottom of the resulting aqueous solution.

It is possible to determine how much precipitate will form before actually combining the reactants. Using stoichiometry, one can figure out how much precipitate theoretically will be produced. In the lab there are outside factors, which can affect how much precipitate is actually formed. Only under ideal conditions would the actual amount of precipitate formed match the theoretically amount of precipitate formed.

In this lab, strontium iodate monohydrate was synthesized using the following equation: Sr(NO₃)₂ + 2KIO₃ —-> Sr(IO₃)₂ + 2KNO₃. With the knowledge of the starting amount of Sr(NO₃)₂ and KIO₃ used, it was possible to figure out how much strontium iodate monohydrate should be theoretically produced. Then after finding out how much strontium iodate monohydrate actually was produced, the percent yield was found.

Experimental

First, approximately 40.00 ml of 5.00 x 10^-2 M Sr(NO₃)₂ and 50.00 mL of 1.00 x 10^-1 M KIO₃ were put into separate graduated cylinders. They were then combined in a beaker sitting in ice. This was to prevent the strontium iodate monohydrate from becoming soluble in water, as its solubility in water goes up with its temperature. The mixture was then stirred for about 10 minutes, so that all the precipitate could form. The precipitate and supernate were then poured into a vacuum filter, and the beaker was rinsed with ice cold distilled water to get all the precipitate out. The filter paper used in the vacuum filter was first weighed before filtration, then once the filtered precipitate was dry, the filter paper and precipitate was weighed. This whole procedure was performed twice.

Results

Volume of Sr(NO₃)₂ solution used: 39.99 mL (1^st run), 40.25 ml (2^nd run)

Molarity of Sr(NO₃)₂ solution used: 5.00 x 10^-2 M

Volume of KIO₃ solution used: 49.98 mL (1^st run), 49.50 mL (2^nd run)

Molarity of KIO₃ solution used: 1.00 x 10^-1 M

Mass of product, watch glass, and filter paper: 32.04 g (1^st run), 27.32 g (2^nd run)

Mass of watch glass and filter paper: 31.33 g (1^st run), 26.47 g (2^nd run)

Mass of product: 0.71 g (1^st run), 0.85 g (2^nd run)

Mass of Sr(NO₃)₂: 0.68 g (1^st run), 0.82 g (2^nd run)

Number of moles of Sr(NO₃)₂ used: 0.00200 moles (1^st run), 0.00201 moles (2^nd run)

Number of moles of KIO₃ used: 0.00500 moles (1^st run), 0.00495 moles (2^nd run)

Limiting reagent: Sr(NO₃)₂

Theoretical yield of product, moles: 0.00200 moles (1^st run), 0.00201 moles (2^nd run)

Theoretical yield of product, g: 0.875 g (1^st run), 0.880 g (2^nd run)

Percent yield: 78.% (1^st run), 93.% (2^nd run)

Mean percent yield: 86.%

Calculations

In order to find the mass of the precipitate, took the mass of the product, watch glass, and filter paper minus the mass of the watch glass and filter paper. To find the moles of the reactants used, I used the equation Molarity = Moles/Liters and rearranged it to the equation Moles = Molarity x Liters. Before subbing the volume in, I had to convert mL to L by dividing by 1000. To find the limiting reagent, I first had to look at the balanced equation of the chemical reaction, which was Sr(NO₃)₂ + 2KIO₃ —-> Sr(IO₃)₂ + 2KNO₃. Since I knew for every 2 moles of KIO₃ used, 1 mole of Sr(NO₃)₂ was used, I could substitute the actual number of moles of each that were used in the experiment to find the limiting reagent. If KIO₃ was the limiting reagent, then 0.00250 moles of Sr(NO₃)₂ would be needed for the 0.00500 moles of KIO₃, but there were only 0.00200 moles of Sr(NO₃)₂ used, so that made it the limiting reagent.

In order to find the percent yield, I first took the number of moles of Sr(NO₃)₂ used because from the balanced equation, I knew that there would be an equal number of moles of Sr(IO₃)₂ produced. I then found the molar mass of Sr(IO₃)₂, which is 437.43 g, then multiplied by 0.00200 moles, which is the number of moles of Sr(IO₃)₂ theoretically produced, to find the number of grams of Sr(IO₃)₂, theoretically produced (0.875 g). I then took mass of the precipitate strontium iodate monohydrate produced (0.71 g) and needed to find the mass of Sr(IO₃)₂ produced. So I found the percent of Sr(IO₃)₂ that makes up strontium iodate monohydrate by taking the molar mass of Sr(IO₃)₂ (437.43 g) and divided by the molar mass of strontium iodate monohydrate (455.44 g) to get 96.046%. I then multiplied the mass of the product by this to find the mass of Sr(IO₃)₂ actually formed (0.71 g x 0.96046 g= 0.68 g). I then took 0.68 g and divided by the mass of Sr(IO₃)₂ theoretically produced (0.875 g) and multiplied by 100 to find get the percent yield of 78.%. I repeated this for the values found in the second run. For the mean percent yield, I took the percent yields found for each run, added, then up, and divided by 2.

Discussion/Conclusions

My results were fairly close to what they should have been. A mean percent yield of 86.% is probably good considering all the factors that can cause the percent yield to be less than 100%. The Sr(IO₃)₂ could get too warm and wash away in the water, the precipitate could not completely form when mixing the reactants, and some precipitate could become stuck in the beaker and not wash out. Those are factors that are not all easily controlled, so overall my percent yield of 86.% seems plausible when looking at those factors that could affect the results.

If I were to repeat this experiment, I would probably take more time in letting the reactants mix and form the precipitate. That way I could be sure almost all the precipitate actually formed. I would also keep the wash bottle in colder conditions to make sure none of the precipitate washed away.

Abstract

Enzymes are catalysts which lower the activation of chemical reactions, thus making them happen more rapidly. In this experiment, different amount of enzyme and substrate were put in a test tube, then were observed using a spectrophotometer to see how fast the reacted to produce product. It was found that as the concentration of enzyme was increased, the speed of reaction increased. Likewise, it was found that as the concentration of substrate was increased, the speed of reaction increased. As there is more enzyme, it is able to react with more substrate at once, therefore increasing the rate of reaction. When there is more substrate, there will be just as much enzyme, also making the rate of the reaction increase. Thus, higher levels of enzyme or substrate mean there will be a higher turnover rate of product.

Introduction

A catalyst is a substance that lowers the activation energy of a chemical reaction (Zubay et al., 1995). In order words, this means that a catalyst makes chemical reactions happen faster than they normally do. Enzymes are catalysts that speed up reactions in living cells. For example, the enzyme carbonic anhydrase makes the chemical reaction CO₂ + H₂O —> H₂CO₃ happen 10⁷ times faster than it normally does. In this example, the enzyme reacted with CO₂. The substance which an enzyme catalyzes is called a substrate. Enzymes bind to substrates in order to speed the reaction in turning the substrate to a product. When there is a little amount of substrate, there will be a small amount of enzyme, but as the level of substrate increases, the level of enzyme increases. In this experiment, the speed at which enzymes and substrates react was observed.

Materials and Methods

For the first experiment, different enzyme concentrations were tested to see how fast they reacted. A Spec20 spectrophotometer was first turned on and set to a wavelength of 340 nm. A reaction mixture consisting of 0.850 ml distilled water, 1.000 ml buffer stock, 0.100 ml 15 mM NAD+, and 1.000 ml ethanol was then put into the test tube using a micropipettor. This mixture was agitated to mix it together, and the spectrophotometer was then calibrated using this test tube. Once calibrated, 0.050 ml ADH enzyme was added to the test tube mixture and agitated. The test tube was then quickly put into the spectrophotometer and its absorbance readings were recorded. The readings were recorded every 15 seconds for 3 minutes. This process was repeated for 2 more reaction mixtures with adjustments to the amount of distilled water and AHD enzyme included. The second reaction mixture had 0.100 ml ADH enzyme and 0.800 ml distilled water, and the third one had 0.025 ml ADH enzyme and 0.875 ml distilled water.

For the second experiment, different substrate concentrations were tested to see their reaction rates. Once again, a Spec20 spectrophotometer was turned on and set to a wavelength of 340 nm. A reaction mixture consisting of 1.85 ml distilled water, 1.0 ml buffer stock, 100 ul NAD+, and 0 ul ethanol stock was put into a test tube using a micropipettor. The mixture was agitated, then put into the spectrophotometer and the spectrophotometer was calibrated. Once 50 ul of ADH was added to the reaction mixture, the test tube was agitated and quickly put into the spectrophotometer. Absorbance readings were then recorded every 15 seconds for 2 minutes. Another reaction mixture with the same amounts of each substance was made, observed, and recorded. This process was repeated for five more reaction mixtures with differences in the amount of distilled water and ethanol stock used. The amounts of distilled water and ethanol stock for these reaction mixtures were 1.80 ml distilled water and 50 ul ethanol stock, 1.75 ml distilled water and 100 ul ethanol stock, 1.65 ml distilled water and 200 ul ethanol stock, 1.35 ml distilled water and 500 ul ethanol stock, and 0.85 ml distilled water and ethanol stock.

Results

Table I

Table II

The concentration of enzyme had an effect of the reaction rate. As the concentration of the enzyme went up, the velocity went up (Table II, Figure 2). The initial slope also became steeper as the concentration of the enzyme increased (Table II, Figure 1).

The concentration of substrate affected the rate of reaction. As the concentration of substrate went up, the velocity increased steeply then evened out (Figure 4). From Figure 4 (v vs. [S]), the estimated Vmax is 0.0620 umol/min and the estimated Km is 0.0140 mM. From Figure 3 (1/v vs. 1/[S]), the estimated Vmax is 0.0568 umol/min and the estimated Km is 10 mM. The actual Vmax and Km recorded from SigmaPlot were 0.06566 umol/min and 0.01522 mM. The Vmax obtained from each graph are fairly close, but the Km are not very close at all. The Vmax and Km from the v vs. [S] graph are very similar to the actual Vmax and Km obtained from SigmaPlot.

Discussion

Shono and co-workers (1995) observed the rate of reaction versus the concentration of a substrate different from the one used in this experiment. Their graphs resulting from their experiment are very similar to the graph resulting from this experiment. The “velocity vs. substrate concentration” graphs follow the almost exact same curve, but the levels of concentration were higher in Shono’s experiment, resulting in higher rates of reaction. In the “1/v vs. 1/[S]” graphs, Shono’s line seems to have about the same slope, but it crosses the x-axis at a much lower value than it did in the graphs for this experiment.

This can be attributed to error in procedure of the experiment, which caused outlier values the line to be skewed. It was not known these outlier values should have been disregarded until computing calculations for Km and Vmax using the “1/v vs. 1/[S]” graph and comparing to other similar graphs. The Vmax recorded from Figure 3 was fairly close to the Vmax found from Figure 4. The Km from Figure 3, 10 mM, is not very close, however. That value is way larger than the Km found from Figure 4, 0.0140 mM, and the actual Km calculated by SigmaPlot, 0.01522 mM.

From the experiment, the results showed that with a higher concentration of enzyme, the higher rate of reaction. When catalyzing a reaction, the enzyme binds to the substrate (Bolsover et al., 1997). If there is a higher concentration of enzyme, this means that there will be more enzyme to bind to substrate at once, therefore making the turnover rate of substrate to product higher. This is why a higher concentration of enzyme produces a higher turnover rate. The turnover rate begins to slow down and stop as the amount of substrate runs out, and that is why the absorbance rates began to even out in Figure 1. There was a limited amount of substrate that could be converted into product.

As there was a higher concentration of substrate, the rate of reaction increased and then leveled off, as shown in Figure 4. The Michaelis-Menten graph assumes that the enzyme and substrate are in equilibrium (Zubay et al., 1995). Therefore, as there is a higher concentration of substrate, there will be an equally high concentration of enzyme to react with the substrate. As there is a higher concentration of each, the rate of reaction increases. The curve evens off, however. This is because each substrate has a maximum velocity at which it can convert from substrate to product. The enzyme can not catalyze the substrate to turnover faster than this.

The affinity for the enzyme and substrate in this experiment was fairly high. The Km, 0.01522 mM, is a low number. This means the enzyme and substrate reacted very quickly to produce product.

Literature Cited

Bolsover, S.R., J.S. Hyams, S. Jones, E.A. Shepard, and H.A. White. 1997. From Genes to Cells. (Wiley-Liss, NY). 424 p.

Shono, M., M. Wada, T. Fujii, 1995. Partial Purification of a Na+ -ATPase from the Plasma Membrane of the Marine Alga Heterosigma akashiwo. Plant Physiol 108: 1615-1615.

Zubay, Geoffrey, William M. Parson, and Dennis E. Vance. 1995. Principles of Biochemistry. (Wm. C. Brown, Dubuque, Iowa) 863 p.