Paraphrasing lab report Essay Example | Topics and Well Written Essays - 1000 words

Paraphrasing lab report - Essay Example These values would allow clear differentiation as they are both known and largely differ with methyl salicylate melting at approximately -8 Â °C and pure salicylic acid at 159 Â °C. The melting point of the product was found to be approximately 160Â °C. Other parameters that were also assessed include the Rf of the substance which was found to be (0.35), as compared to the known Rf and co spot of methyl salicylate (0.75) and pure salicylic acid which is (0.33). In addition, the percent yield was determined to be 93,7%. In summation, the product was confirmed to be salicylic acid and not methyl salicylate due to the values obtained from the TLC tests and melting point. 2. The experimental data illustrated that the purified product has a melting point range of 157-161 Â °C; in addition, pure salicylic acid has a known melting point of 159 Â °C; as opposed to that of methyl salicylate which is -8 to -7 Â °C. The experimental data further illustrated that the melting point of the s ubstance was within the range of 159 Â °C Therefore, the known melting point of salicylic acid is 159 Â °C and it is in close range with that obtained in the experiment of 157-161 Â °C hence concluding that the purified product derived in the experiment was salicylic acid. ... In addition, the product obtained in the experiment is in a similar location to that salicylic acid in the xo spot. Therefore, the values obtained in the TLC and melting point experiments were substantial in concluding the product was salicylic acid not methyl salicylate. The data obtained in the experiments also illustrated that the experiment design was appropriate and the procedure was ideal as the results showed that the production of salicylic acid was successful due to the correlation between the experimental values of the product and the known melting points and Rf co spot values for salicylic acid. This also showed the purity level of the product as it was within the range of pure salicylic acid; hence showing the majority of the impurities had been alleviated from the final product in the recrystallization process. The percentage yield data gives an indication of the reaction and the amount of the product that is practically possible to obtain and isolate. The experiment had a good percentage yield of approximately 93,7% indicating that 6,3% of the product was lost during recrystallization and removal of impurities and vacuum faltering. Table 2. Rf values Compound Distance of Compound movement (cm) Distance of mobile phase movement (cm) Rf Pure salicylic acid 1.7 5.1 0.33 Product 1.8 5.1 0.35 Co-spot 1.7 5.1 0.33 Methyl salicylate 3.8 5.1 0.75 Figure 4. TLC plate 3. In the stationery phase the polarity of the compound determines the Rf value. Hence, salicylic acid will have the lowest Rf value as it has the highest polarity compared to silica gel which is also very polar, resulting in both compounds sticking together. However, non polar compounds such as

Animal testing Essay Example | Topics and Well Written Essays - 1750 words

Animal testing - Essay Example The same government that recommended safety medical test using animals has now provided a contradictory law against animal use in the scientific experiments. Animal rights activists and ecologists have ganged up to protect the welfare of animals by all means. After experiencing the suffering of a frog during a dissection practice lesson in high school, the urge to re-evaluate the consequences of animal testing was unavoidable. The hypothesis of this paper is that animal testing is an unethical practice that should be replaced with alternative medical research procedures. Activists such as Abbot have commended the efforts of the European Centre for Validation of Alternative Methods that will liberate animals from their current burden. By taking a multi-point view, this essay aims at evaluating the pros and cons of animal testing from a neutral ground to expose in black and white the nature of this procedure. Consequently, the readers of this paper will experience an unbiased conclusio n based on the real matters in the animal research practice. Animal Testing in Medical Research My concern for animal testing started right from my high school experience when the anatomy class was required, as part of the curriculum, to dissect a frog and analyze it. I could not figure out the reason for the excitement that the anatomy students displayed throughout the whole experience. I was keen to observe the discomfort of the frog during the dissection process and I realized that animals too, just like human beings, are sensitive to pain. When the entire process was complete, it was the happiness of every student to finally relieve the frog from this torture. Later, I came to learn that the procedure of dissecting a frog was conducted for every anatomy class, not only in my high school, but in most other institutions in the world. In addition, I learnt that animals have been used for a long time not only for dissection but also as test subjects for almost every medicine that hu man beings consume today. This experience of frog dissection in high school has a direct connection with the widespread practice of animal testing that has all along seen animals under experimentation. Although animal experimentation has its own benefits in the medical sector, it is a great source of animal suffering, which should also be a concern for any civilized nation. The complexity of this situation can only be resolved if various dimensions of this issue are carefully evaluated. Animal experimentation is a scientific procedure that has grown slowly but consistently since the evolution of scientific research. The underlying fact is that physiologists in the 17th century saw animal research as a new platform to advance the biological and medical knowledge. This scientific procedure emerged when the scientists identified unique similarity between the toxicology effects of drugs in both humans and animals. Rowan, a writer of the scientist magazine, points out that although the d egree of the effects varied in the two species, scientists found that these differences were minimal and could not hinder the adoption of this procedure. Their concern was to find a testing method that would provide empirical and statistical evidence without subjecting human beings to any harm. The argument was that the human species have the highest priority when it comes to medical research. In these

Digital Literacies and Teenagers Essay Example | Topics and Well Written Essays - 1500 words

Digital Literacies and Teenagers - Essay Example Internet plays a major role in the lives of adults and teenagers alike and the significance of the internet in a teenager's life increases with every day. Teenagers use internet in numerous ways. Internet and digital devices serve as a main source of entertainment to the teenagers. The need for internet becomes vital as long as there is a need for getting faster and in-depth information. The progressively growing internet and computers has become mandatory for teenagers in day to day life. Educators need to keep this in mind and give them a â€Å"head-start† (Thelen par.6) in school. Digital devices are a rage among young people today. Tablets, laptops and smart phones top the teen’s wish lists. MP3 players and other digital gadgets like play stations, palm tops are also widely used by many of today’s students. Digital literacy is a must for the present day teenagers. It is the wave of the future. Today's teenagers will be tomorrow's leaders and working members o f the society. Teenagers who do not have digital literacy will find themselves far behind in the future. Activities of Teenagers on the Internet A new â€Å"Pew Internet Project† survey reveals â€Å"that 93% of teenagers 12?17 go online† (Teen and Young Adult Internet Use. par.1). The frequent activity on the internet by teenagers is the use of social networking sites like Facebook and Twitter. Estimates suggest that â€Å"73%† of teens have â€Å"profiles on social networking sites† (How are Online Issues Affecting Children? Par.7). Social networking sites are forums where information can be posted, shared and uploaded. Teens use these sites to chat with their friends all over the world. Similarly, every teenager with access to computers has an e-mail account. E-mails make communication easier. Commercial sites are used to buy things online, such as books, clothing, or music. To have a video chat conversation with other people chatting tools like Skype and Google Talk etc are used by teenagers. Internet is also used by teens to gather information about â€Å"health, dieting, physical fitness information† (Trends Data (Teens) Par.1) for homework and assignments. Teenagers use internet also to publish journals, articles and research papers. Movies, games and songs are downloaded easily using the internet. Teens also use internet to play online games and watch movies online, using YouTube. Cell phone is the other major characteristic of the present day. It is estimated that â€Å"75% of teens have cell phones† (How are Online Issues Affecting Children? Par.7). Smart phones, which have GPS tracking enable the parents to know the whereabouts of their teens. â€Å"58% of teenagers send â€Å"Instant Messages (IM) or text messages using the site† (Facts and statistics on Teens and Technology par. 3). The student’s curiosity to gather and know more information is quenched by popular search engines like Google, AskJeevs etc. Digital readers and other devices reduce the need for carrying heavy books and notebooks to schools and colleges. Data stored on a computer as reports and assignments can easily be manipulated into a number of different formats, making it easier to study. Communicating and downloading content are two primary uses of the

Animal testing Essay Example | Topics and Well Written Essays - 1750 words

Animal testing - Essay Example The same government that recommended safety medical test using animals has now provided a contradictory law against animal use in the scientific experiments. Animal rights activists and ecologists have ganged up to protect the welfare of animals by all means. After experiencing the suffering of a frog during a dissection practice lesson in high school, the urge to re-evaluate the consequences of animal testing was unavoidable. The hypothesis of this paper is that animal testing is an unethical practice that should be replaced with alternative medical research procedures. Activists such as Abbot have commended the efforts of the European Centre for Validation of Alternative Methods that will liberate animals from their current burden. By taking a multi-point view, this essay aims at evaluating the pros and cons of animal testing from a neutral ground to expose in black and white the nature of this procedure. Consequently, the readers of this paper will experience an unbiased conclusio n based on the real matters in the animal research practice. Animal Testing in Medical Research My concern for animal testing started right from my high school experience when the anatomy class was required, as part of the curriculum, to dissect a frog and analyze it. I could not figure out the reason for the excitement that the anatomy students displayed throughout the whole experience. I was keen to observe the discomfort of the frog during the dissection process and I realized that animals too, just like human beings, are sensitive to pain. When the entire process was complete, it was the happiness of every student to finally relieve the frog from this torture. Later, I came to learn that the procedure of dissecting a frog was conducted for every anatomy class, not only in my high school, but in most other institutions in the world. In addition, I learnt that animals have been used for a long time not only for dissection but also as test subjects for almost every medicine that hu man beings consume today. This experience of frog dissection in high school has a direct connection with the widespread practice of animal testing that has all along seen animals under experimentation. Although animal experimentation has its own benefits in the medical sector, it is a great source of animal suffering, which should also be a concern for any civilized nation. The complexity of this situation can only be resolved if various dimensions of this issue are carefully evaluated. Animal experimentation is a scientific procedure that has grown slowly but consistently since the evolution of scientific research. The underlying fact is that physiologists in the 17th century saw animal research as a new platform to advance the biological and medical knowledge. This scientific procedure emerged when the scientists identified unique similarity between the toxicology effects of drugs in both humans and animals. Rowan, a writer of the scientist magazine, points out that although the d egree of the effects varied in the two species, scientists found that these differences were minimal and could not hinder the adoption of this procedure. Their concern was to find a testing method that would provide empirical and statistical evidence without subjecting human beings to any harm. The argument was that the human species have the highest priority when it comes to medical research. In these

Disneyland Paris & Legoland Essay Example | Topics and Well Written Essays - 4000 words

Disneyland Paris & Legoland - Essay Example Visitor attractions can easily be considered as one of the main economical and social matters in the world today, and this is speaking of theme parks especially particularly; Disneyland Paris and Legoland are two of the most recognized and well known theme parks in the world, and so in order to be able to understand the purpose and reasoning behind theme parks in general, as well as how these two in particular work and what they are all about, there are several questions in particular that need to be answered fully and thoroughly: 1.What is the historical development of Disneyland Paris and Legoland? 2What is the range of current position in the field for Disneyland Paris and Legoland? 3.How does the management and ownership and levels of provision work in Disneyland Paris and Legoland? 4.What is the market for theme parks in general and what is its potential for expansion as a market? 5.What are the key operational management issues? 6.What are some present and future trends and oth er key related issues that are involved here? By thoroughly and rather elaborately answering these questions, we will not only be able to come to a much more knowledgeable and understanding viewpoint on the subject matter at hand altogether, but as well, we will be able to understand theme parks as a whole in general, and furthermore, we will be able to see how they actually work, what type of market they refer to, what the issues are if any, and what trends are in relation to them

David M’Naughten Essay Example for Free

David M’Naughten Essay David M’Naughten hails from Scotland. He earn his living by being a wood cutter. He hardly can make both ends meet and develop hatred to the Prime Minister of Great Britain in the year 1843. To M’Naughten, the Prime Minister was the cause of his personal and financial sufferings due to the failure of the former to run the British government well. In an attempt to get even with the Prime Minister, M’Naughten attempted to kill the leader. M’Naughten was not successful because his ploy was thwarted by the secretary of the Prime Minister and instead killed the secretary and afterwards attempted to murder the Prime Minister. During the trial, nine witnesses testified that M’Naughten was an insane and the jury acquitted him, finding him â€Å" not guilty by reason of insanity † ( pbs. org. n. d. The Right/Wrong M’Naughten Test†. Paragraph 1) Reporter Bill Mears of CNN Washington in 2006 reported â€Å"There was little doubt that Eric Clark, then 17, shot and killed a police officer six years ago in Flagstaff, Arizona. And prosecutors and defense attorneys agreed that the killer had some degree of mental illness he was a diagnosed paranoid schizophrenic who believed he was being constantly watched by aliens from outer space†. â€Å"Teen shot and killed police officer he thought was an alien†, 1st paragraph). Eric Clark believe that the police who accosted him was an alien from outer space who came here to get him, and so, Eric shot and killed him. Eric was found guilty of first degree murder three years after the fatal shooting. Eric defense lawyers entered a plea of not guilty due to insanity. It took three years of deliberation by Arizona court whether Erick will be jailed or sent to mental rehabilitation center while serving the sentence. The court Arizona court ruled Eric to languish in jail for life. Based from the two court decisions just mentioned, it appears that there is sort of disagreement among the different U. S. legal courts as to the legal definition of insanity and its acceptance as legal defense in court. This essay will trace the development of insanity as legal defense from its origin up to what it is in today’s legal battle. Evolution of insanity defense As early as 1581, insanity defense has been well considered in Anglo-American law and a legal treatise was enacted saying that â€Å"If a madman or a natural fool, or a lunatic in the time of his unacy do [kill a man], this is no felonious act for they cannot be said to have any understanding will â€Å" ( pbs. org. n. d. â€Å"A Brief History of Insanity Defense†, paragraph 3 ). There was no available record of court proceeding from the date of treatise enactment up to 17th century. Three hundred years later, the British court elaborated the treatise and gave rise to the â€Å"wild beast test† ( 4th paragraph ) which emphasized that â€Å"If a defendant was so bereft of sanity that he understood the ramifications of his behavior no more than in an infant, a brute, or a wild beast, he would not be eld responsible for his crimes ( 4th paragraph). In other words, if the defendant lacks sanity and cannot comprehend the outcome of what he did, as his ( defendant) mind is that of infant or a wild animal, then the defendant is not liable for the crime committed. The codification of this British â€Å" wild beast test† was put at stake in 1843, in the case of David M’Naughten as outlined in our introduction. Queen Victoria was not impressed with the decision of the court and requested a review of the case with a panel of judges. The resulting decision was â€Å"that a defendant should not be eld responsible for his actions if he could not tell that his actions were wrong at the time he committed them â€Å" (The Right/Wrong M’Naughten Test†. Paragraph 3). This was also mentioned in the research of Chiacchia ( 2001) and law. jrank org. n. d. ) This became the basis of the insanity defense in England and adopted by American courts and legislatures for more than 100 years without any modification. Up to 1998, 25 states including the District of Columbia adopted this Right/Wrong M’Naughten Test†. According to legal critics, the M’Naughten test has one major rawback. While the rule focus on the ability to distinguish right from wrong (which is cognitive in nature), it failed to consider the unstoppable desire that was the dominant feeling before and during the consummation of the crime. This resulted to modification of the M’Naughten rule by adding a provision called irresistible impulse ( â€Å"Irresistible impulse†, 1st paragraph). The added provision in effect will absolve a defendant who can distinguish between right and wrong but unable to stop the crime due to his uncontrollable desire to consummate it to get even with the victim. A number of tates adopted the M’Naughten modification and coined another name as â€Å" policemen in the elbow test† (1st paragraph). The name clearly highlight the intense desire to consummate the crime as even if there is police authority around to witness, the defendant will do it. In 1950, advances in psychiatry and psychology as a science was very noticeable. In the light of the advances, legal critics saw the M’Naughten rule as too rigid and antiquated. In 1954, an appellate court discarded the M’Naughten and â€Å" irresistible impulse â€Å" test in favor of a more scientific and medically based insanity test. This became the basis of the Durnham â€Å" Mental Defect† rule. In Durnham v. United States, The U. S. Court of Appeals of the District of Columbia ruled that a defendant is not guilty † if his unlawful act was the product of mental disease or mental defect. (â€Å" The rise and fall of the Durnham â€Å"Mental Defect† rule, 1st paragraph). The decision was considered as within the demand of the times and a major breakthrough in American legal system as it exemplify the replacement of moral considerations with a more neutral and scientific evidences reflective of the advances of psychiatry and psychology ( â€Å" The rise and fall of the Durnham Mental Defect† rule). Legal experts claim that the Durnham rule is vague and difficult to apply. According to the experts, the term â€Å"mental defect† is very broad and they were concerned that due to its vagueness, more and more defendants will be acquitted than before. The confusion arises over the interpretation of â€Å" mental disease or defect† clause. Will mental defect mean only psychosis or any of the minor mental disorder found in Diagnostic and Statistical Manual of Mental Disorder (DSM). Critics were concerned of the possibility that defendants will use alcoholism and other ental disorder with antisocial behavioral symptoms as defense of their crimes. Also, it is not clear where the burden of proof is; that is whether it’s up for the court to determine the mental defect or the burden lies with the defendant and the psychiatrist as professional witness. Another disagreement is that the Durham test inadvertently grant too much influence to the psychiatrist and psychologist as to the result of the court trial. Twenty two states rejected the Durham test in 1972 and a panel of judges considered the Model Penal Code Test of the American Law Institute ( A. L. I. as eplacement (pbs. org. n. d. ). The A. L. I. standard is intended to soften the M’Naughten with the â€Å"irresistible impulse† by introduction of medical and psychiatric evidence requirement. The A. L. I. standard, rule â€Å"that a defendant will not be held criminally responsible if at the time of the behavior in question as a result of a mental disease or defect, he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law. (pbs. org. n. d.  A Brief History of Insanity Defense, â€Å"The A. L. I. Standard†, 1st paragraph). In ddition to requiring the defendant to show proof that at the time of the consummation of the crime, there is absolutely no understanding as to the nature of the act ( as in M’Naughten test), a certification from a psychiatrist or psychologist is needed to attest to the fact that the defendant lack â€Å" substantial capacity† ( paragraph 2, line 4 ) to understand the right f rom wrong together with the irresistible impulse consideration. Under the A. L. I. tandard, the act of serial killers whose mental defect manifests only during the act of killing and shows normal mental behavior before and after he consummation of the act can lead to his/her conviction. In 1998, 22 states used the A. L. I. rule while 26 used the M’Naughten version regardless of the irresistible impulse clause. It is also provided in the A. L. I. standard, the provision for due process and equal protection concerns for those who were acquitted by reason of insanity for automatic and indefinite confinement to assess and treat their mental disorder and check their dangerousness potential to society periodically. If found during the evaluation that further confinement is no longer needed, then the defendant can be eleased. By early 1980’s all state legislatures except for 10 has reformed their laws incorporating the provision for periodic review. In 1981, a test for stability of the A. L. I. standard ensued. John Hinckley, Jr. , a Washington police officer and secret service agent shot then U. S. President Ronald Reagan and his press secretary James Brady. Hinckley claimed during the trial the following: that he was trying to impress the actress Jodie Foster, with whom he was infatuated. He later described the incident in a letter to The New York Times as the greatest love offering in the history of the world. At one time Miss Foster was a star and I was the insignificant fan. Now everything is changed. I am Napoleon and she is Josephine. I am Romeo and she is Juliet (pbs. org. n. d. A Brief History of Insanity Defense, â€Å"After Hinckley† , 1st paragraph). Hinckley was acquitted by the jury of 13 assault, murder and weapon counts and moreover, ruling him not guilty by reason of insanity. This resulted to a great American public uproar that call for thorough review of the insanity defense strategy and plugging loopholes in the justice system that allows an obviously guilty man to escape punishment. Senator Dan Quayle claimed that the insanity efense allowed pampering of criminals by allowing them to kill without conscience. The psychiatric and legal professional group called for the modification instead of total abolition of the insanity defense resulting to legislation called â€Å" The Insanity Defense Reform Act of 1984† ( 3rd paragraph). The act is a stricter version of the M’Naughten rule. The Cornell University Law School in 2006 released the following information related to a more stricter version ( article 17, Insanity defense, U. S. Code Collection, 1st paragraph) (a) Affirmative Defense. — It is an affirmative defense to a prosecution under any Federal statute that, at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts. Mental disease or defect does not otherwise constitute a defense. (b) Burden of Proof. — The defendant has the burden of proving the defense of insanity by clear and convincing evidence The burden of proof now is with the defendant and not with the prosecution. The defendant in order to qualify for the insanity defense must show proof that the disorder is severe. The volitional test that excused a defendant who lacked the capacity to fight the â€Å" irresistible impulse† was eliminated, in effect going back to the M’Naughten â€Å" right/wrong â€Å" standard of the 19th century. The influence of psychiatric testimony was effectively limited and more stricter procedure on hospitalization and release of those acquitted was put into effect. Thirty states adopted â€Å"The Insanity Defense Reform Act of 1984 † while the three states of Montana, Utah and Idaho abolished completely the insanity defense strategy. In the year 2000, a provision to â€Å"The Insanity Defense Reform Act of 1984 † was enacted nd 20 states instituted it. The provision is called â€Å" Guilty But Mentally Ill â€Å" or GBRI ( Chiacchia. 2006. Insanity defense, â€Å" Guilty but mentally ill†, 1st paragraph, line 2. ). Under the GBRI, the defendant can be sentenced guilty although he is legally insane. The convicted will be jailed and his mental illness will be checked by the government periodically. The criticism of GBRI lies on the fact that very few jail institution can actually look at the mental state of the convicted insane. Examining the success of using the insanity defense in this modern time, Chiacchia ( 2001 ) eported ( â€Å" Insanity defense statistics, 2nd paragraph) that: Successful NGRI defenses are rare. While rates vary from state to state, on average less than one defendant in 100-0. 85 percent-actually raises the insanity defense nationwide. Interestingly, states with higher rates of NGRI defenses tend to have lower success rates for NGRI defenses; the percentage of all defendants found NGRI is fairly constant, at around 0. 26 percent It shows from the statistics that the chances of acquittal using the insanity defense is very slim, considering that practically every loop hole in the American jurisprudence has been effectively ealed with the adoption of â€Å"Guilty But Mentally Ill† provision. Summary and Conclusion It is now a known fact that the insanity defense dates back in 17th century in Great Britain with the acquittal of David M’Naughten. The M’Naughten Right/Wrong Test underwent five modifications from 17th century up to the present time. A number of celebrated cases involving rich families and big political figures as victims in the past three centuries resulted to acquittal of the defendants in the light of the different legal interpretation of insanity defense among states. The acquittal of John Hinckley, Jr. who shot then U.  S. President Reagan and killed his press secretary in 1981 was the strong force that caused widespread public clamor for reviewing and unification of interpretation of the insanity defense strategy. At present, all states except for three ( Montana, Utah and Idaho which scrapped the insanity defense in its entirety) enacted the M’Naughten rule with modifications centered on the burden of insanity proof on the defendant. Twenty states enacted â€Å"The Insanity Defense Reform Act of 1984 † with provision for Guilty But Mentally Ill, shutting the loopholes.

Determination of coefficient of expansion of air

Determination of coefficient of expansion of air INTRODUCTION This experiment is based on investigating the coefficient of expansion of air using a simple laboratory set up; the stopper flask method, where pressure is constant throughout the experiment. The increase in volume of a gas is directly proportional its temperature increase and is expressed as a fractional changed in dimensions per unit temperature change. Air will easily expand when it is heated and contract when it is cooled. The aim of the experiment was to: * Determine the coefficient of expansion of air using a stoppered flask method. The flask was stoppered and a thick tube allowed interactions with the outside. The flask was heated in a beaker (with water) and then transferred immediately to cold water where the cold water was allowed to enter and air within the flask decreased. The initial and final volumes of air and water was calculated (directly or indirectly whichever appropriate) and the coefficient was calculated from these. The experiment in its design allowed the calculation of the coefficient of expansion of air to be 3.22 * 10-3 K-1. This was calculated at a temperature of 24oC and pressure of 1 atm, which gives a good approximation compared to the theoretical value of 3.37 * 10-3 at a temperature of 24 oC (297 K). THEORY Dooley (1919) indicates that gases are said to be perfectly elastic because they have no elastic limit and expand and contract alike under the action of heat. That is to say, every substance when in the gaseous state and not near its point of liquefaction has the same coefficient of expansion, this coefficient being 1/273 of its volume for each degree Centigrade. He further goes on to say that since a gas contracts 1/273 part of its volume when its temperature is lowered 1 ° C, such a rate of contraction would theoretically reduce its volume to zero at a temperature of 273 ° C. Since all gases reach their liquefying point before this low temperature is attained, however, no such contraction exists. At the same time, it may be said that if heat is considered as a motion of the molecules of a substance, that motion is to be considered as having ceased when the temperature has reached 273 ° C. This is the expansion coefficient of an ideal gas. GAY LUSSACS LAW Madan (2008: 81) indicates that the coefficient of expansion of a substance at any given temperature, t, is the small fraction of its volume by which one cubic centimeter of the substance will increase when heated from to. * Gases are affected by changes of temperature in the same general way as liquids and solids, expanding when heated and contracting when cooled. * For a given change in temperature, they change in volume to a far greater extent than either liquids or solids. * All gases, at temperatures considerably above their liquefying points, have practically the same coefficient of expansion. This was first observed by Gay Lussac and Charles, and is a very remarkable one, and a great contrast to what has been noticed in the case of solids and liquids, each of which has its own special coefficient of expansion, often differing widely from those of others. EXPANSION AGAINST CONSTANT PRESSURE Atkins (2006: p35) indicates that: By definition: At constant pressure: This indicates that the work done is actually the difference between the final and initial volumes multiplied a unit of pressure (which is constant). Once can say therefore that a gas expands (independent of pressure) but dependant on temperature as given by: METHOD Method as per hand out, however, a small beaker with water was used to heat the flask and atmospheric pressure was used instead of reading the barometric height (which was not available). MATERIALS/APPARATUS  · Conical Flask (100 mL)  · Rubber Stopper  · Metal Clip  · Short Glass Tube  · Heater  · Beakers (500 mL) 2  · Thick Walled Rubber Tube  · Thermometer (0 100oC)  · Electric Balance Weight of flask + fittings 136.4 + 0.1 g Weight of flask + fitting + water sucked in 168.6 + 0.1 g Weight of water sucked in 032.2 + 0.1 g Weight of flask + fittings + full water 279.8 + 0.1 g Weight of full water 143.4 + 0.1 g Temperature of boiling water 103.0 + 0.1 oC Temperature of cold water 024.0 + 0.1 oC Atmospheric Pressure 1.00 atm Volume of gas @ 103.0 oC 143.4 + 0.1 cm3 Volume of gas @ 24.0 oC 111.2 + 0.1 cm3 DISCUSSION The experiment investigated the coefficient of expansion of air. This value was found to be 3.22 * 10-3 experimentally. One would infer, at first glance, that the volume of air initially would have been the volume of the flask (100 mL), as the volume of a gas is the actual volume of the container. But why was the mass of the beaker found (filled with cold water)? Was it to give a better estimation of the volume of the air? By finding the volume using the density of water, it was found to be 143.2 cm3 which is a large difference compared to the 100 mL of the flask. Then one realized that the flask was filled to the top close to the stopper itself, and therefore assuming that the volume of air was 100mL would have been a grave mistake and calculating the volume by density was the best and accurate method to use. The experiment relies on the fact that the volume of a substance, in this case, air, is dependent on the temperature of the system. The flask (opened) was heated in boiling water, this was indirect heating of the flask, it allowed the inside of the flask to be dry and consequently allowed the air to be dry. In addition, by heating the flask in boiling water, the temperature of the air inside the flask increased as well (according to the zeroth law of thermodynamics), indicating that there will be some form of thermal equilibrium. At this point, the initial volume and temperature of the air will be obtained. The tube was closed with a clip and placed in the water at a lower temperature. The question that arises at this point is why was the clip closed? A logical assumption is that to disallow further interaction between the atmospheric air (at a lower temperature) and the flasks air (at a higher temperature), also one can say that because of the temperature gradient, their will want to escape and in so doing create a thermal equilibrium between the two. The water was allowed to enter, to replace the air and thus the volume of air decreased. This method was unique in its design that it used a backward approach. Rather than obtaining the expansion of air from a lower to a higher temperature, it measured the contraction of the air from a higher to a lower temperature. In the end, the initial and final volumes and temperatures of the air being considered were obtained, and thus the coefficient was able to be calculated. SIGNIFICANCE OF EXPANSION COEFFICIENT The value ascertained experimentally was 3.22 * 10-3. This can be termed a fractional change as it is very small (0.001th of a value 3.22). It can be inferred that this fractional change affects the volume of the sample when a rise in temperature occurs. It means therefore, that for every change in temperature from to to (t+1)o, the volume of air in one cm3 of air will increase by 3.22 * 10-3 at 1 atm (experimental condition). A small value of ÃŽÂ ±, indicated by Atkins (2006) implies that it responds weakly to changes in temperature i.e. the air responds weakly to changes in temperature which is important in life itself, as air responding strongly to temperature changes would be hazardous to our health, and may even result in cardiac arrests with sudden decreases in temperature (during winter time in north America and Europe among other places) and where there are heat surges. COMPARING EXPERIMENTAL AND THEORETICAL EXPANSION COEFFICIENT The theoretical value of the expansion coefficient should be, since. The deviation is (3.37 * 10-3- 3.22 * 10-3) = 1.5 * 10-2. This deviation represented almost 4.66% of the theoretical value! What can account for this deviation? It all leads to experimental errors, since pressure is constant. Obviously, by looking at the formula, the process of obtaining the final and initial volumes and temperatures will have an effect on the expansion coefficient. The volume of water sucked in may not have been at maximum due to hindrances in the tubing attached to the flask, or the water was not allowed to go in as fast as it should. Also, one can consider that the density of water used to calculate the volume of air after the water had been sucked in may have been different and hence affected the calculated the volume). All of these can contribute uncertainties to the coefficient of expansion and can be used to explain the difference observed. SOURCES OF ERRORS * The difference between the experimental and established values is therefore attributed to factors such as temperature, volume, and the accuracy at which these values were obtained as described above. * The density of water probably affected the results when it was used to calculate the final volume of air and initial volumes of air. * Within the limits of experimental error, the value ascertained was close to the theoretical value with only about 5% deviation. * The volumes and temperatures had uncertainties of + n, where n represented the volume and temperature. The final result of the coefficient had an uncertainty of 0.41%. LIMITATIONS * The method did not allow the calculations of the volumes and temperatures directly but indirectly. A direct method, if possible, would have contributed to a more accurate value of the coefficient of expansion. * The experiments were not repeated to ascertain different values of the volumes and temperatures. Averaging the values would have allowed a more accurate value of the temperatures and volumes and by extension the coefficient of expansion. ASSUMPTIONS * It was assumed that air was ideal in nature and followed the ideal gas equation. Introduction of van der waals coefficient would have proved to be more tedious in calculating the coefficient of expansion of air. * It was assumed that the volume of dry air in the flask was the volume of the water in cm3. As mentioned previously, the water was filled to the top of the flask (close to the stopper), and assuming 100mL would have been grossly inadequate contributing to more uncertainties and thus a more inaccurate value of the expansion coefficient. * It was assumed that rate at which the temperature and volume decreased when the flask was placed in the water allowed the expansion coefficient to be ascertained. This was very important, as it implied that the temperature affected the expansion and or contraction of air and water which ultimately enabled the calculation of the coefficient. CONCLUSION With reference to the aim, it can be concluded that the experiment in its design allowed the calculation of the coefficient of expansion of air to be 3.22 * 10-3 K-1. This was calculated at a temperature of 24oC and pressure of 1 atm. BIBLIOGRAPHY Anand, A and Negi, S. A Textbook of Physical Chemistry. USA: John Wiley Sons, 1985. Atkins, Peter and De Paula, Julio. 2006. Physical Chemistry 8th Edition. USA : W. H Freeman Company, 2006. Castellan and Gilbert. 1983. Physical Chemistry 3rd Edition. Massachusetts: Addison Wesley Publishing Company, 1983. Chirlian and L.E. Chemistry 103 Home Page. Department of Chemistry 103. [Online] [Cited: November 7, 2009.] http://www.brynmawr.edu/Acads/Chem/Chem103lc/chem103.html. Daley, Henry and OMalley, Robert. 1988. Problems in Chemistry 2nd Edition. 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