Determining Avogadro’s Constant and Faraday’s Constant

Determining Avogadro’s Constant and Faraday’s Constant List of Apparatus Name of Apparatus Quantity Uncertainty Electronic Stopwatch 1  ±0.2s Ammeter 1  ±0.01A Wires with crocodile clips 1 D.C power source 1  ±0.01V 300cm3 Beaker 3 Copper strips 2 Sand paper 1 Graphite rod 2 pH probe/data-logger 1  ±0.2 Electronic weighing balance 1  ±0.001 DATA COLLECTION: The electrolytic cell used in this investigation is illustrated in Fig 1: Fig 1 Diagram of electrolytic cell used in investigation In this investigation, a current is passed through the solution with copper as the cathode and graphite as the anode. After a set amount of time, the circuit is disconnected and the mass of the cathode is measured. Following which, calculations are made so as to determine the Avogadro’s and Faraday’s constant. Qualitative Observations When the D.C power source was turned on, bubbles were formed at the Graphite anode. As the reaction progresses, powdery substance gets suspended in the solution and a black solid deposits can be found at the bottom of the beaker and there is a visible decomposition of the graphite electrode. As the reaction progress, a pink layer of copper forms on the copper strip. The copper strip is originally brown in colour while the graphite electrode is black in colour. Eventually, as the graphite electrode decomposes, the graphite molecules will turn the copper (II) sulphate solution from blue to black in colour. However, when the copper sulfate solution is filtered, it is noted that there is a decrease in the intensity of the blue colour in the filtrate after the electrolysis. The initial pH of the solution is 2.75, after the electrolysis is carried out, the pH decreases to 2.10. Data Collection Constant variables Time Interval/s( ±0.2) 300 Voltage/V 4V Current/A( ±0.01) 0.25 Cathode Trial 1 Initial mass/g ( ± 0.001 g) 1.315 Final mass/g ( ± 0.001 g) 1.279 Change in mass/g ( ± 0.002 g) 0.036 Chemical equation for reaction at the anode: 2H2O (l) à ¯Ã†â€™Ã‚  O2 (g) + 4H+ + 4e (aq) Chemical equation for reaction at the cathode: Cu2+ (aq) + 2e à ¯Ã†â€™Ã‚   Cu (s) Calculations for cathode Calculations Error Propagation Change in mass(Cu) = 0.036g Mols of (Cu) = =5.7 x 10-4 mol Number of mol of electrons- Using mol ratio Cu2+ (aq) + 2e à ¯Ã†â€™Ã‚   Cu (s) Number of mol of electrons =11.4 x 10-4 Charge flowing through circuit Number of electron charges in circut= Where is the elementary charge, the charge of one electron Number of electron charges in circuit = Number of mol of electrons Where L is the Avagandro’s constant Equating the number of mols of electrons obtained form the copper mass data and the number of mol of electrons from the current- Faraday’s constant = = 67000 C % ±ÃŽâ€ Mol of Cu = % ±ÃŽâ€ Mol of Cu = = 5.6 % % Uncertainty of number of mol of electrons = % uncertainty of Mass(Cu) =5.6% % uncertainty of number of mol of electrons =5.6% % ±ÃŽâ€ charge flowing in circuit = Percentage error Percentage error for Faraday’s Constant = = = 30% Percentage uncertainty of faraday’s constant =5.9% Percentage systematic error in Faradays’ constant =%error-%random error = 24.1% Percentage error for Avogadro’s Constant = = 30% Percentage uncertainty of Avogadro’s Constant =5.9% Percentage systematic error in Avogadro’s Constant =%error-%random error = 24.1% Conclusion In conclusion, the calculated value of Faraday’s constant is mol-1 and Avogadro’s constant is. As seen above, the percentage error for both Faraday’s constant and Avogadro’s constant are both 30% and after subtracting the error due to instrumental uncertainty, the % systematic error obtained is 24.1%. This shows that the experimental values calculated differ greatly from the literature values, indicating that there has been a significant amount of systematic error, which has caused the calculated value to be much different from the literature value. As percentage error of both Faraday’s constant and Avogadro’s constant are much larger than their respective percentage uncertainties, this indicates that the sources of systematic error are significant and cannot be ignored Evaluation Type of error Limitation Improvement Systematic Oxidation of copper occurs naturally when the copper strip is exposed to oxygen and when it is heated in the oven. Even when sand paper is used to scratch off the layer of copper oxide on the surface of the, it is difficult to completely rid of all the copper oxide. The formation of copper oxide will affect the reaction when electrolysis occurs and will affect the change in mass of the copper electrode, which is the dependent variable in this experiment. Even when the copper strip is immersed in the copper (II) sulphate solution, after a period of time, it will eventually start to form a layer of copper (II) oxide which will not be involved in the electrolysis reaction. This will reduce the amount of copper which will undergo reaction, causing it to reduce the eventual calculated Faraday’s and Avogadro’s constant. It is impossible to prevent the oxidation of copper from happening however, this systematic error can be minimised. Other than ensuring that the layer of copper oxide is scratched off by rubbing the copper strip excessively with sandpaper. The time for which the copper stays in the oven can be minimised or hair dryer can be used instead to blow the water off. Systematic When the graphite electrode starts to disintegrates as the reaction progresses, fragments of graphite will be dispersed throughout the entire solution. As copper (II) ions move towards the copper strip to plate it, some of the graphite fragments may end up attached to the copper strip as well and are unable to fall off as a layer of copper plates over the graphite fragments. This can be observed in the experiment when the copper strip is removed at the end of the experiment; black fragments of graphite are observed on the copper strip. The graphite fragments would easily reach the copper strip mainly because they were quite near each other. Hence, the graphite fragments could easily move towards the copper strips and attach to them. In order to minimise this from happening, the experiment should be conducting in a 500cm3 beaker, with the copper strip and the graphite electrode held further away from each other. Also, the graphite electrode should be positioned below the copper strip so that as the graphite electrode disintegrates, the graphite fragments will simply sink towards the bottom of the beaker, hence it will be less likely for the graphite fragments to accidentally coat onto the copper electrode Systematic Fluctuations in the current. Whenever the 2 electrodes were moved, the current of the circuit changes. Hence, whenever the copper electrode was moved in order to be weighed, the current would fluctuate, resulting in an inconsistent current throughout the experiment. If the current deviates from the stated 0.25, the resulting Faraday’s constant and Avogadro’s constant will be affected as well. An increase in current will result in an increase in the Faraday’s constant and Avogadro’s constant calculated while a decrease in current will result in a decrease in the Faraday’s constant and Avogadro’s constant calculated. In order to prevent fluctuations in the current as a result of the shifting electrodes, a retort stand can be used to hold the electrodes in place and prevent them from moving. This is much more reliable than just using hands to hold the electrode, resulting in a reduction in the fluctuation of the current A rheostat can be used and included in the circuit in order to adjust the amount of resistance of the circuit so that the desired current can be achieved. As current is inversely proportionate to resistance according to Ohm’s law, the resistance of the circuit can be adjusted in order to ensure a consistent current of 0.3 throughout the experiment. Systematic Also, another source of systematic error in this experiment would come from the fact that, the reading on the ammeter does not indicate the actual electric current flowing through the electrodes and the electrolyte as this value may decrease due to power losses in the wires. That is the electrical energy would be converted to heat. However the resistance of the wires in the circuit was assumed to be negligible in this experiment for simplicity. This would lead to systematic error as we would consistently overestimate the magnitude of the current flowing through the electrolyte. This error can be avoided if the values of the resistance of the wires as well as the internal resistance of the power source were known and included in the calculations made. Systematic The copper electrode may undergo a process called passivation[1] where the metal forms a protective layer on its surface to protect it from outer factors such as water or air to prevent corrosion. Such a protective layer will result in a high resistance which will lead to a voltage delay. This process may also occur on the graphite electrode. During the reaction, in the presence of passivation, the initial rate of the increase in mass of the copper electrode will be slowed down; ultimately affecting the total gain in mass by the copper electrode, affecting the Faraday’s constant and Avogadro’s constant calculated. This process of passivation can be removed by allowing the reaction to progress for 5 minutes to avoid a voltage delay. 5 minutes was chosen because too short a time will be insufficient to remove the protective layer on the electrode and too long a time will result in the disintegration of the graphite electrode even before the collection of data has begun. As mentioned above, if there is too much graphite fragments in the copper (II) sulphate solution, they may come into contact with the copper electrode and affect its final mass as copper ions plate over the graphite fragments on the copper electrode. Random Error Due to time constrains, only one set of data was collected. This will result in the fluctuation of the value of the Faraday’s and Avogadro’s constant. In order to reduce the error, perhaps more sets of data can be collected, so that a graph of metal deposited against time can be plotted and the gradient will enable the determination of the two constants. [1] Metal passivation-en.w,wikepedia.org/Passivation_(Chemistry). Accessed- 26/2/2014)

Interpretation Job

I deem the Graduate Trainee Program as one of the epitomes of Centrelink's thrust in showcasing the best and brightest Australia has to offer the international community. Being part of a vibrant, dedicated and diverse group of individuals entrusted to foster understanding and promote the country's foreign and trade relations is a challenge anyone who believes in Australia should be proud to be a part of. Having read Politics and Government in university and presently doing my post-graduate studies in International Relations give me the fundamental, if not advanced, skills as well as awareness of local and international socio-political and economic realities of today. Complementary to my academic skills are the English language teaching experiences I have locally and abroad, which contributed immensely to my understanding of different cultures and peoples of varying age group. Being trilingual (English, Korean and street Japanese) gives me the edge to appreciate not only the language of other people but the nuances of what a language conveys, this is a paramount trait in comprehending the distinct language of diplomacy. It has helped me deal with clients in an interpretation job, students in a teaching assignment or local tribes people in medical or mercy missions. One of the jobs I do on the side is translation and interpretation work from Korean to English and vice versa. This type of work deals with Korean trade delegations coming to Australia to deal with Australian business owners. Both Korean and Australian clients require submission of a written project proposal prior to getting the tasking. The proposal calls for demonstrating my competence and advanced level of understanding not only of the Korean and English languages but the cultures as well. In writing the proposal, I set my plan of action and the methodology to be used for the translation and interpretation processes. After the clients read through my proposal, I present it to both parties and convince them of my being the right person to get the job done. During the actual translation/interpretation work, I sometimes observe that the principals' understanding of what each said to the other may get â€Å"lost in translation. † The outcome of which is that on several occasions, I had to mediate and arbitrate so that the two factions agree on correct interpretations. It is noteworthy seeing conflicting parties come to terms because of my diplomatic approach and diligence in getting the job done properly. In 2001, while doing community re-building voluntary work with the Youth with a Mission (YMAN), a non-government organization assisting marginalized communities worldwide, I was a â€Å"trainee team leader† charged with a group of young volunteers from the United States, Canada, Australia, Fiji and even Australian aborigines. We were in northern Thailand amongst the Karen and Hmong tribes and I found out that due to their patriarchal society, the males in the tribes refused to work with our female volunteers. This caused some setbacks since individual assignments were already given prior to arriving on site. As the team leader of the group, I discussed this problem with the senior team leader and recommended that we should respect their culture in order to complete the mission. I talked with the team and organised the male volunteers to work in building houses and improving the local site. The female volunteers took on the English teaching assignments and medical assistance. This went well with the local populace and we gained their respect because we demonstrated our reverence for their beliefs. I would have done things differently by studying the culture, beliefs and peculiarities of the tribes first prior to embarking on another volunteer mission. Team success rests with good leadership and management. I related the leader and manager role since despite being distinct characteristics, they are inseparable traits of someone charged with such daunting assignment. A leader/manager must have the vision to effectively implement tasks and the steadfastness to successfully complete mission objectives. My value as a team member is the ability to work cohesively with each team member and agree to set aside idiosyncrasies in order to fulfill collective goals. People with different backgrounds can be incorporated in a team by appealing to their individual aims and marry them with the strategic objectives. During one of my courses in post-graduate studies, our class simulated a United Nations Security Council meeting and I played the part of the Secretary General. We were doing North Korean nuclear proliferation conflict resolution and individuals have their own opinions on how best to mitigate the problem. Playing the goodwill role, I contributed to the team output by consolidating valid points from individuals and getting a group consensus that the solution to North Korea's nuclear arms program is by catering to the North Korean's need for aid in exchange for reduction or total demobilization of the nuclear arms. While working as a contractual English instructor in Korea, I noticed that the students learning English, though very diligent and hardworking, English have a hard time with conversational, street-speak and business English. This is due to the formation of the program wherein they learn classroom and â€Å"theoretical† English but lacking the suave and practical application. Korea is a very rigid and structured society and change usually comes at a difficult phase. I adapted and conformed to the norms of the school but took the initiative by instructing my students to prepare a five-minute oral presentation of a country of their choice. The presentations have to be made with individually hand-made posters to have more impact in terms of graphics. After each student's presentation, critiques from the class – in English, were done and this further confirmed the value of the pioneering teaching methodology. Needless to say, my technique was adapted by other teachers, who found it more efficient than the processes they have been using for years. Even the school director was pleased with my achievement that when my contract ended, he offered to renew it but I declined since I had to go back to Australia to pursue my studies.

Tuberculosis Is An Illness Of The Elderly, The Alcoholic,...

Introduction Pulmonary tuberculosis is an illness of the elderly, the poor, the alcoholic, and, today, the drug addict. TB, an indication of the frightening mortality of tuberculosis is contained in a report written about New York City in 1826. At that time New York had a population of 166,086. The total number of deaths in the two years preceding the report was 9,359, of which 1,579 were due to consumption. This means TB accounted for 17% of deaths due to all causes. Even today, almost 150 years later, TIn 1971 in New York City there were 310 recorded deaths from TB. In 1972 the total rose to 331. Once up on a time although Pulmonary TB a leading cause of death was under control in US, still hundreds of cases were reported every week†¦show more content†¦TB patients need to take two first line drugs for a period of 18 months – two years, with this chemotherapy patient is non infectious within a period of 2 weeks and can come back to his normal daily activities even going back to work also. As a result hospitalization for TB these days is minimal; patients who tested positive for TB were usually hospitalized until smear is negative continuing the chemotherapy on an outpatient basis. Hospitalization is also useful in assessing or analyzing the drug side effects during chemotherapy. Role of nurse 25 years ago taking care of a patient infected with TB for a nurse was very complicated and the nurse would be late in completing her assignments due to time consuming isolating techniques at complete bed rest and facing an anxious patient for months and even years making the job undesirable and there was also a danger the nurse who is treating TB patient would infect herself with TB. But the breakthrough in the chemotherapy in the treatment of TB has distinctly affected the role of nurse. The new TB drugs have eliminated most of the dangerous aspects that involved in TB patient care, but the new role of nurse is more difficult because of increased responsibility, the success of treatment for TB depends on the patients regularly following the medication for a long period just like Hypertension and it is the duty of R.N’s to make certain

Biomedical of Health - 768 Words

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