Complexometric Determination of Water Hardnesss Essay Example for Free

Complexometric Determination of Water Hardnesss Essay Introduction/Background: This lab was about determining water hardness. Water hardness is the amount of metal ions in the water. The most common found ion in the water is calcium ions and typically with a charge of +2. Water hardness plays a big significance in our daily life because to many metal ions in our drinking water can have adverse effects on our body. You can measure the water hardness by EDTA titrations. EDTA is a disodium salt that stands for ethylenediaminetetraacetic acid and it is a chelating agent. Chelation is the process of a ligand forms a complex with a metal ion. Eriochrome Black T is an indicator you add to the water sample that will turn the water pink if metal ions exist. Through the process of titration, carefully adding EDTA to the water sample with the Eriochrome Black T will cause a chemical reaction to occur, slowly changing the water color from pink to violet and then violet to a light blue which will be the end of the chemical reaction. Once the titration is complete you can calculate your water hardness. Above in the formula V represents the actual delivered volume of Na2EDTA solution and M is your actual molarity. Procedures: Start by preparing 500mL of 0.004 disodium EDTA solution. This is what will be added to the buret. Next take a 250-mL Erlenmeyer flask and add 10.00mL of standardized calcium and 30mL of deionized water. Place a magnetic stir-bar in the flask and set on top of a piece of white paper on a magnetic stirrer. After place 3mL of ammonia/ammonium chloride buffer (pH10) inside the flask and let it stir for thirty seconds. Lastly add four drops of Eriochrome Black T indicator to the solution which will turn it a pink color. Begin titration and watch as the color changes from pink to violet and then violet to a light blue color. Record the data when the color turns a light blue and repeat the process two more times. Fill the buret with the same 500mL of 0.004 disodium EDTA solution. Take 25.00mL of an unknown water sample and add it to a 250mL Erlenmeyer flask. Mix in 20mL of deionized water. Set a magnetic stir-bar inside the solution and place on the magnetic stirrer. Next add 3mL of ammonia/ammonium chloride buffer (pH10). After thirty seconds of stirring add four drops of the Eriochrome Back T indicator and watch as the solution turns pink. Begin your titration by slowly adding small droplets of the 0.004 disodium EDTA solution. The color will slowly change to a violet color and then to a blue color which will be the stopping point. Record the data and repeat two more times. With the data collected calculates the hardness of each sample, then the average water hardness of all three samples, and lastly the precision of each trial. Compare your data to the expected range of a local cities water hardness. Results and Discussion: The first three titrations involved the known Calcium stock, titration 1 used 22.91ml of Na2EDTA solution before the titration complete. The second Titration used 21.91ml while the third and final used 21.55ml of solution. During the procedure a 250ml Erlenmeyer flask was used as well as a 50ml burette, the buret was filled with our Na2EDTA solution while the flask was filled with 30ml of DI water, 3ml of ammonia, and 4 drops of an indicator, in this case Eriochrome Black T. Experimental error was calculated by taking the sum of all absolute deviations/3 than divided by the mean concentration of Na2EDTA, in this case the mean concentration was .00452M, and lastly, multiplied by 1000 to get the answer in PPT. Table 1 below shows the readings of both solutions before and after titration. The mean concentration of these titrations is 0.00452, This figure was used to find the estimated precision which came out to 23.270% off of 100% meaning the experiment was 76.73% accurate. Finally the volume of the unknown was calculated to find the ppm for each titration and the mean of all three titrations was used to find the estimated precision of the unknown in ppm. The mean in ppm for the unknown came to 212ppm, this number was plugged into the equation for estimated precision which is the sum of all absolute value deviations/ number of trials, all of which is divide by the mean and multiplied by 1000ppt. The final figure came out to 25.2% off of 100% meaning that the experiment was 74.8% accurate. Conclusion: In conclusion the water hardness of a solution can be found by titrating a known solution containing metal ions and using a chelating agent such as EDTA to determine the impurities of each of the water samples. Also, using the data collected from each titration the concentration and mean can be found from each titration and used to determine the water hardness in ppm. The estimated precision of this experiment can be found by running multiple titrations on the same sample more than one time. The results obtained in this experiment include a mean concentration for the Calcium stock of .00452M, and an estimated precision of 76.73% and the average water hardness was 400.39ppm. The estimated precision for the unknown was 74.8% and an average water hardness of 204ppm. In this experiment 500ml of a known solution EDTA was prepared; a 10ml pipet was used to transfer a standard calcium ion stock solution into a 250ml Erlenmeyer flask. 30ml of DI water was added to the flask and the contents were than stirred using a magnetic stirrer and stirring rod. 3ml of Ammonia was added to the flask mixed for a few seconds underneath the fume hood and 4 drops of an indicator was added, in this case Eriochrome Black T. The contents of the flask were stirred for thirty seconds before titration began, as the titration progressed, the color changed from pink to violet and finally to a sky blue color indicating that the titration was complete. This process was completed with minor changes for the Unknown #141, 25ml of the unknown was placed in the flask and 20ml of Di water was used rather than 30ml, the rest of the titration however, used the same steps as above. Work Cited Klenck, Thomas. How It Works: Water Softener. Popular Mechanics 1 Aug. 1998: n. pag. Web. 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Bermuda Triangle :: Devils Triangle Paranormal

Bermuda Triangle, region of the western Atlantic Ocean that has become associated in the popular imagination with mysterious maritime disasters. Also known as the Devil's Triangle, the triangle-shaped area covers about 1,140,000 sq km (about 440,000 sq mi) between the island of Bermuda, the coast of southern Florida, and Puerto Rico. The sinister reputation of the Bermuda Triangle may be traceable to reports made in the late 15th century by navigator Christopher Columbus concerning the Sargasso Sea, in which floating masses of gulfweed were regarded as uncanny and perilous by early sailors, others date the notoriety of the area to the mid-19th century, when a number of reports were made of unexplained disappearances and mysteriously abandoned ships. The earliest recorded disappearance of a United States vessel in the area occurred in March 1918, when the USS Cyclops vanished. The incident that consolidated the reputation of the Bermuda Triangle was the disappearance in December 1945 of Flight 19, a training squadron of five U.S. Navy torpedo bombers. The squadron left Fort Lauderdale, Florida, with 14 crewmen and disappeared after radioing a series of distress messages, a seaplane sent in search of the squadron also disappeared. Aircraft that have disappeared in the area since this incident include a DC-3 carrying 27 passengers in 1948 and a C-124 Globemaster with 53 passengers in 1951. Among the ships that have disappeared was the tanker ship Marine Sulphur Queen, which vanished with 39 men aboard in 1963. Books, articles, and television broadcasts investigating the Bermuda Triangle emphasize that, in the case of most of the disappearances, the weather was favorable, the disappearances occurred in daylight after a sudden break in radio contact, and the vessels vanished without a trace. However, skeptics point out that many supposed mysteries result from careless or biased consideration of data. For example, some losses attributed to the Bermuda Triangle actually occurred outside the area of the triangle in inclement weather conditions or in darkness, and some can be traced to known mechanical problems or inadequate equipment. In the case of Flight 19, for example, the squadron commander was relatively inexperienced, a compass was faulty, the squadron failed to follow instructions, and the aircraft were operating under conditions of deteriorating weather and visibility and with a low fuel supply. Bermuda Triangle :: Devil's Triangle Paranormal Bermuda Triangle, region of the western Atlantic Ocean that has become associated in the popular imagination with mysterious maritime disasters. Also known as the Devil's Triangle, the triangle-shaped area covers about 1,140,000 sq km (about 440,000 sq mi) between the island of Bermuda, the coast of southern Florida, and Puerto Rico. The sinister reputation of the Bermuda Triangle may be traceable to reports made in the late 15th century by navigator Christopher Columbus concerning the Sargasso Sea, in which floating masses of gulfweed were regarded as uncanny and perilous by early sailors, others date the notoriety of the area to the mid-19th century, when a number of reports were made of unexplained disappearances and mysteriously abandoned ships. The earliest recorded disappearance of a United States vessel in the area occurred in March 1918, when the USS Cyclops vanished. The incident that consolidated the reputation of the Bermuda Triangle was the disappearance in December 1945 of Flight 19, a training squadron of five U.S. Navy torpedo bombers. The squadron left Fort Lauderdale, Florida, with 14 crewmen and disappeared after radioing a series of distress messages, a seaplane sent in search of the squadron also disappeared. Aircraft that have disappeared in the area since this incident include a DC-3 carrying 27 passengers in 1948 and a C-124 Globemaster with 53 passengers in 1951. Among the ships that have disappeared was the tanker ship Marine Sulphur Queen, which vanished with 39 men aboard in 1963. Books, articles, and television broadcasts investigating the Bermuda Triangle emphasize that, in the case of most of the disappearances, the weather was favorable, the disappearances occurred in daylight after a sudden break in radio contact, and the vessels vanished without a trace. However, skeptics point out that many supposed mysteries result from careless or biased consideration of data. For example, some losses attributed to the Bermuda Triangle actually occurred outside the area of the triangle in inclement weather conditions or in darkness, and some can be traced to known mechanical problems or inadequate equipment. In the case of Flight 19, for example, the squadron commander was relatively inexperienced, a compass was faulty, the squadron failed to follow instructions, and the aircraft were operating under conditions of deteriorating weather and visibility and with a low fuel supply.

No Class Pets!

Imagine that you are a soft and adorable Guiana pig that was born in a pet store from your captured parents. There, shoppers are banging on the cage window, trying to wake you up and see you running on your hamster wheel, and are screaming â€Å"Look! Cute piggy! † When you are purchased, you are transported to a tight, compact cage, believing thou will finally have some peace and quiet, but instead, every day you must endure even more despicable kindergà ¤rtners. Now, when you were busy imagining that you were that poor Guiana pig, you felt angry and mistreated, right?It s obvious that whether we should have classroom pets or not is a complex issue. While some may believe that class pets are beneficial In some ways, I feel that after researching both sides, It Is clear that there should not be any class pets. There are many disadvantages of having a classroom pet. They will waste too much money and demand a lot of attention. One disadvantage of having a class pet is that pet s aren't for free. In fact, they're very expensive! Guiana pigs may be small, but still have all the characteristics to be worthy of being called a â€Å"living thing.So if one died, its death cannot be called â€Å"smaller† than a human death. Humans cannot underestimate animals because of size. Therefore, they must be fed and given all basic necessities dally, and need to be raised properly. According to â€Å"Does a Guiana Pig Belong In the Classroom? â€Å": â€Å"A teacher must be very involved and dedicated to proper cavy care before the opposite becomes true. † A lack of these needs may result in a free, one- way trip into the void. Also, sick pets must visit the vet, like humans must go see the doctor. Pets die when they become very ill; we can't overestimate them either!But then again, pet go to vet = $$$$$ = not very fun! Reproduction Is also a problem. Andrea Milder-Slater states In the ‘Cons' section: â€Å"If you have a male and female hamster, r abbit, or fish, are you prepared for babies? Will you spay or neuter your larger pets? † Spay or neuter = Spend even more of your dear green paper and metal coins on more class pets! 6 pets= 6 times more resources= 6 times more money! While some may say that yes, there is one more solution, it is no better than spaying r neutering: let them have the babies, and then support them all. But if Bob and Gabrielle the Guiana pigs have 6 babies, uh Oh!Will the class even be able to afford to keep all 9 Guiana pigs alive? Or will they enjoy the prospect of using more money on this? In addition to large costs, class pets need a lot of attention. Can at least one pair of eyes be provided to watch the class pets at every second? They must be supervised at all times. This includes all breaks, weekends and holidays. What would the pets be doing when the students had summer vacation? They might starve to death because no one fed them while their owner was having a nice relaxing trip to Lass Vegas, gambling and sightseeing, totally forgetting about them?After all, if there actually was someone there, would any crimes have happened to the pets? Additionally, â€Å"Does a Guiana Pig Belong in the Classroom† tells us that a Guiana pig class pet â€Å"cannot simply be a decoration. A Guiana pig needs petting and interaction every single day. She also needs daily â€Å"floor time† to run around and explore. This includes weekends†¦ † Also, class pets must be safe at school overnight. You must take mom your class pet at these times to ensure their safety, since there might not be students when they are interacting with the class pet.Children might be too rough with it, or be frightened and drop it. These things might result in the class pet's demise. Numerous crimes have occurred to pets when nobody was with them. For example, â€Å"Say ‘No' to Class ‘Pets† states: â€Å"A snake was stolen from his classroom enclosure and cooked alive inside a school's microwave,† and â€Å"a lamb was stolen from a school agriculture building, spray-pained, duct-taped to the outside of the building, ND left alone overnight in freezing temperatures. † This means that those ‘pets' didn't receive the attention that they required.In addition, article â€Å"Say ‘No' to Class ‘Pets† says : â€Å"Once at a student's home, may classroom â€Å"pets† are ignored and deprived of both human contact and appropriate companions of their own species. Students who do not understand the responsibility and time that animal companions require may neglect to fill water bottles, provide food, or clean cages. † While some may think that bringing the pet home is very easy to do, the parents or families of the students, Hough, may find the pet extremely annoying or may refuse to accept or take care of them.After reviewing the provided sources, I believe that it is clear we shouldn't have class pet s. It is clear that banning them is the best option. In the future, we should really think about whether we should make another life suffer Just for students' â€Å"education† Really, it would Just be better not to have a class pet, as the famous class pet equation is: â€Å"Class pets = money = more money = much more money + make another life suffer! †

Evaluate the Relative Contribution of Nature and Nurture...

Evaluate the relative contribution of nature and nurture to human psychological functioning. Illustrate you answer with reference to material from at least two chapters from book 2. The debate concerning the contribution of nature and nurture to human psychological functioning is one of the longest running and most controversial within psychology. The question is what elements of human behaviour can be explained in terms of physical being and what can be explained in terms of social environment. Although this debate is relevant to many topics within psychology this essay will focus on two: language and sex and gender. Firstly it must be made clear what is meant by nature and nurture. Nature refers to the characteristics and abilities†¦show more content†¦This research demonstrates the importance of understanding the shared meanings of a conversation with both party’s having knowledge of the context and culture. This highlights the nurture influence with these rules being taught and learnt and conflicts with Chompsky view that this knowledge was innate. Much research has been done on the influences of nature and nurture within the topic of sex and gender. ‘There is a world of difference between male/female and masculine and feminine: whereas the former are supposedly biologically prescribed, the latter are psychological characteristics shaped by the experience of growing up’ (Hollway et al. 2002, p119) This explanation goes some way to describing the perception of sex and gender. The biological approach emphasizes the physiological processes and, in most cases, it is the hormones and genes that determine the sex, and to some extent the behaviour patterns. These behaviour patterns were the subject of a study by Money Erhardt in 1972 who research the behaviours of 25 girls who had been exposed to male type hormones in the womb. It was suggested that the girls exhibited a tomboyish behaviour and played more boyishly as a consequence of these hormones. The evolutionary arguments for sex differences focus on the different r eproductive strategies between males and females. This approach concentrates on the optimal reproductive style which is the behaviourShow MoreRelatedSociological and Psychological Theories of Crime Causation1978 Words   |  8 PagesSociological and Psychological Theories of Crime Causation The aim of this essay is to compare, contrast and evaluate two sociological theories of crime causation and two psychological theories of crime causation. Sociological Theories of crime, Labelling and Structural Functionalism/ Strain. Howard Becker is a sociologist that is often credited with the development of the labelling theory. 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