Effects Of Concentration On The Absorbance Values

Effects Of Concentration On The Absorbance Values Abstract: A 0.2100 M stock solution of cobalt (II) chloride hexahydrate was analyzed using UV-Vis spectroscopy. A series of dilutions of the stock solution were made to analyze the effects of concentration on the absorbance values of cobalt (II) chloride hexahydrate using the UV-Vis spectrophotometer. The copper (II) chloride hexahydrate was found to have the highest absorbance value at an average wavelength of 511.02 nm. The average molar extinction coefficient for copper (II) chloride hexahydrate was found to be 4.5172. Spectroscopic analyses of dilutions of the stock solution were used to create a calibration curve of absorbance versus concentration of the cobalt chloride hexahydrate solution. A solution of unknown concentration was analyzed using the UV-Vis spectrophotometer. The calibration curve was used to determine that the unknown had a concentration of 0.1250 M. Introduction: Ultraviolet/Visible (UV-Vis) spectroscopy analyzes electronic transitions between atoms and molecules. Spectra are produced when electrons in molecules or atoms move from one electronic energy level to another of higher energy. In doing so, the absorbed energy is equal to the difference between to the two levels. Compounds that absorb light in the visible region are colored. Compounds that absorb light only in the ultraviolet region are colorless. Inside a UV-Vis spectrophotometer there are usually two light sources, a tungsten lamp for the visible region (380-800 nm) and a deuterium lamp for the ultraviolet region (10-380 nm). The light source produces a white light ray which contains all wavelengths (all colors). The light ray directed to a monochromator by a mirror. The monochromator is used to separate light into specific wavelengths. Each wavelength corresponds to a different color. The instrument scans through the UV-Vis spectrum, sending different wavelengths of light through the sample. A single wavelength passes into the modulator, which consist of a rotor with mirrors that splits the light into two beams. One beam passes through the sample cell, while the other passes through the reference cell. Both sample and reference beams are redirected by mirrors into a detector. The detector compares their intensities of the two beams and sends a signal to the computer that controls the instrument. The signal is defined as abs orbance, which is a measurement of how much light is being absorbed by the sample at that particular wavelength. The Beer-Lambert law states that absorbance (A) is proportional to concentration of the absorbing species and path length of the medium over a certain time: In equation 1, is the molar extinction coefficient and has units of, the path length of the medium or L, is reassured in centimeters or cm and the concentration of the absorbing species has units of molarity or M. In this experiment a solution of cobalt (II) chloride hexahydrate was analyzed using UV-Vis absorption spectroscopy. The purpose of this experiment is to create a calibration curve of absorbance versus concentration by making series of dilutions of cobalt (II) chloride hexahydrate. The calibration curve will then be used to determine the concentration of an unknown sample. The molar extinction coefficient for cobalt (II) chloride hexahydrate will also be determined using the absorption at the concentrations of each dilution. Experimental Procedure: Using the analytical balance, 2.5072 g of cobalt (II) chloride hexahydrate were weighed and placed into a 50 mL beaker. The purple solid was dissolved inside the beaker using 15 mL of distilled water. The purple liquid was then transferred to a 50 mL volumetric flask with the aid of a funnel. The beaker was then rinsed with another 15 mL portion of distilled water to collect any remaining cobalt (II) chloride hexahydrate left behind and then was transferred to the 50 mL volumetric flask using the same funnel. Additional 20 mL of distilled water were added to the 50 mL volumetric flask to create the stock solution of cobalt (II) chloride hexahydrate. Dilutions of the stock solution were made by transferring 2, 4, 6 and 8 mL of the stock solutions to four labeled 10 mL volumetric flasks. Distilled water was added to fill each flask to the line. The absorbance for each solution was calculated using spectrophotometer. Before any samples were analyzed, a sample containing just water was used to blank the instrument. A quartz cuvette was filled with distilled water and covered. The blank sample was placed in the sample holder in the back of the spectrophotometer. Using the program, the spectrophotometer parameters were set to scan the sample from 650 nm to3 90 nm. The program was also designed to automatically let the user know which sample to place next into the sample holder. After the blank sample was analyzed, the cuvette was rinsed with distilled water first and then with a small portion of the stock solution. The cuvette was then filled with a portion of the stock solution, covered and analyzed using the spectrophotometer. This procedure was repeated for all dilutions. After each analysis, the cuvette was first rinsed with distilled water and then rinsed with a small portion of the following sample. Results: In order to analyze the sample using the spectrophotometer, the compound needs to be present in the aqueous form. The copper (II) chloride hexahydrate appeared purple as a solid. After the 2.507 grams of copper (II) chloride hexahydrate were dissolved in 50 mL of distilled water, the compounds color changed from a dark purple to a pink colored solution. The concentration of the copper (II) chloride hexahydrate stock solution was found using the molecular weight of the compound, the amount of compound used and the amount of distilled water used to dissolve it. Table #1 shows the how the concentration of the copper (II) chloride hexahydrate stock solution was found. When the dilutions were made by taking 8, 6, 4 and 2 mL of the stock solution, the concentration of each dilution decreased proportionally to the amount of stock being added. The intensity of the pink color of each dilution also decreased as the amount of milliliters of distilled water increased. Table # 2 shows how the concentration for each dilution of the stock solution was calculated. The software was programmed to analyze the solutions in the following order, the blank sample, the stock solution (0.2100 M), the 0.1680 M dilution, the 0.1260 M dilution, the 0.0840 M dilution and 0.0420 M dilution. All samples were analyzed in the spectrophotometer, by using quartz cuvettes. The blank sample had no visual results as expected. When the 0.2100 M stock solution was analyzed by the spectrophotometer, the computers monitor displayed the formation of a graph starting at 650.00 nm on the x-axis and 0.00 Absorbance on the y-axis. After the graph passed 580.00 nm, the graphs absorbance values started to increase exponentially. The maximum absorbance value was recorded at 0.9993 and it occurred at maximum wavelength of 511.34 nm. After the was passed, the graphs absorbance values started to exponentially decreased until the graph reached 420.00 nm, after 420.00 nm the graphs absorbance values displayed a slightly constant pattern until the end of the graph at 380.00 nm. Similar results were observed for all the dilutions. The 0.16800 M dilution analysis showed a maximum wavelength of 510.92 nm and a maximum absorbance value of 0.7266. The 0.12600 M dilution analysis showed a maximum wavelength of 511.11 nm and a maximum absorbance value of 0.5703. The 0.0840 M dilution analysis showed a maximum wavelength of 510.98 nm and a maximum absorbance value of 0.4024. The 0.0420 M dilution analysis showed a maximum wavelength 510.75 nm and a maximum absorbance value of 0.1758. Table # 3 summarizes all the maximum wavelengths and absorbance values for the stock solutions and all its dilutions. Figure # 1 (appendix-pg 14) illustrates the graph for each solution. Using the data from table # 3, a calibration curve of absorbance versus concentration can be created. Figure # 2, the calibration curve can be found in the appendix section, page 13. The molar extinction coefficient for copper (II) chloride hexahydrate can be found using data found in Table # 3 and the Beer-Lambert law. By algebraically manipulating the Beer-Lambert equation (A = ÃŽ µ * L *c), the molar extinction coefficient (ÃŽ µ) for copper (II) chloride hexahydrate can be determined by: ÃŽ µ = A / L*c. The molar extinction coefficient for all the solutions can be found in Table # 4. The average molar extinction coefficient for copper (II) chloride hexahydrate was found to be 30445. A solution of unknown concentration was analyzed using the spectrophotometer following the same procedure as all other solutions. The solution of unknown concentration was found to have a maximum wavelength of 511.49 nm and a maximum absorbance value of 0.5715. The concentration of the unknown sample was determined using the equation of the line found on the calibration curve (page 13-Appendix). The unknowns absorbance value of 0.5715 was used as the y-value and the equation was solved for its correspondent x-value or concentration. The unknowns concentration was found to be 0.80 M. Table # 5 shows how the equation of the line from the calibration curve was used to determine the concentration of the unknown. Figure # 3 in the appendix section-pg 14, is a graph of all the solutions tested. In figure # 3, the unknown is easier to identify because the graph is in a landscape format and the x-axis increases by a factor of 20 nm as opposed to a factor of 50 nm in Figure # 1. Conclusion: The spectroscopic analysis of copper (II) chloride hexahydrate made the students familiar with operating a spectrophotometer. Dilutions to a stock solution of copper (II) chloride hexahydrate were made to examine how different concentrations of the compound affected the absorbance values of each sample. The copper (II) chloride hexahydrate was found to have the highest absorbance value at an average wavelength of 511.02 nm. A calibration curve for the concentration versus absorbance of copper (II) chloride hexahydrate was created using the data obtained from stock solution and dilutions using the spectrophotometer. A unknown sample was found to have a concentration of 0.1250 M. The concentration of the unknown was determined by using the calibration curve along with the data obtained from the spectrophotometer. The average molar extinction coefficient for copper (II) chloride hexahydrate was found to be 4.5172. The value for the molar extinction coefficient was determined using the t heory behind Beer-Lambert law and maximum absorbance values from the spectrophotometer. Discussion A different approach to determine the concentration of the unknown involves using the average molar extinction coefficient for copper (II) chloride hexahydrate found in table # 4. By algebraically manipulating the Beer-Lambert equation a formula for concentration can be derived: c = http://www.800mainstreet.com/elsp/Elsp.html

The Women in Dracula Essay -- European Literature Bram Stoker Vampires

The Women of Dracula Throughout the book Dracula, the author, Bram Stoker, portrays many different aspects of women's roles in the 19th century. Since this novel was published many films have been created based on Stoker's story line. Nosferatu, a silent film, depicts the women of the story, other than Mina, as minimal characters. The movie Dracula, filmed in the 1930's, stays very true to the novel, with only minor changes to the characters and plot. All three of the works depict the same women differently, thus changing the complete literary artistic nature of each piece. Mina is the main female character in the novel Dracula. She is the typical Victorian woman--caring, compassionate and completely devoted toward their loved ones (To The Life of the Victorian Women). She is Jonathan Harker's fiancà ©e and later wife, and is faithful to him throughout the entire novel. When Jonathan first meets Dracula, he becomes very ill. Mina quickly runs to his aid. She becomes completely consumed in figuring out why her husband is so terribly sick. She is intensely devoted to him and does not give up until Jonathan is nursed back to good health. In the novel, after Dracula pursues and kills her best friend Lucy, she joins the team of men that are trying to put an end to him. Dracula starts pursuing Mina, and decides to make her his slave. When Dr. Seward saw Mina after her encounter with Dracula, he was very concerned, stating, "When Mrs. Harker came in to see me this afternoon she wasn't the same; it was like tea after the teapot had been watered" (Stoker 240). The search party decides to keep Mina out of the group, so Dracula cannot read her mind and figure out their plan. Mina, putting the search party before he... ... of women. However, in the silent film Nosferatu, the women have more miniscule roles. The movie Dracula shows most of the same aspects that Stoker uses in his novel portray the women characters. While all three of these texts have the same main characters, they show how even the smallest detail can change the entire perception of a character. Works Cited Dracula. Dir. Tod Browning. Perf. Bela Lugosi, David Manners, Helen Chandler, and Dwight Frye. 1931.Videocassette. MCA Home Video, 1984. Nosferatu. Dir F.W. Murnau. Perf. Max Schreck andAlexander Granach. 1922. Videocassette. Crown Movie Classics, n.d. Stoker, Bram. Dracula. Mineola, N.Y.: Dover, 2003. "To The Life of the Victorian Woman." Life of Women. 10 Feb. 2006 http://www.victoriaspast.com/Lifeof VictorianWoman/LifeofVictorianWoman.html.

Ethics in Sport

As George Orwell said, â€Å"Serious sport has nothing to do with fair play. It is bound up with hatred, jealousy, boastfulness, disregard of all rules and sadistic pleasure in witnessing violence. † In other words, sport isn’t just about game play anymore. The athletes we see in serious sport, the people who have acclaimed money and fame, usually expect better treatment from everyone else, they’re spoiled and therefore behave poorly on the basis they believe they can get away with it.This is why it is not only appropriate, but essential for sporting clubs to punish athletes for off field indiscretions, that is, behaviour that displays a lack of good judgement. Sporting clubs should show no lenience towards athletes who choose to put their sporting careers at risk by behaving in childish ways. Their contracts should result in termination, suspension or they should be fined, depending on the circumstance. Athletes who display idiotic behaviour create a financial l oss for their club as well as creating a negative image for them too.And, by being in the public eye, they are setting a bad example for their fans, especially the children who look up to them. Media coverage of off field indiscretions can create a negative image of the club that has employed the athlete involved. The Rugby league’s image problem is at a very bad state and is known to have so many scandals that even a Wikipedia page has been made for their record of off field indiscretions. On Sunday 17th April, 2011 there was a 60 Minutes report that highlighted the battle between AFL and Rugby league for junior participation.The parents that were interviewed admitted that the relatively clean-cut image of the AFL held greater appeal for them, and normally led to them persuading their kids not to choose Rugby league. Rugby players are continuously stained with a poor reputation because of the reckless actions of a very small minority. An athlete represents the club they belo ng to. So, when one member of the team is involved with off field indiscretions they are ruining it for the respectable players, in ways such as losing hard earned sponsorships.When an athlete displays poor behaviour they are initiating a loss of millions of dollars. Now, more than ever, sporting clubs are pressured by their athlete’s sponsors to take appropriate action for off field indiscretions . This is because when an athlete is involved with off field indiscretions their sponsors will dissociate themselves from the club. Tiger Wood’s disgusting adulterous indiscretions in 2010 received worldwide media attention, and the outcome of this negative coverage caused the loss of millions of dollars in sponsorship deals.On another note, long-standing Sydney Roosters sponsor, Samsung, dumped their club in 2009 after a series of off-field indiscretions left them no choice but to detach their brand with rugby league before it tarnished their own reputation. This indicates t hat such contracts should be terminated on the basis that the athlete’s behaviour had a drastic financial effect on the game. In a competitive sporting landscape, no club is in a position to be losing sponsors, nor are they in a position to be losing fans. Athletes are role models to our children.Unfortunately, it is almost unavoidable that children will observe athletes acting aggressively, as the media are irresponsible in over-covering and sensationalizing violent incidents in sport. Sociology professor at Oregon State and author of several published studies’ on athlete’s behaviour, Steven Ortiz, says: â€Å"Spoiled-athlete syndrome begins early in sports socialization. From the time they could be picked out of a lineup because of their exceptional athletic ability, they've been pampered and catered to by coaches, classmates, teammates, family members and partners. As they get older, this becomes a pattern.Because they're spoiled, they feel they aren't accou ntable for their behaviors off the field. They're so used to people looking the other way. † The athlete’s shouldn’t be used to people looking the way, and they simply can’t afford to while they are in the public eye, as role models. In psychology, I’ve learnt about ‘model behavior’ that is, that from a young age we imitate behavior we observe from our role models. In more detail, if they’re behavior is followed by a positive outcome we are more likely to imitate this behavior then if it were followed by a negative consequence.Therefore, if we expose our children to inappropriate athletes that aren’t punished for their off field-discretions – and these athletes happen to be perceived as role models, are we promoting our children to develop an aggressive repertoire of behavior? Many would argue that an off field indiscretion has no impact on the game play of the athlete, and therefore they should not be terminated as punishment from the game because they are a valuable team member.However, the decision by the AFL club, the Brisbane Lions to terminate the contract of star full-forward, Brendon Fevola demonstrates the fact that a player’s off field behaviour can be as much as a consideration as their on-field performance in regards to their employment. Brendon’s controversial antics included embarrassing drunken performances and in The Sunday Telegraph in June 2012 he was quoted saying â€Å"I grabbed a bottle of wine from her fridge and within 15 minutes it was empty.I opened another bottle, drank it, then went for another one. † The fact that the majority of athlete’s sign a code of conduct at the beginning of their careers which outlines what behaviour is expected from player, demonstrates that there are no exceptions and there should be no room for behaviour that doesn’t meet that expectation. It is essential for sporting clubs to punish athletes for their o ff field indiscretions. Any athlete who does not meet the expectation of the club should be terminated as a result.Although it may seem harsh, this is necessary as any idiotic behavior may have a great financial loss as a consequence, and also result in tarnishing their club’s reputation. Also, these athletes are role models to the general public, particularly young children. According to online website, Ranker, the Top 10 Most Popular Athletes published in February 2010, include adulterer Tiger Woods and drug-cheat Lance Armstrong – great role models, right?

Use Of Remotely Sensed Imagery From Landsat Multispectoral...

Data Types and Sources The study will use remotely sensed imagery from Landsat Multispectoral Scanner (MSS), Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) imagery for the periods 1980s, 1990s, 2000s. It will also use Digital Elevation Model (DEM) data from the ASTER satellite for the periods 2010s will be collected and employed for analyzing the spatial and temporal changes in land use land cover in the study area. Water quality data from rivers will be in form of physical-chemical water parameters including temperature, pH, turbidity, conductivity, Biological Oxygen Demand (BOD), and nutrient levels (silicates, nitrogen and phosphorous). Species richness and abundance and total versus fecal coliform bacteria in river water will also be used. Data Collection Pilot Survey A one week pilot survey will be conducted in the study area, focusing on the areas surrounding Ruiru and Ndarugu Rivers to familiarize the researchers with the area, the people and the topography. Informal interviews will also be conducted to collect information that will assist in the preparation of the main study. Acquisition of Satellite Imagery Landsat MSS, TM and ETM+ imagery for the periods 1980s, 1990s, 2000s, and 2010s will be collected and employed for analyzing the spatial and temporal changes in land use land cover in the study area. Other available reference data such as high resolution imagery on Google Earth, aerial photography and topographic maps will be acquired. Food and