Determination of Dissolved Oxygen In a Water Essay Example for Free

Determination of Dissolved Oxygen In a Water Essay INTRODUCTION In an alkaline solution, dissolved oxygen will oxidize manganese(II) to the trivalent state. 8OH-(aq) + 4Mn2+(aq) + 2H2O(l) ï ¼ Ã¯ ¼ Ã¯ ¼Å¾ 4Mn(OH)3(s) The analysis is completed by titrating the iodine produced from potassium iodide by manganese(III) hydroxide. 2Mn(OH)3(s) + 2I-(aq) + 6 H+(aq) ï ¼ Ã¯ ¼ Ã¯ ¼Å¾ 2Mn2+(aq) + I2(aq) + 6H2O(l) Sodium thiosulphate is used as the titrant. Success of the method is critically dependent upon the manner in which the sample is manipulated. At all stages, every method must be made to assure that oxygen is neither introduced to nor lost from the sample. Furthermore, the sample must be free of any solutes that will oxidize iodide or reduce iodine. Chemicals: Manganese(II) sulphate solution – prepared by dissolving 48 g of MnSO4.4H2O in water to five 100 cm3 solution; alkaline potassium iodide solution—prepared by dissolving 15 g of KI in about 25 cm3 of water, adding 66 cm3 of 50% NaOH, and diluting to 100 cm3; concentrated sulphuriv(VI) acid; 0.0125 M sodium thiosulphate solution; starch solution (freshly prepared). Apparatus: 250 cm3 volumetric flask, 250 cm3 conical flask, measuring cylinders, titration apparatus, magnetic stirrer Procedure: 1.Use a 250 cm3 volumetric flask to collect water sample. Fill the flask completely with water without trapping any air bubbles. 2.Add 1 cm3 of manganese(II) sulphate solution to the sample using a pipette. Discharge the solution well below the surface (some overflow will occur). 3.Similarity introduce 1 cm3 of alkaline potassium iodide solution. Be sure that no air becomes entrapped. Invert the bottle to distribute the precipitate uniformly. [Hazard Warning: Care should be taken to avoid exposure to any overflow, as the solution is quite alkaline.] 4.When the precipitate has  settled at least 3 cm below the stopper, introduce 1 cm3 of concentrated sulphuric acid well below the surface. Replace the stopper and carefully mix until the precipitate disappears. A magnetic stirrer is helpful here. 5.Allow the mixture to stand for 5 minutes and then withdraw 100cm3 of the acidified sample into a 250 cm3 conical flask. 6.Titrate with 0.0125M sodium thiosulphate until the iodine colour bec omes faint. Then add 1 cm3 of starch solution and continue adding the thiosulphate solution until the blue colour disappears. 7.Record the volume of thiosulphate solution used and calculate the dissolved oxygen content in the sample in mg dm-3. Remarks 1.If the water sample has a low DO value, it is recommended to withdraw 200 cm3 of the acidified sample into a 500 cm3 flask for the titration describe in step 5. 2.This experiment can be further developed into a project to study the extent of water pollution. (a)The water sample under investigation is divided into two portions. One portion of the sample is immediately analysed for dissolving oxygen using the Winkler method. The other portion is stored in the dark for five days. (b)Repeat the analysis with the water sample that has been stored in the dark for five days. The difference between the two measurements is the five-day biochemical oxygen demand (BOD5), measured in mg dm-3.

Mastery by Robert Greene: The Steps to Mastery Essay -- creative task,

I am pursuing a Masters degree in Instructional Design and Technology. With this degree, I hope to gain the skills to help revolutionize education with the use of technology. In 1907 Maria Montessori, embarked on such a journey (American Montessori Society, 2013). She was invited to open a center for children living in the poor, inner-city of Rome (American Montessori Society, 2013). While working there, Maria began using approaches to educate the children that would find great success and become world-renown. Because Maria Montessori revolutionized education in a way that I hope to do, I chose her as the focus of my hero in Mastery research paper. In chapter five of his book, Mastery, Robert Greene (2012) outlines the way to find mastery. The first step to mastery is The Creative Path (Greene, 2012 p. 179). Greene states that becoming a master will not occur if you are easily swayed by setbacks or desire a life full of ease and comfort (Green, 2012 p. 179). When pursuing a creative endeavor one must pursue it with their whole being. Maria Montessori was able to achieve mastery despite the obstacles she faced. Montessori grew up in Italy and from an early age showed an interest in reading and academics, which differed from most females of her time (Adams, 1969, p. 49). Maria attended the University of Rome, much to the disdain of her father and the university, and in 1896 she became the first woman in Italy to graduate with a Doctor of Medicine degree. (Adams, 1969, p. 49; Solan, H. A. (2007) p. 61). Like a true master, Montessori did not stop pursuing knowledge in her field. Shortly after graduation she was introduced to a na rrower field of medicine and in 1897 returned to the University of Rome to study pedagogy and education... ...hrough: their development of The Current – his through his experiments with amputee patients and hers through her experiments educating children with disabilities; their study of anomalies – his study of phantom limb syndrome and her study of the education process for the mentally and physically disabled; and they both searched for the great yield – him through evidence of his simple experiments and her through evidence from the Casa dei Bambini. Works Cited Adams, Anne H. (1969, September). Maria montessori: a vignette. Education. p. 49. American Montessori Society. (2013) Maria montessori (biography of). Retrieved from http://amshq.org/Montessori-Education/History-of-Montessori-Education/Biography-of-Maria-Montessori Greene, R. (2012). Mastery. New York: Viking. Solan, H. A. (2007). Maria montessori: a biography. Optometry & Vision Development, 38(2), 61.

In Tess of the DUrbervilles, how does Hardy present Tess Essay

In Hardy’s tragic novel, nothing is as clear as it seems. Although Alec D’Urberville was the ostensible instigator of the protagonist Tess Durbeyfield’s downfall, it must be argued that Angel Clare plays just as a significant role in her destruction. Initial contemporary readings saw Tess and Angel’s relationship as doomed by Tess’ past, while more modern interpretations point to Angel’s decision to leave for the failure of the marriage. Throughout the novel, Hardy makes great use of foreshadowing in order to emphasise how the numerous tragedies in his protagonist’s life cumulate in disaster. This has never been more apparent than with Tess and Angel: as a keystone of the novel, their relationship is haunted by the spectre of the past all the way through. By introducing Angel almost as soon as he establishes Tess’ character, Hardy makes it clear from the outset that this relationship will be more significant than any other.. It is evident that Angel and Tess will fall in love, but what is even more arresting is Angel’s initial and lasting impression that Tess is the epitome of purity and maidenhood. Hardy starkly emphasises Tess’ virginal aspects through compound nominal phrases such as â€Å"white shape† and â€Å"pretty maiden†, creating the lasting image of her as a perfect woman. However, when Angel leaves and â€Å"dismisses the subject from his mind†, Hardy at once shows Angel’s objectification of Tess and how easily he can put aside her hurt, hinting at their relationship to come. Even once Angel knows who Tess is, his initial impression of her as a â€Å"fresh and virginal daughter of Nature† does not change but only becomes deeper embedded in his and the reader’s subconscious, painting a cruel contrast between his expectations and the real knowledge of Tess’ past. As soon as Angel and Tess meet again at the idyllic Talbothay’s Dairy, Hardy introduces the severe contrast between Tess’ simple nature and Angel’s intellectual presence, foreshadowing more than ever that once Tess’ past comes to light, the relationship is doomed. When Angel first notices Tess at the breakfast table, Hardy subtly hints about his idiosyncratic tendency to see what he wants to see to the reader, saying that he â€Å"was ever in the habit of neglecting the particulars of an outward scene for the general impression†. This may seem to be incongruous with Angel’s introspective and thoughtful character, but when considered alongside his behaviour towards Tess, it fits perfectly. The use of the adverb â€Å"ever† suggests that Angel is fixed and unswerving in his beliefs and principles. In particular, Hardy is setting the scene for Angel’s refusal to take into account the mitigating circumstances of Tess’ rape, as he only sees the gross magnitude of the sin that has been committed. He refuses to entertain the notion that her past is similar to his, gasping â€Å"My God- how can forgiveness meet such a grotesque- prestigidation as that! † Hardy’s use of the adjective â€Å"grotesque† indicates how Angel simply cannot equate such a brutal act as rape with the innocent Tess, and it is anger at this, rather than at Tess herself, which causes his outburst. Additionally, Angel is idealistic in his morals, â€Å"imaginative to impracticability† as Hardy later scorns him, and this early quotation shows how Angel refuses to compromise his high ideals for anything, even his love for Tess. He takes advantage of her unshakeable belief in his views and asks her to â€Å"Think of years to come†¦ and this past matter getting known- for it must be known†, striking fear into her honest heart and preventing her from using her feminine charms as a tool of persuasion. Tess genuinely believes him and does not think to suggest emigrating: her loyalty to him is such that she does not question his decision. Early on in Angel and Tess’ relationship, Hardy describes Tess’ unhappiness at her apparent want of intellectual capability compared to Angel, whom she sees as â€Å"an intelligence rather than a man†. Straightaway, Tess’ assumed inferiority is introduced, highlighting the insurmountable gap in the backgrounds of the two characters. Hardy even points out that during Angel’s initial reaction to Tess’ history, he still felt enough of a â€Å"back current of sympathy through which a woman of the world might have conquered him†, but she takes his emotional confusion as a final judgement, simply because she continues to see him as so superior to her. With the phrase â€Å"woman of the world†, Hardy brings attention to Tess’ pitiful lack of experience concerning men and relationships: he highlights how submissive Tess is that she will not attempt to change Angel’s mind, but also how pure and innocent she remains, that she will not use â€Å"her exceptional physical nature† in order to convince him to stay. However, through the use of the abstract noun â€Å"current†, the novelist implies that Angel’s emotions are transient and ever-shifting, portraying him as unreliable and untrustworthy. Angel’s idealism continues to be an important factor of the developing romance, creating the impression that the whole relationship is a fai ade. During the idyllic early morning meetings, Hardy illustrates a hazy new transitional world â€Å"in that strange and solemn interval, the twilight of the morning† to mirror Angel’s rose-tinted and not entirely clear vision of Tess. The author continually uses a semantic field of religious references to illustrate the significance of certain moments. For instance, Hardy describes â€Å"a feeling of isolation, as if they were Adam and Eve†, which not only confers heroic status on them, but creates an ominous sense that Tess’ past will eventually catch up with them and drive them from the lush, fertile Eden that is not only Talbothay’s Dairy, but the bubble of idealism in which the lovers are living. While Angel may be raised to â€Å"godlike† status while Tess is referred to as â€Å"the Magdalen†, supporting Tess’ idolatry of him, they cannot escape the third presence in their relationship. In one of Hardy’s most sensual descriptions of Tess, he describes â€Å"the red interior of her mouth† and compares it to a snake’s. The sensuality of the colour red and the snake both reference Alec D’Urberville, who is consistently given Satanic attributes such as â€Å"animalism† and â€Å"Paganism† as well as possessing â€Å"black angularities† in both appearance and personality, here symbolising the temptation that drove both Adam and Eve from Eden. Hardy cleverly employs the religious lexis: owing to his contempt of traditional, â€Å"quaint and curious† religion (which is divested in Angel and Tess’ rebellious views), his use of instantly recognisable Biblical features makes the point that Angel and Tess’ doomed relationship is simply a sad story that has been played out many times at some level over the centuries. Due to his portrayal of Tess as pure and guiltless, Hardy uses religion to emphasise how women like Tess have been in similar predicaments ever since Eve. It also gives a greater gravity to Tess and Angel’s romance, as the reader knows that it is finite. Hardy continues to expose faults in Angel’s character, namely his hypocrisy and ability to change his mind easily, showing how the relationship only leads to disaster. During their courtship he staunchly argues that her low position as a milkmaid does not and will not deter him- on the contrary, Angel insists he needs a wife â€Å"who knows all about the management of farms† and Tess, therefore, is better suited to him than the Mercy Chant. However, during the passionate argument when Tess follows Angel out of the house after her confession, Angel states firmly that he and Tess belong to â€Å"different societies† and compares her to â€Å"an unapprehending peasant woman† who has never experienced any form of society. This example is not unique: Hardy portrays Angel as eager to seize on an idea and find any evidence to fit it, regardless of previous beliefs: for instance, his ever-changing opinion of â€Å"old families† which only depends on his attitude to Tess at the time. One of the most obvious events that foreshadows the ending of the novel is Angel’s somnambulation. Hardy wrote this scene to symbolise all of Angel’s conflicting emotion and Tess’ self-destructive nature. The outpouring of Angel’s love for his â€Å"dearest, darling Tess! So sweet, so good, so true! â€Å", which he kept so carefully hidden during the day, hints at yet another change of mind on his part later on in the novel, while his exclamation â€Å"‘dead, dead! ‘† signifies not only how Tess is morally dead to him, but how he feels his actions have killed the spirit and love within his â€Å"‘poor, poor Tess'†. Even though Tess suspects multiple times that Angel’s actions could lead to her death, either intentionally or accidentally, â€Å"self-solicitude was near extinction in her†, linking to how she remains placid and uncomplaining even throughout temptation and harsh conditions at Flintcombe-Ash. When Angel â€Å"carefully laid† her in the open coffin, Hardy is symbolising that due to Tess’ devotion to Angel, she will allow herself to be led to her death, arguably the greatest moment of symbolism in the novel. In Tess of the D’Urbervilles, Hardy as the omniscient narrator remains firmly on the side of his protagonist: she is the vehicle for him to express his contempt of the traditionally misogynistic values so strongly upheld by Victorian society. Although Angel professes to reject these conventions, he ultimately submits to them, thus creating an even greater divide between the two lovers. In her final hours, Tess herself states that her happiness with Angel â€Å"could not have lasted† and that it was better that she would be gone, fulfilling Hardy’s portrayal of a love that was sincere, almost ethereal, but lavished on a fallible, human man, and therefore inevitably doomed to fail.

Using Broach and Brooch Correctly

The words broach and brooch are homophones: theyre pronounced the same but have different meanings.   Definitions As a verb, broach means to pierce, break into, or open up. The verb broach also means to introduce (a topic) for discussion or make (something) known for the first time. As a noun, broach refers to a tapered cutting tool or a hole made by such a tool. The noun brooch refers to an ornamental pin thats usually worn at the neck. The two words are pronounced alike: brÃ… ch (rhymes with coach). Examples The best time to broach the topic of a raise is on a slow day at work.The broach has a series of cutting teeth along the axis of the tool.Humphrey Pump plunged down again into the sunken nest and began to  broach the cask  of rum in his own secret style, saying We can get something else somehow tomorrow. For tonight we can eat cheese and drink rum, especially as theres water on tap, so to speak.(G.K. Chesterton,  The Flying Inn, 1914)The princess wore a diamond brooch the size of a silver dollar. Usage Notes A brooch, a decorative pin or clip, is nothing like a broach. But since theyre often pronounced alike, and because ignorance never rests, some dictionaries accept broach as an alternative spelling of brooch.(Jane Straus,  et al.,  The Blue Book of Grammar and Punctuation, 11th ed. Jossey-Bass, 2014)If you broach something, you are suggesting that it is a valid topic for possible further discussion. If you wear a brooch on your dress, you hope that it will attract attention because of its beauty, and therefore, of course, attract attention to you who are wearing the brooch.(David Rothwell, Dictionary of Homonyms. Wordsworth, 2007 ) Practice (a) Because Ms. Widmark said she was there on business, the lawyer felt he should _____ the matter of his fees. (b) Marie wore the emerald _____ that she had inherited from her grandmother. Answers Answers to Practice Exercises:  Broach and Brooch (a) Because Ms. Widmark said she was there on business, the lawyer felt he should  broach  the matter of his fees.(b) Marie wore the emerald  brooch  that she had inherited from her grandmother.