Sodium Hydroxide Essay Example for Free

Sodium Hydroxide Essay Research Question: When constant successive portions of Sodium Hydroxide are added to Acetic Acid; how do the changing amounts of Sodium hydroxide mixed with Acetic Acid in the conical flask affect the pKa of Acetic Acid? Background Research: A weak acid is defined as being an acid that does not donate all of its hydrogen ions in a solution (Neuss, 2007) A weak acid represented by HA will always be in equilibrium with its ions in an aqueous solution, for example: HA (aq) H+(aq) + A-(aq) The equilibrium constant will thus be given as products over reactants by: Ka is most commonly known as the acid dissociation constant. The pKa is just the pH of the Ka i.e. pKa = -logKa and is used as a quantitative measure the strength of a weak acid in solution. Acetic acid (CH3COOH) is a weak acid and Sodium Hydroxide (NaOH), on the other hand, is a strong base and reacts with Acetic acid (CH3COOH) to produce water (H2O) and a salt (NaCH3OO) as follows: CH3COOH + NaOH H2O + NaCH3OO A method called a Titration provides information about the behavior of acids through the pH scale. In a titration, base is gradually added until the acid reaches an endpoint or equivalence point. When the equivalence point is reached, the pH of the solution will change rapidly, because all the acid has reacted with the added base. A pH meter can be used to determine the pH of the acid throughout the titration, and can be used to determine the equivalence point. When carefully measured volumes of strong base are added to a solution of weak acid and the pH is noted, a graph can be drawn with pH on the y axis and the volume on the x axis. The graph is known as the Titration/pH curve and the theoretical pH curve of the neutralization reaction between Acetic acid and Sodium Hydroxide is provided below: Figure 1: Theoretical Titration curve of Acetic acid and Sodium Hydroxide. This picture was obtained through www.google.com/images/titrationcurve The flat portion of the titration curve before the end point (refer to figure 1) is called the buffer region. In this part of the pH scale, that the Acetic acid and Sodium hydroxide are both preset in significant concentrations and the solution resists changes in pH. In the middle of the buffer region lies the half equivalence point. Here the volume of base added is half that required to reach the equivalence point. We can determine the pKa or Ka of an acid by finding the pH when half way to the endpoint of the titration since pKa = -log Ka (refer to figure 1). A smaller Ka value suggests a larger pKa value. The larger the pKa value the weaker the acid. Base solution is added until the equivalence point is reached. Thus, to determine the pKa of Acetic acid, the amounts of base mixed with acid will vary, the pH will be measured at regular intervals which will ultimately allow the pKa to be determined. Hypothesis: In this experiment, the amount of Sodium Hydroxide released from the burette will never change. What changes, however, is how much base is in the conical flask. To begin with there will be no base but when 1cm3 of Sodium Hydroxide is added then there is 1mL of Sodium Hydroxide in the conical flask. Then when another 1 cm3 of Sodium Hydroxide is added there will be 2mL of Sodium Hydroxide in the conical flask. So what is changed is the amount of base in the conical flask and it is this amount of base that changes the pKa. Thus, I hypothesize that as the amount of Sodium Hydroxide increases, pH will gradually increase until it reaches the end point where there will be a sudden increase. Afterwards, the amount of base will overtake the Acetic acid and this would result in a plateau in the pH curve. Aspect 2 Defining Independent and Dependent Variables Table 1: Dependent and Independent Variables Independent The amount of base (Sodium hydroxide) mixed with acid. In other words, the volume of NaOH dropped into the acid is controlled but what is changed is the amount of base in the conical flask. (1 cm3 will always be followed with 1 cm3, there will be no change in how much you put in each time; what changes is how much acid there is in the beaker) Dependent The pH of the solution Controlling Variables Table 2: Variables and Methods of Control Type Variable Method of Control Controlled The volume of the Acetic acid will be controlled 20 cm3 of the Acetic acid will be measured out using a Mohr pipette and then carefully released into the conical flask The pressure under which the experiment is carried out. All experiments will be conducted standard laboratory conditions, which means at 1atm pressure The Temperature under which each experiment is conducted. All experiments will be conducted in the same room within quick succession. The amount of base added to conical flask each time Successive portions of 1 cm3 of NaOH will be added to the conical flask until it reaches the endpoint Human judgment errors The person conducting the experiment must read from the burette in which holds the NaOH. By using the same person for each experiment- the error of judgment will be kept constant. Aspect 3 Materials and Equipment List (enough for 1 titration including the rough titration) 1 x 50 +/- 0.05 cm3 Burette 1 x Burette Stand and clamp 1 x funnel 1 x 100 +/-0.050 cm3 Conical flask GLX pH probe 1L Distilled Water 1 x 20 +/- 0.020 cm3 Mohr Pipette 50 cm3 of Acetic Acid concentration of approximately 0.1mol dm -3 100 cm3 Sodium Hydroxide solution 0. 1mol dm -3 Safety Glasses White Paper Graph Paper Pen Pencil, for drawing the Graph Rubber Gloves (in case of glass breakage) 1 x White tile 1 x Standard Bulb 50 cm3 bottle of Phenolphthalein indicator (only 4 drops are required) Paper towels (for cleaning) Figure 2: Conical Flask Figure 3: Burette Figure 4: Mohr Pipette These pictures were all obtained from www.google.com/images General Method 1. Before commencing this experiment it was made sure that all involved in the experiment were wearing the safety goggles and a lab coat to avoid risk of injury (refer to table 3) 2. The Titration was set up as follows, with the clamp holding the burette and the funnel at the top of the burette. The conical flask should be placed on a white tile underneath the burette. The burette should be clamped so that its tip is within the conical flask but above the surface of the solution. Figure 5: Titration set-up 3. The burette was then rinsed with distilled water to ensure that it is clean and to avoid errors 4. Usually experimenters cannot reach the top of the burette when its placed on a lab bench, so as a result, the burette and the burette stand were placed on the ground and Sodium Hydroxide was carefully poured to the first digit on the top of the burette (usually 0) via the funnel. The initial reading of the burette was then recorded in the results table, refer to table 3. Afterwards, the burette was returned to its original position on the top of the bench 5. The Mohr pipette was then checked for chips and cracks and was rinsed several times to ensure accurate volume measurements 6. Afterwards, the Mohr pipette was used to collect 20 cm3 of acid (Please refer to the Using Mohr pipette method) and the acid was then poured into the conical flask 7. Immediately following, the GLX pH probe, refer to GLX probe method, was adjusted and the head was placed in the acid, the pH of the initial acid was recorded in the results table, refer to table 3 8. 2 drops of Phenolphthalein was then added to the acid. The Phenolphthalein is an indicator which means it turns pink when base is added, an indication of endpoint would be that the liquid in the conical flask turns pink 9. To begin with, a rough Titration was be done to estimate the endpoint 10. In a rough Titration the tap was opened, and the base was simultaneously released into the conical flask until the liquid turned pink in which the tap was closed. When the liquid turned pink the final pH was recorded in the results table. Also record the final reading of the burette. The Rough Titration is only an indication and so should not be used in data analysis. 11. After the Rough Titration, the solution in the conical flask was discarded in the sink. Since the products were neutralized solutions of common salts they can safely be disposed of down the sink. 12. The conical flask was then washed with distilled water and 20 cm3 of Acetic acid was then poured into it via the Mohr pipette. And immediately following this, the GLX pH probe was placed inside the acid. Sodium Hydroxide was also then poured into the burette, using the method discussed in point 4, to top it up 13. The titration was then initiated, and successive portions of 1 cm3 of Sodium Hydroxide were added to the conical flask. After each addition, the burette and pH readings were obtained and recorded. If the person doing the experiment is right handed, then their right hand should be used to open and close the tap to allow Sodium Hydroxide to drip out and their left hand should be used to swirl the solutions in the conical flask. Swirling is important as the pH may drift until a completely homogenous solution is achieved. The same principle applies to left handers, except they would of course use their left hand instead of their right hand to release the NaOH. 14. The Titration was continued until the pH reached 12, the final burette reading was also recorded 15. This titration process (steps 11-14) was repeated another two times, allowing more reliable results. 16. After the Titration the benches were wiped down using paper towels, the solution was discarded in the sink and the glassware was placed in the designated container. Hands were washed before leaving the laboratory. 17. By the results gathered, a Titration curve can be drawn. The pH would simple be on the y axis while the volume of the base would be on the x axis. The pKa can be determined by finding the pH halfway to the endpoint of the Titration curve. GLX pH probe method: 1. The probe was first turned on and then pH probe section was plugged in at the top. 2. The pH probe section was then placed into the Acetic acid 3. Automatically, a pH reading appeared on the screen 4. When enough data was collected the recorded was stopped and the probe was unplugged 5. The GLX pH probe was then plugged into a laptop to export the data to the computers hard drive Using Mohr Pipette method: 1. The standard bulb was attached to the end of the pipette by carefully fitting the bulb at the end of the pipette 2. The pipette tip was then placed below the surface of the liquid and the bulb was squeezed to draw the liquid up. 3. The volume of the Acetic acid in the pipette was determined by reading the meniscus of the pipette 4. The pipette was then held above the conical flask, and the bulb was released to release all the liquid into the conical flask Table 3: The results table pH recorded Rough Titration Volume of Sodium Hydroxide added Amount of base in the conical flask (burette reading) 1st Trail 2nd Trail 3rd Trial Initial burette reading (cm3) 1 cm3 1 cm3 Final burette reading (cm3) 1cm3 2 cm3 Volume of Titration (cm3) 1cm3 3 cm3 1 cm3 4 cm3 1cm3 5 cm3 Note: The purple shaded region is the rough Titration. The volume of Sodium Hydroxide added each time will always be 1 cm3 but the Amount of base in the conical flask will change. Also, the patterns in this table should be continued until the Amount of base in the conical flask is at least 30 cm3. The pH will be recorded via the GLX data probe. Safety Precautions Table 4 : The risks involved in the experiment and safety precautions to reduce the risks Name Risk Precautions Sodium Hydroxide Can cause serious burns, however the 0.1 concentration of Sodium Hydroxide cannot cause harmful burns unless excessive amounts of it are poured on the skin. Harmful by ingestion and skin contact. Safety Glasses are needed to reduce the risk of injury if a spill occurs. Avoid skin contact with Sodium Hydroxide as well as ingestion. Acetic acid Causes burns, however the 0.1 concentration of Acetic acid cannot cause harmful burns unless excessive amounts of it are poured on the skin. Harmful by ingestion and skin contact. Safety Glasses should be worn the entire time to reduce the risk of injury. Gloves and Lab coat should be worn to avoid skin irritation. Avoid skin contact with Acetic acid. Glass wear Breakages can cause cuts and serious chemical spills Wearing rubber gloves make sure that all broken glass is disposed of appropriately. The burette should also be handled very carefully as it is very fragile. Spillage of Sodium Hydroxide or Acetic acid Can cause serious burns Wash any spills copiously with water BIBLIOGRAPHY * Volumetric analysis. 4 Feb 2009 http://www.uwplatt.edu/chemep/chem/chemscape/LABDOCS/CATOFP/measurea/volume/pipet/pipet4.htm. * Acid-base titrations. Wikipedia. 4 Feb 2009 http://en.wikipedia.org/wiki/Acid-base_titration. * pKa and LogP Measurements. 4 Feb 2009 http://www.raell.demon.co.uk/chem/logp/logppka.htm. * pKa of a weak acid. 4 Feb 2009 http://209.85.173.132/search?q=cache:E6yRz3RiHlwJ:www.profpaz.com/Files/chem102/Exp_10.pdf+%22volume+at+equivalence+point%22hl=enct=clnkcd=1gl=au. * Neuss, Geoffrey. Chemistry . London: Oxford, 2007. * Neuss, Geoffrey. Chemistry For the IB diploma. London: Oxford, 2007. Cited using http://citationmachine.net/index2.php

Biography of Michelangelo Essay example -- Michelangelo Artists Painte

Biography of Michelangelo The second of five brothers, Michelangelo was born on March 6, 1475, at Caprese, in Tuscany, to Ludovico di Leonardo di Buonarotto Simoni and Francesca Neri. The same day, his father noted down: "Today March 6, 1475, a child of the male sex has been born to me and I have named him Michelangelo. He was born on Monday between 4 and 5 in the morning, at Caprese, where I am the Podestà  ." Although born in the small village of Caprese, Michelangelo always considered himself a "son of Florence," as did his father, "a Citizen of Florence." His Childhood and Youth Buonarroti's mother, Francesca Neri, was too sick and frail to nurse Michelangelo, so he was placed with a wet nurse, in a family of stone cutters, where he, "sucked in the craft of hammer and chisel with my foster mother's milk. When I told my father that I wish to be an artist, he flew into a rage, 'artists are laborers, no better than shoemakers." Buonarroti's mother died young, when the child was only six years old. But even before then, Michelangelo's childhood had been grim and lacking in affection, and he was always to retain a taciturn disposition. Touchy and quick to respond with fierce words, he tended to keep to himself, out of shyness according to some but also, according to others, a lack of trust in his fellows. His father soon recognized the boy's intelligence and "anxious for him to learn his letters, sent him to the school of a master, Francesco Galeota from Urbino, who in that time taught grammar." While he studied the principles of Latin, Michelangelo made friends with a student, Francesco Granacci six years older than him, who was learning the art of painting in Ghirlandaio's studio and who encouraged Michelangelo to follow his own artistic vocation. Early Life in Florence. Michelangelo's father, now a minor Florentine official with connections to the ruling Medici family, placed his 13-year-old son in the workshop of the painter Domenico Ghirlandaio. After about one year, Michelangelo went on to study at the sculpture school in the Medici gardens and shortly thereafter was invited into the household of Lorenzo de' Medici *http://www.thais.it/scultura/sch00073.htm*, the Magnificent. There he had an opportunity to converse with the younger Medici, two of whom later became popes (Leo X and Clement VII). He also became acquainted with such humanis... ...e." Michelangelo's Achievements During his long lifetime, Michelangelo was an intimate of princes and popes, from Lorenzo de' Medici to Leo X, Clement VIII, and Pius III (1439-1503), as well as cardinals, painters, and poets. Neither easy to get along with nor easy to understand, he expressed his view of himself and the world even more directly in his poetry *http://scriptorium.lib.duke.edu/mazzoni/exhibit/treasures/B56.html* than in the other arts. Much of his verse deals with art and the hardships he underwent, or with Neoplatonic philosophy and personal relationships. The great Renaissance poet Ludovico Ariosto wrote succinctly of this famous artist: "Michelangelo was widely awarded the epithet 'divine' because of his extraordinary accomplishments". Two generations of Italian painters and sculptors were impressed by his treatment of the human figure: Raphael, Annabale Carracci, Pontormo, Rosso Fiorention, Sebastiano del Piombo, and Titian. His dome for St. Peter's became the symbol of authority, as well as the m odel, for domes all over the Western world; the majority of state capitol buildings in the U.S., as well as the Capitol in Washington, D.C., are derived from it.

1984 – Technology in Todays Soceity

Not many people are fans of being excessively supervised and observed. From an 11 year old boy being observed in the park by his grandparents, to a student sitting in class being observed by the teacher during examination. Knowing that you are constantly under surveillance can be very intimidating. Right through history, the intensity of government regulations have altered from low down to sky-scraping. The novel 1984, written by George Orwell consistent of a very dictatorial government. In this fictional commentary novel, George Orwell predicts the future where technology and the power given to the government will reduce privacy in everyone’s day to day life. Today’s society is majorly impacted by the rapid development of technology; in the novel George Orwell had used technology as an example of lack of privacy. To begin with, our advanced technology has reached such an extent that it is very straightforward for the government to figure out everything about us from our past including, our previous vacation, were we live, where we attended school or even last time we made a purchase through our debit or credit. To gain access into a person’s life the government has issued every citizen a social insurance number, this card contains a person’s entire record of everything that they have done in the country. This is related to what George Orwell had expressed in his novel, the government in the novel is being referred to the big brother. In the novel the big brother kept watch over every step that was done by the humans, there was even a sign which said â€Å"big brother is watching you,† this is the same as our government now since most things we do are being watched or even listened to. Another example of this would be the use of telescreens in the novel. The telescreens previewed everybody’s room in the building; therefore if any movement or discussion going on will not be private, â€Å"Any sound Winston made, above the level of a very low whisper, would be picked up by it†. This is now similar to today’s surveillance cameras; although this novel was written in 1948 the first surveillance camera had been invented in 1965. Since then the world had become more advanced than ever before. Cameras are now put up almost everywhere in; business offices, convenience store, apartment buildings, intersections, even all age schools. In the novel the author essentially points out that the future will hold no privacy and telescreens. phone calls, emails, texting are examples of telescreens since they can be accessed by the government authorities anytime. In conclusion, the novel 1984, is a fiction although what George Orwell tried illustrating was us humans are going head over heel with technology which is giving the government power. Some events that occurred in his novel have actually accrued and while he was writing this novel it was all a prediction for the future because some things he mentioned did not exist in that time period.

Assimilation of Jews in the Interwar Period - 1374 Words

During the interwar period of the twentieth century, Jewish immigrants and American born Jews faced increasing ant-Semitism and discrimination. The external pressure of anti-Semitism and discrimination led to many Jews facing internal anxieties and conflicts about being Jewish and fitting into American society. Assimilation during this period meant fitting into the white gentile majority’s standard of appearance, mannerisms, and middle class ideals. Common stereotypical images from the time depict Jews with large noses and curly hair, women were often portrayed as dominant over their Jewish husbands, and Jews were often seen as manipulative, controlling, and money grubbing. Jews’ limited social acceptance came on by completely abandoning†¦show more content†¦Internal Jewish anxieties and struggles also made assimilation impossible. Lewisohn’s second reason explaining Jews cannot assimilate is because of their ancestral past. Jews â€Å"are a people† and â€Å"cannot shake off the impress of experience of seventy generations.† This Jewish past prevents Jews from assimilating because they cannot stop being Jewish, and even if one tries to forget or deny their Jewishness his past makes it impossible. The past is so imbedded â€Å"in his essential character. . . as well as of all his actions he remains a Jew.†6 Howe, like Lewisohn, also acknowledges the internal difficulties of assimilation. 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