Determination of Vitamin C Concentration by Titration

Determination of Vitamin C Concentration by Titration Vitamin C (Ascorbic acid) is a necessary nutrient in the human diet. Fruit juices are among the most common consumer items taken to meet our daily requirements of ascorbic acid. Vitamin C can be determined in food by use of an oxidation-reduction reaction. The redox reaction is preferable to an acid-base titration because a number of other species in juice can act as acids, but relatively few interfere with the oxidation of ascorbic acid by iodine. This method determines the vitamin C concentration in a solution by a redox titration with potassium iodate in the presence of potassium iodide. The excess iodine is back titrated with thiosulfate (S2O32-). Starch solution is used as indicator. Iodide ions reduce iodate ions producing iodine in an amount equivalent to the iodate. The principal reactions involved are shown by the following equations. Generation of iodine: IO3- + 5I- + 6H+ → 3I2 + 3H2O Titration of iodine with thiosulfate: I2 + 2S2O32- → 2I- + S4O62- The reaction of iodine with ascorbic acid is shown in the following equation: C6H8O6 + I2 → C6H6O6 + 2I- + 2H+ Ascorbic acid is oxidized to dehydroascorbic acid EXPERIMENT Apparatus burette (50 mL), volumetric flasks (250 mL, 100mL), beaker (400 mL), pipette ( 10 mL, 25 mL), Erlenmeyer flasks (250mL) Reagents oxalic acid, C2H2O4.2H2O, potassium iodate KIO3, sodium carbonate, Na2CO3, sodium thiosulfate pentahydrate, Na2S2O3.5H2O, sulfuric acid, H2SO4, potassium iodide, KI, starch indicator solution (2% w/v in distilled water), apple juice Preparation of Na2S2O3 and KIO3 solution Na2S2O3.5H2O and Na2CO3 were weighed 1.8613 g and 8 mg respectively to prepare exactly 250 mL of 0.03M sodium thiosulfate solution. Dilution of 0.25 g KIO3 in 250 mL volumetric flask was done. Standardization of Sodium Thiosulfate 2 g of KI and 10 mL of 0.6M H2SO4 were added into 250 mL Erlenmeyer flask after 25 mL of KIO3 was pipette. This solution was titrated with sodium thiosulfate solution until the initial brown color of the solution turns to pale yellow. 2 mL of starch indicator was added and the titration was completed at the disappearance of the blue color. Titration was repeated 2 times. Preparation of sample 0.1 gm of oxalic acid was added into 50 mL of apple juice after it was pipette then the sample juice was diluted in a 100 mL volumetric flask. Titration of sample 2 g of KI and 10 mL of 0.6M H2SO4 were added into Erlenmeyer flask after 25 mL of KIO3 and 25 mL of diluted sample were pipette. The solution was titrated with standard Na2S2O3. 2 mL starch indicator was added just before the end point. The titration was repeated 2 times. RESULT AND DISCUSSION The molar concentration of standardize solution and vitamin c studied are shown in summary data report sheet and the all calculations are shown in appendixes. Volumetric analyses based on titrations with reducing or oxidizing agents are very useful for many determinations one of the example is iodometry titration. It was performed using visual indicator that is starch indicator to determine the end point. Starch forms a not very reversible complex with I2 that is a very dark-blue color. The color reaction is sensitive to very small amounts of iodine. Iodine is a moderately strong oxidizing agent and a weak reducing agent. When an excess of iodide is added to a solution of an oxidizing agents, I2 is produced in an amount equivalent to the oxidizing agent present. This I2 can therefore, be titrated with a reducing agent and the result will be the same as if the oxidizing agent were titrated directly. The titrating agent used is sodium thiosulfate. The oxidizing agent not directly titrate with the thiosulfate because strong oxidizing agents oxidize thiosulfate to a oxidation states higher than that of tetrathionate. The end point is detected with starch. The starch is not added in the beginning of the titration when the iodine concentration is high. Instead, it is added just before the end point when the dilute iodine color becomes pale yellow. The reason for using acid is that reactions between many oxidizing agents and iodide are promoted by high acidity. Sodium thiosulfate solution is standardized iodometrically against a pure oxidizing agent that is KIO3. from the volume of titrant used to titrate the primary standard, the molar concentration of the titrant can be calculated. The calculations that involve in these data are base on volumetric analysis which consists of titration and standard solution that means need stoichiometric calculations. The data of standardization of thiosulfate in term of volumes sodium thiosulfate have low accuracy because the differentiation between readings quite obvious compare to volumes of sodium thiosulfate in determination of vitamin C. The data of the experiment is compared to the true data. The true data state that the content of vitamin C mg per 100 mL is 15 mg but in the experiment is 0.8096 mg / 100 mL. This is because the vitamin C is decompose by heat. The diluted sample is prepared too earlier. There are several errors that might be occurred in this experiment. One of that is systematic error which means error in burette reading. The sources of systematic error consists of three types ; instrument error, method error, and personal error. Personal error occurred to the operator of equipment especially in sensitivity in color changes. For example in this experiment the color changes involve is brownish to pale yellow. Whereas the method error occurred when the reaction does not complete. Even the instrument also can cause the error especially when the end of burette and pipette are blocked by something. Instrument errors can minimize by good maintenance of equipment. To observe the color changes when do titration in analyte put the plain white paper at the bottom of conical flask. When taking burette reading always read at the meniscus and the reading of pipette as well. The error in data can be overcome by applying statistical tests on data for example find the standard division and mean. To apply this test carries out replicate measurements. In this experiment we do triplicate. CONCLUSION The molarity of KIO3 is 4.6728 x 10-3 M. The molarity of standardize thiosulfate is 0.0278 M and the content of vitamin C in mg/100 mL is 0.8096.

Our Town :: essays research papers

Our Town, by Thornton Wilder, is an American classic, expressing with warmth and humor the eternal truths of human existence. It is a heartening, compassionate glimpse of that time before the Great Wars; before our innocence was lost forever. From the time of its first performances in 1938, it has continued to be regarded as one of the best representations of life in America and of the richness of our theatre world. For decades it has remained a landmark of theatrical craftsmanship and a loving picture of American life. Winner of the Pulitzer Prize, Our Town depicts pathos set against a background of centuries of time, social history, and religious ideas. As the Stage Manager (who functions as a Greek chorus in the drama) says: "This is the way we were in our growing-up and in our marrying and in our doctoring and in our living and in our dying." Our Town is set in 1901 in Grover's Corners, New Hampshire, where the Gibbses and the Webbs are neighbors. During their childhood George Gibbs and Emily Webb are playmates and their lives are inextricably woven together as neighbors' lives are likely to be. But as they grow older they pass into a state of romantic (and embarrassing) interest in one another. George proposes to Emily in the drug store over an ice cream soda, and they are married with all the good folks of Grover's Corners in attendance. But George and Emily's happiness is short-lived. Emily dies in childbirth and is buried in the town's cemetery on a rainy, dreary day. There she is reunited with those friends and neighbors who have died before her, and who help her acclimate herself to her new existence. In one of the most vital scenes in modern theatre, the peace and quiet of death, which can never be understood by the living, is portrayed. Our Town is not just about Emily and George and, indeed, is not just about a small town in northern New England a hundred years ago. Our Town is a play about what we (and Thornton Wilder) thought America and Americans were. As we are about to take a head-long leap into the next century we are forced, not only to look ahead to what we might become, but to turn and look back at what allowed us to arrive at this threshold of the new millennium.

Red Cliff and Early Chinese Notions

Red Cliff and Early Chinese Notions Introduction The philosophies of early Chinese thinkers differ greatly from the mindset of modern day philosophers. The four major philosophies of China, Confucianism, Mohism, Taoism and Legalism arose primarily during the Warring States era from 475 BC to 221 BC. Following the end of the Qin Dynasty and the fall of Qin Shi Huang, Confucianism became the dominant philosophical school in China.Confucianism represented the teachings of Chinese philosopher, Confucius, concerning the fields of ethics and politics and emphasizes on personal and government morality, humaneness and one’s duty to family and society. Following the popularity of Confucianism and the death of Confucius, the creation of The Analects or Lunyu , was written by Confucius’ followers and disciples in the Warring States period. His teachings were the first to introduce the concept of meritocracy which considers that one’s status in society should not be determi ned by ancestry, wealth, or friendship but rather on education and one’s character.Confucius also explores notions on human nature and self cultivation and the purpose of human existence. This paper will focus on early Chinese philosophies of the relationship between the individual and the state and the relationship between man and nature with references and examples from the film, Red Cliff. The Relationship between the Individual and the State The three core concepts of Confucianism, â€Å"filial devotion (xiao), humaneness (ren), and ritual decorum (li)† (Sources of Chinese Tradition, p. 3) embed the behavioural standards and expectations of how a person should practice these virtues. Furthermore, the three essential values integrate into Confucius’ views on government as well. Filial piety practiced within one’s family translates into how much one is willing to give to society which results in the stability of a state. Humaneness observes the importan ce of a ruler treating his people as how he would want to be treated if he were in their position. In Confucius’ perspective, ritual offers a sense of respect s rites are a mean of expression of a leader’s morality and also â€Å"encourages a sense of dignity and responsiveness among the people† (Sources of Chinese Tradition, p. 43). Filial piety ? is considered the most fundamental of all Confucian teachings. The term can have a broad meaning that not only includes the obedience a child must show for his parents but also respect that should be shown to the living and dead. Filial piety develops into five relationships: ruler to ruled, father to son, husband to wife, elder brother to younger brother, and friend to friend.When subjects respect their ruler and the ruler respects the Heavens, the state will in turn thrive and prosper. From The Analects, Confucius states, â€Å"If a ruler himself is upright, all will go well without orders. But if he himself is not upright, even though he gives orders they will not be obeyed†. The concept of filial piety is displayed in many different ways in the film, Red Cliff. Because of the compassion and brotherhood the southern warlord, Liu Bei, has shown towards his subjects, they were prepared to sacrifice their lives for him and the state.Because Liu Bei has treated his ministers and warriors with respect, as a result, they willingly followed his leadership. Conversely on Cao Cao’s side, his subjects were obedient towards him but only because they were afraid of him. They know not to trust Cao Cao because of his apprehensive and suspicious character that could result in impulsive decisions to kill anyone without any reason or justification. Loosely quoted from Zhuge Liang, â€Å"Although Cao Cao leads a large army, the majority surrendered to him so they are not as trustworthy. † He has not shown humaneness ? o his subjects, therefore they were not motivated to fight for him. Anot her example of filial piety and the relationship between the individual and the state is displayed through Xiao Qiao’s decision to cross over to Cao Cao’s camp in order to buy time for the Southerners. Her duty to her husband and the state required her to forsake her personal interests including her life, her child’s life, and her relationship with her husband, for the greater good. â€Å"This is our home. Our people gladly give their lives for her sake. How can I stand idly by. † – Xiao Qiao (Red Cliff II, 2009)Many Western philosophers may not understand and argue that the Chinese philosophy of individualism emphasizes on one’s connection to external powers of authority rather than total independence and creativity. However the Chinese tradition is not about conforming each person’s ideas and sacrificing oneself for society, it â€Å"focuses on the individual as a vitally integrated element within a larger familial, social, politic al, and cosmic whole† (Internet Encyclopedia of Philosophy, Brindley). The core meaning of individualism is the thought of one’s self cultivation and the moral obligation to society and the importance of public service.This definition leads to the term junzi which simply means the ideal of becoming the â€Å"perfect man† who â€Å"combines the qualities of saint, scholar, and gentleman†. The two most prominent examples of a junzi in the film are Zhou Yu and Zhuge Liang. Zhou Yu’s forgiving nature allows him to achieve a greater good for his people when he chose to pardon his friend’s action of siding with Cao Cao. He did not choose to kill him when his childhood friend tried to convince him to surrender to Cao Cao but instead tolerated his friend’s disloyal character.On the other hand, Zhuge Liang is a good representation of a junzi as he uses his moral autonomy to help the people. Because he knows clearly what is right and wrong, he combines his intelligence with righteousness to convince others of accepting his strategies as an advisor. In conclusion, both having filial piety and being a junzi are two of the ways the early Chinese believe an individual can contribute back into society. In the film Red Cliff, the underlying moral of the story relates back to these two themes whether it is in the form of brotherhood, husband and wife or a leader and his subjects.The Relationship between Man and Nature The relationship between man and nature in classical Chinese philosophy can be characterized as the â€Å"relation of Heaven and man† or the fundamental concept of â€Å"tienren he yi† . The academic aim of Chinese thinkers was to educate the people on this philosophy. As quoted from Sima Qian stating the purpose of his work Records of the Grand Historian, â€Å"I want to hereby elucidate the relation of Heaven and man, to discern its historical development from Past to Present, and to state my disti nctive views. After the middle period of the Warring States, classical thinkers strongly emphasized the relation of Heaven and man. When Confucius speaks about the â€Å"Mandate of Heaven† and when Mozi talks about the â€Å"Will of Heaven†, they are ultimately referring to nature as Heaven being the supreme entity of the world, above all kings and all sources of power. However this philosophy was divided into two sides, one highlighting the unity between man and nature and the other putting much emphasis on the separation of the two.Nevertheless, the doctrines supporting the unity of man and nature was more influential and accepted more widely as the thought of stressing on the separation of the two was only held by a minority. Therefore it can be assumed that most Chinese philosophers place high social values on peace and harmony and the idea of â€Å"unity of nature and man†. To the Chinese, the relationship between humans and nature was regarded as reciproca ls. Heaven, earth, and man represented a single unity governed by the cosmic law or dao.Mencius, the most famous of Confucius’ followers, thought of Heaven as the highest order in which even the emperor or â€Å"Son of Heaven† should obey. Reinstating the idea of the hierarchy of respect Mencius states that †¦when the personal life is cultivated, the family will be regulated; when the family is regulated, the state will be in order; and when the state is in order, there will be peace throughout the world. From the Son of Heaven down to the common people, all must regard the cultivation of personal life as the root or foundation.Mencius believed that a person’s moral self is the basis of having a harmonized society. And in order for a leader to earn the respect and support of his subjects, he must first respect the Heavens. Since humans are an integral part of nature, man should also obey the laws of nature. According the Mencius, human nature is given by He aven, therefore the two are interconnected. In Confucian thinking, the meaning of Heaven or nature has a variety of aspects, including the sky, weather, the natural order, and also a moral order. One of Confucius’ disciples Xunzi quotes â€Å"tian as a atural order, operating according to unchanging principles, not intervening in extraordinary ways in human affair but, rather, providing the context within which all living things exist† (Sources of Chinese Tradition, p. 170). Other Confucians also adopted the idea of oneness of Heaven and man. â€Å"All things exist together, and they do not harm each other; all ways exist together, and they do not come into conflict† – Zhongyong (Doctrine of the Mean). In the film Red Cliff, an example of acting out against nature or Heaven can be seen from Cao Cao’s perception of the war.When Cao Cao tells Zhou Yu that he cannot believe he lost the war because of the wind, Zhou Yu replies him, â€Å"Because you d on’t understand the Will of Heaven. † The meaning of this phrase can be seen as having two connotations. The first, because Cao Cao did not understand the patterns of the weather, he was unable to predict the time when the wind was going to change directions. The second significance has a more profound undertone in which Zhou Yu means that Cao Cao did not recognize the natural order wherein society should follow under harmonized principles that the Heavens intended (tian yi, . Because Cao Cao always thought he was responsible for bringing together all the states as an order of the Emperor, he could not see past his own greed and ambitions. He perceived the war as child’s play and disrupts peace in the country to achieve his goal of total dominance. His belief of unifying the states contradicts the early philosophers’ notions of all things existing in harmony and having self cultivation and moral order as the true â€Å"Will of Heaven†. ConclusionIn conclusion, one can see that classical Chinese philosophers developed ideas that are rarely seen in Western philosophies. The Chinese philosophies characterize how fundamental they perceive moral principles and self cultivation as the basis of society. Essentially, these notions relate to the promotion of human relations towards a harmonious society through its inclusiveness of Heaven, Earth, and Human order. Reference List De, Bary William Theodore, Irene Bloom, Wing-tsit Chan, Joseph Adler, and Richard John Lufrano.Sources of Chinese Tradition. New York: Columbia UP, 1999. Print Hagop Sarkissian. â€Å"Individualism in Early China: Human Agency and the Self in Thought and Politics (review). † Philosophy East and West 62. 3 (2012): 408-410. Project MUSE. Web. 17 Oct. 2012. . Red Cliff Chi Bi. Magnolia Home Entertainment, 2008. DVD â€Å"Theories Concerning Man and Nature in Classical Chinese Philosophy. † CHAPTER I. N. p. , n. d. Web. 13 Oct. 2012. .

Christians Seek Happiness And Fulfillment From A Higher Power

Christians seek happiness and fulfillment from a higher power, a purpose that others cannot see or touch. They have faith that God will reward them in heaven for their commitment and unselfish efforts to help others in need. From the very beginning, Christians have never really fit into the normal ways of the world. Many people believe Christians think, say and do things that are very foreign to cultural norms. This should not be surprising as they are expected to stand not just for one’s self, but to be believed in a higher power, to obey the creator and to show love, patience and kindness to others. Once a believer enters the Christian religion and starts to practice the traditions, they should stop acting like the rest of the world. They are called to a change of lifestyle and a life on mission. This belief forces Christians to think, speak and act differently than non-believers. 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