How To Calculate Avogadros Number Experimentally

Avogadros number isnt a mathematically derived unit. The number of particles in a mole of a material is determined experimentally. This method uses electrochemistry to make the determination. You may wish to review the working of electrochemical cells before attempting this experiment. Purpose The objective is to make an experimental measurement of Avogadros number. Introduction A mole can be defined as the gram formula mass of a substance or the atomic mass of an element in grams. In this experiment, electron flow (amperage or current) and time are measured in order to obtain the number of electrons passing through the electrochemical cell. The number of atoms in a weighed sample is related to electron flow to calculate Avogadros number. In this electrolytic cell, both electrodes are copper and the electrolyte is 0.5 M H2SO4. During electrolysis, the copper electrode (anode) connected to the positive pin of the power supply loses mass as the copper atoms are converted to copper ions. The loss of mass may be visible as pitting of the surface of the metal electrode. Also, the copper ions pass into the water solution and tint it blue. At the other electrode (cathode), hydrogen gas is liberated at the surface through the reduction of hydrogen ions in the aqueous sulfuric acid solution. The reaction is:2 H(aq) 2 electrons - H2(g)This experiment is based on the mass loss of the copper anode, but it is also possible to collect the hydrogen gas that is evolved and use it to calculate Avogadros number. Materials A direct current source (battery or power supply)Insulated wires and possibly alligator clips to connect the cells2 Electrodes (e.g., strips of copper, nickel, zinc, or iron)250-ml beaker of 0.5 M H2SO4 (sulfuric acid)WaterAlcohol (e.g., methanol or isopropyl alcohol)A small beaker of 6 M HNO3 (nitric acid)Ammeter or multimeterStopwatchAn analytical balance capable of measuring to nearest 0.0001 gram Procedure Obtain two copper electrodes. Clean the electrode to be used as the anode by immersing it in 6 M HNO3 in a fume hood for 2-3 seconds. Remove the electrode promptly or the acid will destroy it. Do not touch the electrode with your fingers. Rinse the electrode with clean tap water. Next, dip the electrode into a beaker of alcohol. Place the electrode onto a paper towel. When the electrode is dry, weigh it on an analytical balance to the nearest 0.0001 gram. The apparatus looks superficially like this diagram of an electrolytic cell except that you are using two beakers connected by an ammeter rather than having the electrodes together in a solution. Take beaker with 0.5 M H2SO4 (corrosive!) and place an electrode in each beaker. Before making any connections be sure the power supply is off and unplugged (or connect the battery last). The power supply is connected to the ammeter in series with the electrodes. The positive pole of the power supply is connected to the anode. The negative pin of the ammeter is connected to the anode (or place the pin in the solution if you are concerned about the change in mass from an alligator clip scratching the copper). The cathode is connected to the positive pin of the ammeter. Finally, the cathode of the electrolytic cell is connected to the negative post of the battery or power supply. Remember, the mass of the anode will begin to change as soon as you turn the power on, so have your stopwatch ready ! You need accurate current and time measurements. The amperage should be recorded at one minute (60 sec) intervals. Be aware that the amperage may vary over the course of the experiment due to changes in the electrolyte solution, temperature, and position of the electrodes. The amperage used in the calculation should be an average of all readings. Allow the current to flow for a minimum of 1020 seconds (17.00 minutes). Measure the time to the nearest second or fraction of a second. After 1020 seconds (or longer) turn off the power supply record the last amperage value and the time. Now you retrieve the anode from the cell, dry it as before by immersing it in alcohol and allowing it to dry on a paper towel, and weigh it. If you wipe the anode you will remove copper from the surface and invalidate your work! If you can, repeat the experiment using the same electrodes. Sample Calculation The following measurements were made: Anode mass lost: 0.3554 grams (g)Current(average): 0.601 amperes (amp)Time of electrolysis: 1802 seconds (s) Remember:One ampere 1 coulomb/second or one amp.s 1 coulombThe charge of one electron is 1.602 x 10-19  coulomb Find the total charge passed through the circuit.(0.601 amp)(1 coul/1amp-s)(1802 s) 1083  coulCalculate the number of electrons in the electrolysis.(1083 coul)(1 electron/1.6022 x 1019coul) 6.759 x 1021  electronsDetermine the number of copper atoms lost from the anode.The electrolysis process consumes two electrons per copper ion formed. Thus, the number of copper (II) ions formed is half the number of electrons.Number of Cu2  ions  ½ number of electrons measuredNumber of Cu2  ions (6.752 x 1021  electrons)(1 Cu2  / 2 electrons)Number of Cu2  ions 3.380 x 1021  Cu2  ionsCalculate the number of copper ions per gram of copper from the number of copper ions above and the mass of copper ions produced.The mass of the copper ions produced is equal to the mass loss of the anode. (The mass of the electrons is so small as to be negligible, so the mass of the copper (II) ions is the same as the mass of copper atoms.)mass loss of electrode mass of Cu2  ions 0.3554 g3.380 x 1021  Cu2  ions / 0.3544g 9.510 x 1021  Cu2  ions/g 9.510 x 1021  Cu atoms/gCalculate the number of copper atoms in a mole of copper, 63.546 grams.Cu atoms/mole of Cu (9.510 x 1021  copper atoms/g copper)(63.546 g/mole copper)Cu atoms/mole of Cu 6.040 x 1023  copper atoms/mole of copperThis is the students  measured  value of  Avogadros  number!Calculate percent error.Absolute error: |6.02 x 1023  - 6.04 x 1023  | 2 x 1021Percent error: (2 x 10 21 / 6.02 x 10 23)(100) 0.3 %

Personality Testing For Select Employees - 1710 Words

Organisational Behaviour MGMT1135 Assignment 2 By Henry Mony de Kerloy Introduction â€Å"Personality refers to the relatively stable pattern of behaviours and consistent internal states that explain a person’s behavioural tendencies.† (Mcshane, Travaglione, 2005) In the past the use of personality testing to select employees was looked down upon and thought to not be an accurate predictor of an employee’s job performance, however with increased confidence in how personality is defined (The Five Factor Model) experts are starting to recognize the usefulness of personality tests in predicting work performance (Hurtz, Donovan, 2000). Agreeableness, which is a part of the Five Factor Model, is an important trait in employees ability to interact†¦show more content†¦Review What is Agreeableness? The Five Factor personality Model (FFM), of which Agreeableness is a part, is a, â€Å"hierarchical organization of personality traits in terms of five basic dimensions: Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness to Experience.† (McCrae, John, 1998) The FFM is a widely used model for defining the dimensions of personality. In this essay I will be focusing in on the dimension of Agreeableness and the effect of how agreeable an employee is affects their performance in a job, which has a lot of interpersonal interactions. Traits commonly associated with Agreeableness â€Å"include being courteous, flexible, trusting, good-natured, cooperative, forgiving, soft hearted and tolerant.† (Barrick, Mount, 1992) Is Agreeableness indicative of high job performance in a customer service setting? Employees in customer service jobs and jobs where people have to deal with social interactions, such as retail businesses, have to be able to get on with the customer and have a lot of interpersonal interactions with them. If they want to be good at their job and have a high job performance they will have to deal with the wide range of different customer personalities, all the while doing it in a warm, courteous and good natured way. All of which are traits of a person who is highly agreeable. Thus, â€Å"Agreeableness will be positively related to performance in jobs involving interactions with others.† (Mount, Barrick,

What are the key issues deciding to purchase for zara internally and externally free essay sample

Speed and responsiveness to Market, Zara has changed the way clothing industry works where deigning, production and delivery to the retailers requires period of six months. The design and distribution cycle of the company takes just 10-15days in the whole process. Zara’s speed to market in product development exceeds the capabilities of its competitors. This in itself provides additional value to stakeholders, customers, and stores in producing quality clothing at affordable prices. The proximity of their manufacturing and operational processes allows Zara to maintain the flexibility necessary to design and produce over 12000 new items annually. This capability allows Zara to achieve their strategy of expedited response to consumer demand. The process of obtaining market information and relaying it to design and production teams expedites product development by shortening the throughput time of their products from design to store. Dependability Due to Zara’s ownership and control of production, they ensure timely delivery and service. We will write a custom essay sample on What are the key issues deciding to purchase for zara internally and externally or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page Although most of their stores run out of stock, signifying that they have low dependability in terms of product availability, another perspective of dependability in terms of keeping to date with fashion is achieved. Quality Zara brand has been said to be ‘synonymous with the cutting edge of fashion at affordable prices. ’ (123helpme. com, 2008) Another Quality advantage is the added sense of quality to the product as the tags would be labelled with â€Å"made in Europe† rather than â€Å"made in China† due to Zara’s trade-off between Low labour costs in Asia and operational efficiency. Flexibility: Designers (of average age 26) draw the design sketches then discuss it with market specials and planning procurement staff illustrating a flexibility of ideas generation and on the other hand the huge number of designs reflects the ability to meet almost all the fashion requirements by customers of all ages (up to 55). This adaptive model rather than traditional merchandising is very different from its competitors. Many competitors rely on a small elite design team that plans both design and production needs well in advance. Stores have little autonomy in deciding which products to display or put on sale because Headquarters plans accordingly and ships quantities as forecasted. Zara owned many of the fabric dying, processing and cutting equipment that provided Zara added control and flexibility to adopt new trends on demand. The added flexibility helped Zara on two fronts: shorter lead times and fewer inventories. (OPPapers. com, 2009) Cost: Zara produces most of its products in Europe. Compared to their competitors, they outsource very little to Asia [6] . Though the cost of production in Spain is 17-20% more expensive than Asia, Zara does have a competitive advantage over its competitors in regards to operations. Though there is a cost advantage in their approach in regards to labour, the lack of flexibility in changing orders based on current trends hinders their operational efficiencies. Inventory costs are higher for competitors because orders are placed for a whole season well in advance and then held in distribution facilities until periodic shipment to stores. Lower inventory cost is a key sustainable advantage as it enables Zara to manufacture and sell its products at cheaper prices. A case study analysis of Zaras Operations Strategy Zara is the largest division and flagship brand of the Spanish retail group Inditex [1] . It sells up-to-the-minute ‘fashionability’ at low prices, in stores that are clearly focused on one particular market. (Slack, Chambers, Betts, Johnson, 2006) The first store opened by accident in 1975 due to a large pyjamas order cancellation. This typically can be said to be an emergent strategy as the Zara store today was not an intended strategy. [2] As described in a case study of Zara’s supply chain, the company is vertically integrated, controlling most of the processes in its supply chain. On the average, 50% of its products are manufactured in Spain, 26% in the rest of Europe and 24% in Asian countries. Zara outsources products of high labour intensive processes but maintains in-house capital intensive processes, protecting knowledge and know-how. It takes less than two weeks for a skirt to get from Zaras design team in Spain to a Zara stores in any part of the globe, as much as 12 times faster than the competition. And with shorter lead times, Zara can ship fewer pieces, in a greater variety of styles, more often and they can more easily cancel lines that dont sell as well, avoiding inventory backlogs. (Upadhyay, 2009) Zara’s quick response capacity is made possible by the fact that it controls the 3 main stages of its operations that define the competitive edge of the company: design, manufacturing and distribution. This strategy is embraced to focus on the operations which can enhance cost efficiency while boosting service delivery and value proposition. As a fashion imitator, Zara ‘s priority was to focus its attention on understanding the dynamic fashion trends, aligning these changes to meet its customers’ wants rather than on promoting predicted seasons trends via fashion shows and similar channels of influence, which the fashion industry traditionally used. Other production activities are completed via a network of about 500 subcontractors in close proximity to Zara’s operations at La Coruna. Mr. Ortega the CEO of the Inditex, the parent company of Zara, once said that the secret to retail success is to have five fingers touching the factory and five touching the customer. (Slack Lewis, Operations Strategy, 2008) This paper uses the models and frameworks of the Operations Strategy module to describe analyze how Zara’s operations strategy led to a sustainable competitive advantage in the global apparel industry. 2 Introduction Zara is the flagship brand of the Spanish retail group, Inditex SA, one of the super-heated performers in a soft retail market in recent years. The first Zara shop opened its doors in 1975 in La Coruna, GaliciaSpain, the city that saw the Groups early beginnings and which is now home of its central offices. Its stores can now be found in the most important shopping districts of more than 400 cities in Europe, the Americas, Asia and Africa. With year-on-year sales increasing at around 25% over the last 5 years, it has become one of the world’s fastest growing retailers. As of late last year, Zara had 350 shops in Europe, 18 in the Middle East, 52 in the Americas and five in Asia. With roughly 40% of Inditex shops, Zara brings in about 80% of the groups revenue.(Zara founder makes a mint, 2001) As retailers like Marks Spencer and Gap join retailers in reporting falling profits, what makes a Spanish retailer to announce profit and Growth and assume this post as forthcoming leader in the fashion retail industry? What Ortega, the founder of Inditex, saw that others didn’t see? What is Zara Business Model? What is Z ara strategy? What are the factors behind the success of Zara? How scalable its model is? What are the challenges? How Zara would cope with the challenging environment of fashion retail business faced nowadays by the leaders in this industry? Amancio Oretga thought that customer would regard clothes as perishable commodity – no different from yogurt or bread- to be consumed rather than stored in closets, and has gone about building a retail business that provides â€Å"freshly baked clothes â€Å". By Focusing on apparel as product for consumption Zara compete on speed. This business is all about reducing response time. In fashion stock is like food it goes bad quickly. So, Zara concentrates on three winning formulas: Offering fashionable variety with limited supply at affordable price (cost) with a quick response to market.(Devangshu Dutta 2002) 3- Zara Vertical integrated Supply Chain An efficient supply chain is becoming more and more key success factor for companies. Henry Ford assembly line was the event of mass industrial production. Is supply chain management the new differentiation for companies? According to McMillan and Mullen (Operations Management Vol-2, 2002), â€Å"the purpose of SCM is to integrat e all tasks associated with the bi-directional flow of materials, information and finance into organized, coherent, managed processes in order to provide end-to-end management and control. †

Role of Odp free essay sample

The role of a qualified operating department practitioner is to provide high standards of peri-operative care to patients whilst also giving skilled support to surgeons, anaesthetists and/or theatre nurses. ODP’s need a broad knowledge and skill base that includes excellent communication skills, management skills and teamwork skills, as they are involved with the assessment, delivery and evaluation of peri-operative care. There are three phases to peri-operative care; the anaesthetic phase, the surgical phase and the recovery phase. Within each phase there is a different role for the ODP to undertake. In the anaesthetic phase ODP’s assist in the care of the patient prior to surgery ensuring the safety and comfort of the patient at all times. They also prepare the anaesthetic equipment and room and assist the anaesthetist throughout. In the surgical phase ODP’s work as part of the operative team in a few roles that include the â€Å"scrubbed† role, infection control, wound management and the application of the aseptic technique. We will write a custom essay sample on Role of Odp or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page In the process of the surgical phase ODP’s work in the â€Å"scrubbed† role preparing all the equipment and necessary instruments needed for the procedure, working with the surgeon to assist in the procedure providing all the correct instruments and materials. They must also ensure health and safety throughout the surgical procedure and to ensure that all instruments, equipment and swabsare are accountable. ODP’s prepare the theatre and the equipment whilst also acting as a link between the surgical team and other parts of the hospital. In the recovery phase ODP’s are involved in all aspects of patient care in the recovery unit, including monitoring, supporting them and providing treatment until the patient has recovered. ODP’s then assess the patient to evaluate whether they can return to the ward. They then must evaluate the care given during all the three stages of peri-operative care. (NHS careers, 2012). ODP’s tend to have a flexible, adaptable approach to the role and have a caring nature with good communication and teamwork skills as they tend to work with a variety of people like porters, ward nurses, healthcare support workers, theatre nurses, anaesthetists, surgeons, other ODP’s and patients from all walks of life. The role can have its challenges as you are dealing with patients who can become very stressed and/or emotional when coming to theatre and everyone is different so react differently, ODP’s need to be able to deal with all situations quickly and effectively in a caring and professional manner. In the role ODP’s can face other problems that are caused by language barriers and/or communication problems that they will need to overcome, plus more importantly, emergency situations can happen any time and ODP’s need to react quickly and professionally to ensure the safety of the patient and other’s around. The role can be emotionally and physically challenging but it does have its advantages; the role is very diverse throughout with support in all areas. It can involve a good progression up to team manager or theatre manager level with good rates of pay and professional development. As generally with any hospital role this involves shift patterns that can include early (8am-5/6pm), late (12 noon-9pm) and night shifts (9pm-8am), which are around 37. 5 hours a week. (Day in the life, 2012).