Time dispersion parameters

When a signal is transmitted, this signal can endure a deformation caused by contemplations and scattered extension waies in the wireless channel, and these phenomenons cause that an indistinguishable signal arrives at different times at its finish. These different times are due that to the signal arrives via multiple waies and in different incident angles. The clip difference between the arrival minute of the first multipath constituent and the last 1 is called hold spread. In order to compare different multipath channels and to develop some general design guidelines for wireless systems, some parametric quantities are used to quantify the multipath channel. Some of these multipath parametric quantities are the average extra hold, rms delay spread, and maximal extra hold, and can be determined from a power hold profile. However, the mean extra hold and the rms delay spread are often used to quantify the clip diffusing belongingss of broad set multipath channels.Mean Excess DelayThe Mean Excess Delay is the first minute of the power hold profile ( PDP ) and is defined byRMS Delay SpreadThe root-mean-square ( RMS ) hold spread is likely the most of import individual step for the hold clip extent of a multipath wireless channel. This parametric quantity calculates the standard divergence value of the hold of contemplations, weighted relative to the energy in the reflected moving ridges. This parametric quantity can be considered like the square root of the 2nd cardinal minute of the power hold profile and is defined by We must take into consideration that these holds are measured comparative to the first noticeable signal arriving at the receiving system at = 0, and their equations do non trust on the absolute power degree of P ( ) , but merely the comparative amplitudes of the multipath constituents within P ( ) .Maximum Excess Delay ( X dubnium )The maximal extra hold ( X dubnium ) of the power hold profile is defined as the clip hold value after which the multipath energy falls to X dubnium below the maximal multipath energy ( non necesarily belonging to the first arriving constituent ) . It is besides called extra hold spread, but in all instances must be specified with a threshold that relates the multipath noise floor to the maximal standard multipath constituent. The values of these clip scattering parametric quantities besides depend on the noise threshold used to treat P ( ) , and if this noise is set excessively low, so the noise will be processed as multipath and therefore doing the parametric quantities to be higher.EnvironmentCoherence BandwidthCoherence bandwidth is a statistical step of the scope of frequences over which the channel can be considered â€Å" level † . If we define Coherence Bandwidth ( BC ) as the scope of frequences over which the frequence correlativity is above 0.9, so If we define Coherence Bandwidth as the scope of frequences over which the frequence correlativity is above 0.5, so The coherency bandwidth of the channel gives a good indicant about the frequence fluctuations of the channel in relation to the bandwidth of the familial signal. We can hold two different instances, depending on this bandwidth. If a signal with a bandwidth larger than Bc is transmitted through the channel, it will be capable to frequency selective deformation. The channel will be, in this instance, referred to as a frequence selective attenuation channel. However, if the signal transmitted has a bandwidth well less than Bc, it will see amplitude fading merely with no deformation since the channel features will be the same all over the spectrum of the signal. In this instance the channel is referred to as a frequence non-selective ( level ) melting channel.

Barilla & Harvard Business School.

Nowadays, manufacturing and services firms face growing challenges to increase profit margins amidst increasingly fiercer competition. Under such circumstances, industry analysts and supply chain experts suggest manufacturers and service providers to promote more effective supply and demand planning, management, and execution as the means to unlocking significant gains in margins. By definition, Search CIO (2007) defines SCM as the management of information, materials, and finances along a chain of process from suppliers to manufacturers and then from manufacturers to customers.The interests in the discussion of supply chain management occur since it relates to costs reduction in all aspects of business process especially regarding the inventory reduction that suggests manufacturer produce goods when needed. The situation highlights that supply chain management will enhance lead time (time-to-market) of particular products, thus enabling all parties within an organization to manage t heir resources more effectively. Concerning the issue, this paper will describe supply chain management issue in Barilla spA, an Italian manufacturer that sells their products to its retailers mainly via third-party distributors.The competition in the market has caused unfavorable situation for Barilla during late 1980s when the company faced unpredictable demands from its distributors. 2. What are the reasons for the increase in variability in Barilla’s supply chain? Barilla maintains separate supply chain because the company has two general products: fresh and dry products, which required special treatment. In this situation, fresh products is mainly purchased from the two central distribution centers (CDCs) by independent agents who further channeled the products into 70 regional warehouses across Italy.Meanwhile, about two third of dry products are sold at supermarkets. Figure 1 explains the supply chain systems for Barilla. 3. How can Barilla cope with the increase in va riability? In order to succeed the distribution system, Barilla is known to practice the replenishment strategy, which describes an agreement between Barilla and their supplier to share the data about frequency and inventory levels to match Barilla demands (About. com, 2008).By delivering the products under the agreement with suppliers, Barilla is able to support their Just in time (JIT) distribution system, which is considered to be the optimum strategy to accomplish the company’s mission of having increased customers satisfaction. 4. What is the impact of transferring demand information across the supply chain? By sharing information between Barilla and their suppliers, there are positive impacts since the combination of JIT and replenishment strategy supports the demand fluctuations, reduced inventory level at warehouse, decreased stock-out levels etc.5. Can the Vendor Managed Inventory strategy solve the operational problems faced by Barilla? In Vendor Managed Inventory ( VMI) strategy, the suppliers have greater responsibility over the supply since they are required to determine the delivery frequency and inventory levels in order to maintain the agreed stock levels in warehouses. In addition, the practice of this system also helps Barilla to track out-of-stocks and other performance data, previous years’ sales history and trends.Therefore, the practice of Vendor Managed Inventory (VMI) has solved the operational problems at Barilla. 6. How can the supply chain meet conflicting goals of different partners and facilities? In order to avoid the conflict between different partners and suppliers of Barilla, the company must ensure that the implementation of Just in Time system will help the maintenance of satisfaction in services, inventory levels, and stock-out levels and others in which each supplier has taken part of the system.In addition, Barilla must also ensure that within implementation steps, the use of EDI to deliver the inventory infor mation is the same among suppliers so the reliability can be secured and the compatibility level can be reached. Reference: About. com. (2008). Reduce Inventory with these 3 Supplier Partnership Strategies. Retrieved September 7, 2008 from http://logistics. about. com/od/inventoryoptimization/a/supplier_partnr. htm Hammond, Janice H. (2008). Barilla SpA (A). Harvard Business School.O’Brien, Kevin and Brian Springman. (2004). Optimizing Supply Chains, Understanding Demands. Retrieved September 7, 2008 from http://www. crmbuyer. com/story/35892. html Search CIO. (2007). Supply Chain Management. Retrieved September 7, 2008 from http://searchcio. techtarget. com/sDefinition/0,,sid19_gci214546,00. html YAO Kao-hua, LIU Chang-chuan. (2006). An Integrated Approach for Measuring Supply Chain Performance. Journal of Modern Accounting and Auditing. Vol. 2, No. 10

Synthesis of Salicylic Acid and Potentiometric Determination of Its Purity and Dissociation Constant

Synthesis of Salicylic Acid and Potentiometric Determination of its Purity and Dissociation Constant ————————————————- Abstract The purpose of the study is to synthesize salicylic acid from the ester, methyl salicylate, and determine the acid’s dissociation constant and purity. The ester was converted to salicylic acid by base hydrolysis. The products were refluxed and recrystallized, to ensure maximum purity, and filtered, dried, and weighed. The melting point of the product was determined using a Fischer-Johns melting point apparatus. The acid then dissolved in separate beakers with 95% ethanol and water and titrated with 0. 050 M NaOH, previously standardized with potassium hydrogen phthalate, through potentiometric titration. The pH after addition of base was measured and plotted against the volume of titrant added using three different plots. Results show a 61. 0% yield and the melting point differed from the theoretical by a range of 3. 11-6. 83%. The pKa calculated was 2. 865, differing from the literature value of 2. 98, by 3. 86%. The theoretical purity of the sample was 100. 0%, which differed with the experimental one by 1. %; the experimental purity is 101. 7%. Potentiometric titration proves to be adequate in the determination of the acid dissociation constant and purity of a sample. Aside from that, the synthesis proved adequate given the high purity of the product. ————————————————- Keywords : acid dissociation constant purity melting point ester INTRODUCTION Potentiometric methods of analysis are based on measuring the potential of electrochemical cells without drawing much, appreciable current. For centuries, potentiometry has been used to locate the endpoint in most titration set-ups. Skoog, et al. , 2004). Potentiometric methods offer a myriad of advantages, its main advantage being its low operational costs. Voltmeters and electrodes are, generally, far cheaper than most modern scientific instruments. Models suitable for direct potentiometry in field work, away from the laboratory, are inexpensive, compact, and easy to use. Essentially nondestructive of the sample, i. e. , insertion of the electrode does not drastically change the composition of the test solution (except for the slight leakage of electrolytes from the reference electrode), electrodes are relatively free from interferences. Stable potential readings are attained fairly rapidly and voltages are easily recorded as functions of time. Finally, the wide range of analyte activities, over which some of the available indicator electrodes exhibit stable, nearly Nernstian responses, represents an important advantage (Day and Underwood, 1991). Potentiometric titrations involve measurement of the potential of a suitable indicator electrode as a function of titrant volume. This indicator electrode is speecific to the hydronium ion, H3O+. It offers adavantages over direct potentiometry in that it is not dependent on measuring absolute values of Ecell. This is due to having the measurement based on the titrant volume that causes a rapid change in potential near the equivalence point. This makes the process relatively free from the juction potential uncertainties as this potential remains approximately constant during the titration process. Instead, the titration results depend heavily on having a titrant with accurately known concentration. The instrument merely signals the endpoint and behaves like a regular chemical indicator. Aside from that, the reference electrode potential need not be known. Most importantly, ionic strength effects are not important in the titration procedure because the result is analyte concentration, even if the electrode responds to activities. The dissociation of a weak monoprotic acid is given by the equation HA – H+ + A– (1) [H+][A–] [HA] where HA is the monoprotic acid, and A– is its conjugate base. The corresponding equilibrium constant for this acid dissociation is defined as Ka = (2) Ka[HA] [A–] which, when seeking to find [H+], rearranges to [H+] = (3) Prior to the equivalence point, before any titrant was added and the analyte is the only species present in solution, the pH of the system is calculated from the concentration of that analyte and its dissociation constant. In the case where a weak monoprotic acid is being titrated with a strong base, subsequent addition of the titrant will cause a reaction to occur between the acid and the base. HA + OH– > H2O + A– (4) The presence of the acid and its conjugate base in solution will cause the formation of a buffer solution, which are solutions that resist a drastic change in pH, should a strong acid or base be added to the system. At these points, the slope of a constructed titration curve is at its minimum. This is the pre-equivalence point. There is a point during the pre-equivalence point region wherein both the acid and its conjugate base are present in equal amounts. This occurs when half of the acid has been neutralized, or when the titration is at the half-equivalence point. At this point, the buffering capacity of the system is at its maximum. Aside from that, simplifying Eq. 3 at this point by inspection, the [H+] is equal to that of the Ka. Taking the negative of the logarithm of both sides, one will be able to get the relation pH = pKa (Skoog, et al. , 2004). Thus, the dissociation constant may be computed through determining the pH at half-equivalence point. This experiment will use salicylic acid as the analyte. Salicylic acid, Fig. 1. Salicylic acid is a weak monoprotic acid, capable of releasing the acidic hydrogen connected to the –COOH group. The hydrogen of the phenol group is hard to release because the oxygen is stabilized by resonance. Salicylic acid is a naturally occuring substance, usually produced by plants. It is found mainly in the willow's leaves and bark. The pure acid possesses several useful medicinal properties. It is an antipyretic (fever reducer), analgesic (pain reliever) and anti-inflammatory (swelling reducer). However, pure salicylic acid makes for an extremely unpleasant medicine. Salicylic acid contains two acidic functional groups, the phenolic (C6H5OH) and the carboxylic acid (RCOOH) groups. These groups cause the acid to be an irritating substance that burns the delicate lining of the mouth, throat, and stomach, hence its esterification to acetylsalicylic acid or aspirin, before ingestion as analgesic (Reed College, 2009). Esterificaton is the process by which a carboxylic acid is transformed to an ester. Esters are organic compounds that are derived usually by reacting a carboxylic acid and an alcohol. The general formula for esters is with the RC=O group derived from the parent carboxylic acid, and the –OR’ group from the parent alcohol. The mechanism for the reaction of the alcohol and carboxylic acid to form the ester is as follows: Fig. 2. Mechanism of Esterification from a Carboxylic acid RCOOH and alcohol R’OH Esters may also be synthesized by reacting the carboxylic acid with other reagents such as SOCl2 to form the acyl chloride, which will then be treated with an alcohol in pyridine, to esterify it. Esters are among the most widespread of all naturally occuring compounds. Many esters are pleasant-smelling liquids that are responsible for the fragrant odor of fruits and flowers. For example, methyl butanoate is found n pineapple oil and isopentyl acetate is a constituent of banana oil. The ester linkage is also present in animal fats and other biologically important molecules. The chemical industry also uses esters for a variety of purposes. Ethyl acetate, for example, is commonly used as a solvent while many dialkyl phthalates are used as plasticizers to keep polymers from being brittle (McMurry, 2004) . Methyl salicylate is produced by many plants. It was first isolated from wintergreen leaves, Gaulthea procumbens, and is commonly known as oil of wintergreen. Fig. 3. Methyl salicylate An ester of salicylic acid and methanol, it masks one of the acidic hydrogens in salicylic acid by replacing it with a methyl (CH3–) group. Hence, it is a relatively unreactive compound that does not release salicylic acid efficiently into the body. It is, therefore, not an effective analgesic, or pain-killer. However, it is added to many products, notably for its fragrance, especially root beer and liniments. In order for it to be activated, methyl salicylate must be converted to salicylic acid by organic synthesis, specifically through saponification, a process not unlike that undergone by animal fats to become soaps (McMurry, 2004). In this experiment, salicylic acid will be synthesized from methyl salicylate by base hydrolysis. Its dissociation constant will also be measured through potentiometric titration. Likewise, the percentage of purity the salicylic acid used in the reaction will be likewise determined. METHODOLOGY In synthesizing salicylic acid, 1. 2 g of sodium hydroxide (NaOH) were dissolved in 7 mL water in a round bottom flask.. Half of a milliliter (0. 5 mL) of methyl salicylate was added to this mixture. The mixture was then efluxed for 15 minutes and cooled to room temperature. One-milliliter increments of 3 M sulfuric acid (H2SO4) were added until the formation of a white precipitate, salicylic acid. Half of a milliliter (0. 5 mL) of the acid was added to ensure complete precipitation of the product. The mixture was then cooled in an ice water bath with a temperature of at most 5 °C for the reaction to subside. The product was then filtered and rinsed with cold water, and recrystallized in wat er. The solids were then filtered on a pre-weighed filter paper and air-dried in the locker. When dried, the solids, along with the filter paper, were weighed and the melting point determined. Two hundred and fifty milliliters (250 mL) of 0. 50 M stock sodium hydroxide (NaOH) solution was then prepared. From this solution, 250 mL of 0. 050 M standard solution was prepared for the titration. This solution was then standardized with 0. 2000 g 99. 95% potassium hydrogen phthalate (KHP) and phenolphthalein as indicator to the pale pink endpoint. Two more trials were done. Three samples of pure salicylic acid were weighed at approximately 0. 000 g and placed in three separate 250-mL beakers. A minimum amount of 95% ethanol was then added to dissolve the acid, and was diluted with 50. 00 mL distilled water. The electrode was first calibrated such that it would relate the developed potential to the pH. At this point, the potential would be measured as pH when increments of the titrant are successively added. The base burette, pH meter, and magnetic stirrer were set up according to Fig. 6. Fig. 6. Potentiometric titration set-up A spin bar was place inside the beaker with the sample solution. The electrode was also positioned such that it would not get hit with the spin bar. The pH of the set-up was first measured prior to addition of base. For the first trial, 1. 00 mL of the titrant was added to the analyte and the pH recorded. This was done until the pH was 11. 50. From there, the equivalence point was approximated based on the volume of the titrant that caused a large change in pH. For the two succeeding trials, 1. 00 mL of the titrant was added to the analyte. At  ±5. 00 mL of the equivalence point, the volume of titrant added was reduced to 0. 0 mL increments. At  ±3. 00 mL and  ±2. 00 mL of the equivalence point, it was further reduced to 0. 20 mL and 0. 10 mL, respectively. The titration contnued beyond 5. 00 mL of the equivalence point using 0. 50 mL of titrant until the pH registered was 11. 00. RESULTS AND DISCUSSION Methyl salicylate reacts with a strong base in the following manner: Fig. 4. Base hydrolysis of methyl salicylate The methoxy group of the e ster is substituted by the hydroxide ion through nucleophilic acyl substitution. The hydroxide attaches itself to the carboxylic carbon. A fast proton transfer from the hydroxide to the methoxy group occurs such that the methoxy gets protonated and leaves the substrate. The sodium ions stabilize the negative charge of the salicylate ion predominantly found near the two oxygens of the ion. The solution was then refluxed to prevent loss of material and to prevent the inclusion of impurities in the product. After cooling to room temperature, 1. 00 mL of 3M sulfuric acid (H2SO4) until salicylic acid starts precipitating as a white solid. To complete the precipitation, 0. 50 mL of the strong acid was added to the mixture. At this point, the salicylate ion is protonated and the final product, salicylic acid, forms through the reaction: Fig. 5. Protonation of the phenolate and carboxylate groups of the salicylate ion The flask containing the precipitate was then doused in cold water to stop the reaction. Cold water was used in rinsing the solid after filtration to wash out impurities that were insoluble in the solvent. The solid was recrystallized in hot water. Dissolving the solids in hot water generally increases the solubility of the substances, hence the solids dissolve along with the soluble impurities. The mixture was then allowed to cool slowly. As the solution cools, the solubility of the compound (and of the soluble impurities) decreases, the solution becomes saturated with the desired compound, and the compound begins to crystallize. Because formation of crystals is a highly selective process that usually excludes foreign molecules, only crystals of the desired compound form. Because the soluble impurities are present in smaller amounts, the solution never becomes saturated with the impurities, so the impurities remain in solution even after the solution has cooled. Removing the solution from the crystals thus removes the solvent and the soluble impurities from the desired crystals. A final rinse of minimum ice water ensures the displacement of the impurities still clinging on the surface of the product (â€Å"Recrystallization,† accessed 6 Sept 2010). After it was recystallized, the solid was filtered again in a pre-weighed filter paper. The filter paper used in filtering the solid weighed 1. 0349  ± 0. 0002 g. The mass of the dried product and the filter paper was 1. 3610  ± 0. 0002 g; this means that 0. 3261  ± 0. 0003 g was synthesized. Theoretically, with methyl salicylate as the limiting reagent, the mass of salicylic acid should be 0. 5400 g. Computing for the %yield, would give 61. 0%. In the determination of the melting point, the observed range of the melting point was 150-156 °C. Comparing with the theoretical value, 161 °C, the relative error lies within the range 3. 11-6. 83%. Therefore, the synthesized salicylic acid has a high purity as exhibited by the magnitude of the relative error. This could justify the %yield given that recrystallization might have caused a loss of material due to the increase of the number of steps involved. It should be noted that in organic synthesis, steps leading to the target molecule do not give 100% yield, hence, increasing the number of steps would decrease the %yield. Aside from that, the low yield could be attributed to the accidental rapid cooling that occurred during the recrystallization process. In a titration curve, there are three important regions: pre-equivalence point, equivalence point, and post-equivalence point. For the titration of salicylic acid with NaOH, the pre-equivalence point is characterized by the dependence of pH on the concentration of salicylic acid. Let salicylic acid be HA; prior to addition of the base, the pH can be calculated by the concentration of HA and its acid dissociation constant, Ka. When the base is added, HA reacts with the hydroxide ion (OH– ) according to the Eq. 4 stated above. Therefore, one has a buffer solution comprised of salicylic acid and salicylate. At equivalence point, all of the acid has been converted into its conjugate base. This base will hydrolyze with water through the reaction A– + H2O > HA + OH– (6) reforming a small portion of the acid. At the equivalence point, the slope of the titration curve is at its steepest. The pH at this point is dependent upon the conjugate base formed and its base dissociation constant, Kb. Beyond the equivalence point, the post-equivalence point, the pH is dependent on the concentration of the excess titrant added. This is because the contribution of the conjugate base is very small and, therefore, negligible compared to that of sodium hydroxide. However, salicylate is still the dominant species of salicylic acid present in solution. A distinction between equivalence point and endpoint should be established when titrating. Skoog, (2004), states that the equivalence point is the point in titration where the amount of titrant added is chemically equivalent to that of the analyte in solution. The endpoint is a point during titration wherein an observable change signals that the amount of titrant added is chemically equivalent with that of the analyte. The endpoint may not necessarily coincide with the equivalence point, especially in neutralization titrations. It may come earlier or later than the equivalence point, depending on the indicator used. This difference pf volume at equivalent and endpoint is known as titration error. In potentiometric titration, no chemical indicator is required. Instead, the endpoint is characterized by the drastic change in pX, measured by the electrode. X may be H3O+, OH–, a cation or anion, or any substance participating in the titrimetric reaction (Day and Underwood, 1991). In this case, the volume of titrant that contributes to the greatest change in pH is the volume required to completely titrate the salicylic acid in solution. Thus, the increments of addition of titrant are narrowed down as the equivalence point is reached because that way, the equivalence point will not be missed. Aside from that, the exact volume of titrant required for complete reaction of the analyte would be detected. Prior to titration and dilution with water, the salicylic acid was dissolved with a minimal amount of 95% ethanol. Salicylic acid is sparingly soluble in water, a polar solvent that can hydrogen-bond with solutes that can hydrogen-bond with its molecules. This is due to the acid having more than 6 carbons increasing its non-polarity, although it has oxygen that can form hydrogen bonds with water (McMurry, 2004). Adding ethanol reduces the polarity of the solvent, facilitating dissolution of the acid. It was noted that some of the acid reprecipitated upon addition of water. Thus, a minimum amount of 95% ethanol was again added to dissolve the acid. In the experiment, the electrode was also not lowered while the bar was spinning as air bubbles would adhere on its surface causing an error in the measurement of pH. Constant stirring is important in potentiometric titrations, as in other types of titrimetric analyses. Stirring is done because it will cause the titrant to react not just with the surface of the analyte where it dropped but with the entirety of the analyte solution. This way, the reaction will go to completion and minimal error will be observed. The volumes used for standardization of NaOH with KHP as primary standard are tabulated in Table 2 in the Appendix. Standardization of sodium hydroxide gave 0. 04633 M NaOH. This value was used in the determination of the percentage of purity (%purity) of the salicylic acid sample. For the determination of the equivalence point volume, three plots were done for each trial. The first plot is the graph between pH vs. volume of titrant. The second is the first derivative plot with which ? pH/? V was plotted against V’, where ? pH and ? V are the change in pH and the volume added between two consecutive readings, respectively, and V’ is the average volume between two consecutive readings. The third plot is the second derivative plot between ? 2pH/? V2 and V†. The ordinate of the graph, ? 2pH/? V2, was obtained by taking the quotient of the difference between two consecutive readings of ? pH/? V, and ? V, whereas V† is the average of the two consecutive readings of V’. Only two trials were done because of the inadequacy of the time. The graphs for the first trial are: a) (b) (c) Fig. 7. Titration Curves for the First Trial. (a) pH vs Vtitrant; (b) ? pH/? V vs V’; (c) ? 2pH/? V2 vs V† MNaOHVNaOH at eq ptFWsalicylic acid Gsample The graph for the second trial may be found at the Appendix. Either of the three graphs of Figs. 7 and 8 may be used in the determination of %purity for each trial. The equation used for determining the %pu rity, specifically for this experiment is %purity = x 100 (7) Thus, the volume of titrant used at equivalence point is required for the calculation. The interpolated values of the volume at equivalence point are tabulated in Table 3 in the Appendix. Calculation of the mean %purity is 101. 7%, having an error of 1. 7%, as the theoretical value is 100. 0%. The pKa is based on the pH at half-equivalence point by virtue of the derivation of Eq. 3. Onle Figs. 7a and 8a may be used for the determination of pKa as the other four do not directly give the pH at each point. The interpolated values for the pH at half-equivalence point is tabulated at Table 3 in the Appendix. The experimental pKa is 2. 865. Therefore, the Ka of the acid, given Ka = –log[Ka] (7) or Ka = 10–pKa (8) is 1. 3646 x 10–3. The theoretical pKa is equal to 2. 98. Thus, the pKa value gave rise to a 3. 86% error. Statistical analysis of the results shows the following results: Table 1. Statistical Analysis of the Results | Range| Standard Deviation| %purity| 15. 7%| 11. 1%| pKa| 0. 21| 0. 148| | Relative Standard Deviation (RSD), ppt| Confidence Int ervals (95% confidence)| %purity| 109. 1| 101. 7  ± 99. 7 %| pKa| 51. 8| 2. 865  ± 1. 334| The RSD of %purity is relatively large such that the values have low precision. Aside from that, the confidence intervals for the mean is also large such that it almost has the same order of magnitude as that of the mean. This means that the mean exhibits very low accuracy. With regards to the pKa, the RSD showed a low value, only 51. 8 ppt, implying high precision amongst the values. On the other hand, the mean value shows low accuracy because of the magnitude of the confidence intervals. These errors could be attributed to the number of trials. Due to inadequate time, the group was only able to do 2 trials, one less than the prescribed number of trials. CONCLUSIONS The experiment aimed at synthesizing salicylic acid from methyl salicylate and determining the acid dissociation constant Ka of the acid along with its purity. Organic synthesis provided a 61% yield of the acid, a relatively low yield. However, the purity of the acid can be classified as high due to the observed melting point range’s precision with the theoretical one; the %differenceis only 3. 11-6. 38%. The results of the potentiometric titration show that the salicylic acid used was 101. 7% pure, a value greater than the purity, which is 100%. The Ka, expressed as pKa, obtained was 2. 865, 0. 035 units less than the theoretical value, which is 2. 98. Though the %differences are low, the accuracy of the computed values is questionable given that the confidence intervals for the %purity and pKa are  ± 99. 7 and  ± 1. 334, respectively. These errors can be attributed to the number of trials done, which is two, due to the slow stabilization of the pH meter readings that resulted in a long period of titration. Thus, it can be concluded that potentiometric titration is an effective way of determining the acid dissociation constant of a sample. It is recommended that a better pH meter be used in the measurement of the pH and that solutions used be titrated immediately. REFERENCES [1] Day, R. A. and A. L. Underwood. (1991). Quantitative Analysis. Sixth Edition. Prentice Hall, Inc. , USA. [2] â€Å"Experiment 3: Synthesis of Salicylic Acid from Oil of Wintergreen (Methyl Salicylate). † Laboratory Reference Manual Chemistry 201/202. Reed College. Accessed 6 September 2010 ;http://academic. reed. edu/chemistry/alan/ 201_202/lab_manual/Expt_salicylic_acid/background. html; [3] McMurry, J. (2004). Organic Chemistry. Sixth Edition. Brooks/Cole – Thomson Learning, CA, USA. [4] †Recrystallization. † University of Massachussetts. Accessed 6 September 2010 ;http:// www. chem. umass. edu/~samal/269/ cryst1. pdf; [5] Skoog, D. A. , D. M. West, F. J. Holler, S. R. Crouch. (2004). Fundamentals of Analytical Chemistry. Eighth Edition. Brooks/Cole – Thomson Learning, CA, USA. APPENDIX Gfilter paper = 1. 0349  ± 0. 0002 g Gfilter paper and dried product = 1. 3610  ± 0. 0002 g Gdried product = 0. 3261  ± 0. 0003 g %yield = 61. 0% Observed melting point range: 150-156 °C %difference = 3. 11-6. 83% 1 ° standard used;: potassium hydrogen phthalate (KHP) purity = 99. 95% Table 2. Standardization of NaOH Trial| Mass of KHP, g| Vtitrant, mL| Molarity, M| 1| 0. 2030| 21. 30| 0. 04664| 2| 0. 2175| 23. 00| 0. 04628| 3| 0. 2043| 21. 70| 0. 04608| Average Molarity, M| 0. 04633| Table 3. Sample Analysis Trial| Gsalicylic acid, g| Vtitrant at eq. pt. , mL| % purity| pH at half-eq. pt. (pKa)| 1| 0. 11 25| 16. 50| 93. 86| 2. 76| 2| 0. 1031| 17. 65| 109. 6| 2. 97| 3| -| -| -| -| Average pKa = 2. 865 Average %purity = 101. 7% Plot of the Second Trial: (a) (b) (c) Fig. 8. Titration Curves for the Second Trial. (a) pH vs Vtitrant; (b) ? pH/? V vs V’; (c) ? 2pH/? V2 vs V†

Marketing Audit Article Example | Topics and Well Written Essays - 500 words

Marketing Audit - Article Example Demographics can provide such opportunities as new customers, increased sales, and increased variety of customers, which all point to the increase of sales and productivity. Threats can also occur such as customers moving away, and customers developing other tastes, because of interaction (Cayla & Arnould, 2008). The economy has increasingly become weak, and, as a result, margins keep on falling and so does asset values. Because of these economic difficulties, the company has faced number financial challenges though it remains profitable. To deal with these financial problems, the company is planning to close about 20 of its stores that are underperforming so as o cut costs and save money (Fortune 500 List of Best Companies, 2009). It is clear that with the current financial problems and challenges with the environment, the availability of the company’s raw materials is going to go down with costs increasing. The costs of energy are also likely to increase because of the same challenges. There have been few, if any, complains about the role of the company in conservation and pollution. In fact, the company has been widely recognized for its initiatives in taking care of the environment and in sustainability. The company has come up with a number of goals to fulfill by the end of 2012 to ensure conservation and sustainability. In addition to this, the company also utilizes a carbon footprint, sustainable foods, reusable bags, zero waste, and conservation initiatives to ensure that the company does little damage to the environment (Fortune 500 List of Best Companies, 2009). There have been major technological innovations in today’s global market, and in the grocery industry. For example, there are new technologies for packaging, for eliminating waste, for ensuring green initiatives, and for production and manufacturing. The company

Christian METAPHYSICS Essay Example | Topics and Well Written Essays - 500 words

Christian METAPHYSICS - Essay Example But that which is called secondary and extrinsic is any effect whether positive or negative, which so results, from the union of form with its subject that it may be adequately distinguished from or remain extrinsic to the form, e.g. the driving out of cold from the water (Runes). God is the highest, ultimate being, assumed by theology on the basis of authority, revelation, or the evidence of faith as absolutely necessary, but demonstrated as such by a number of philosophical systems, notably idealistic, monistic and dualistic ones (Runes), and interpreted by those who do not support theological assumptions to be an intellectually useless assumption, which some find emotionally satisfying (Maartensz). Supersensible refers to realms which are beyond the range of what is perceptible by the five senses; not belonging to the experienceable physical world. Heaven is a supersensible realm (definition-of.net). Rudolf Steiner claimed two portals to supersensible experience and knowledge: nature and mysticism (Steiner). Based on the assumptions that reality is socially constructed, the primacy of subject matter, the emic point of view, and the understanding that variables are complex, interwoven, and difficult to measure, it is an inductive process whereby the personally involved, partial and empathic researcher serves as the primary research instrument, ends with hypotheses and grounded theory, seeks pluralism and complexity in naturalistic observation and participation, searches for patterns in experience, paying attention to emergence and portrayal, makes minor use of numerical indices, and does descriptive write-up. The purpose is contextualization, interpretation, and understanding actors’ perspectives (Del Siegle). Based on the assumptions that facts have an objective reality, the reliability of an etic point of view, the primacy of method, and the identification and measurability of

Equity and trust, Case Study. Case-Barclays Bank v Quistclose (1970) Essay

Equity and trust, Case Study. Case-Barclays Bank v Quistclose (1970) AC 567 - Essay Example 2. Facts of the case. Quistclose lent money to a company Rolls Razor Ltd for a specific purpose of payment of dividends to its shareholders at a time when the company was having overdrawn facilities from Barclays Bank. Eventually, Quistclose went into liquidation when Quistclose sought to recover the money it lent lying in a separate account meant for that purpose, with the dividends remaining unpaid. Barclays Bank, which held that money of the customer Rolls Razor in a separate account. The bank contended that the funds lying in that account should be set off against the company’s overdraft account since the funds belonged beneficially to the borrower company.3 The events prior to the insolvency of Rolls Razor Ltd need to be examined. The company had earned a considerable profit for the year 1963 as per the audited statement and an interim dividend of 80 % that had already been paid. On 14th May 1964, the company decided to pay the final dividend of 120 % that worked out to ? 209,719 8 s 6d net of tax deduction. As it had no liquid resources and its overdraft with Barclays Bank had reached a level of ? 485,000 against the limit of ? 250,000, the bank informed the company its inability to meet its requirement of funds for the payment of final dividend. In the AGM of the company held on 2nd July 1964, payment of final dividend of 120 % was approved. The company managed to obtain a loan of ? 209,719, 8 s and 6 d from Quistclose Investments Ltd to meet its commitment of dividend payment on condition that the payment would only be used for the payment of the said dividend amount. Since the cheque was drawn on Barclays Bank, where the lender was having its overdraft account, it opened an Ordinary Divided No 4 account and credited the proceeds of the cheque received from Quistclose Investments Ltd on 17th July 1964. The company could not raise further resources, and it decided to put the company into voluntary liquidation on the same day with due notice to the bank, which then amalgamated all the accounts of the borrower company except the dividend No 4 account. On 5th August 1964, Quistclose demanded repayment from the borrower without any notice to the bank. When the resolution for liquidation was made on 27th August 1964, bank set off the balance in dividend account No 4 against the money owed by Rolls Razors Ltd in part. This led to the Quistclose’s demanding the bank for repayment of the money appropriated by it.4 3. The issue. Quistclose needed to demonstrate that it had proprietary right over the money as otherwise it was liable to be used to discharge borrower’s overdraft with the bank. In other words, the borrower had held the money as a resulting trust for Quistclose, the lender5. The House of Lords raised two issues: whether there was understanding between the respondents that the amount of ? 209,719, 8 s and 6 d should be held in trust in favour of Quistclose in the event of non-payment of dividend and whether t he bank had notice of such a trust or the bank knew of circumstances that would make the trust binding upon them too. 6 4. The reason for the decision. The House of Lords decided in favour of the lender Quistclose for the reason that such

Criminal Justice Field Case Study Example | Topics and Well Written Essays - 1500 words

Criminal Justice Field - Case Study Example According to her statement, it is quite clear that she was aware of her husband's habit of stealing and indicated that he was doing it in order to support them. Some of the stolen items were also listed in the statement in conjunction with Whitehead's comments on to their ownership (Charlene Marie Whitehead v. Record No. 080775, 2). However, during the trial in Circuit court for the city of Danville, Whitehead denounced everything she had indicated in her statement. She went ahead and claimed that she did not know about Walden's habit of breaking into people's cars. Instead all she knew was that Walden returned with a bunch of things including money. However, during the cross examination, Whitehead admitted that the items brought back to the apartment by Walden were not his. In a contradicting statement, Walden denied having never given Whitehead any stolen item though he pled guilty on the issue. From the issued statements, the trial court decided to bring together Whitehead's forty denunciations to thirty two counts for accepting stolen items from her husband (Charlene Marie Whitehead v. Record No. 080775, 3). In return, the court passed a ruling for each count. Later on, during a sentencing hearing the thirty two counts were reduced to six counts whereby Whitehead was sentenced to five year's imprisonment with four years suspended on each count, for a total of 30 years imprisonment with 24 years suspended. However, the trial court withheld the sentencing on the remaining 26 counts conditioned on 25 years of good behavior. Appearing before another judge in the same court who had been asked by the common wealth to cancel her suspension, Whitehead pled guilty for violating her probation. Consequently, the trial court cancelled its prior suspension and sentenced her to seventeen years, four months of imprisonment with 12 years, four months suspended, for a total of 5 years in addition to her sentences of the new conviction (Charlene Marie Whitehead v. Record No. 080775, 4). The court of appeals confirmed the new convictions and the revocation order in an unpublished opinion indicating that the evidence was adequate to support the court's sentencing. From the information obtained, I tend to disagree with the court of appeal's ruling on Whiteheads case; confirming Whitehead's convictions and the trial court's order of revocation of her probation. This is due to the fact that the common wealth never contended that Whitehead was involved in the actual theft of items or that she received the stolen properties from Walden. Although, there was some contradicting information from Walden regarding her awareness on the stolen items, the court of appeal should have gone a step further and investigate the case. Jeffrey Wayne Rowe v. Record No. 081173 Case It was around 1:30 am on July 9, 2005 when Officer Brian J. Fair of the Virginia Beach police department noticed a truck being driven recklessly. At the moment, he was in his dark blue uniform and was driving his personal car on his way home. He immediately contacted the Virginia Beach police dispatcher requesting for the notification of the incident to the Virginia state police since he believed that the truck driver (Rowe) was drunk. However, he was informed that there were no available state police

Loreal Case Study Example | Topics and Well Written Essays - 750 words

Loreal - Case Study Example Therefore, expansion became and necessity and acquisitions were the means to achieve this. Acquisitions allowed L’Oreal to operate globally, becoming part of the global economy. L’Oreal’s growth strategy was to acquire smaller companies that dealt in cosmetics and other beauty products, after which the acquired products would be assimilated and expanded from within the parent company. Acquisitions meant that the brands could be taken globally, benefiting L’Oreal’s overall brand portfolio. L’Oreal established that they lacked a competitive advantage over American rivals due to their shortage of resources in the cosmetics sector. Therefore, the cosmetics sector was a form of opportunity that would enable them to increase their returns beyond the average mark. Hence, improving the cosmetics portfolio was a major motivation for acquiring foreign cosmetics companies. The adoption began with company developed brands such as Club des Createurs de Beaute, L’Oreal Paris, L’Oreal Professional and Kerastase. L’Oreal adopted Garnier and Lancome Paris in the 1960s. In the 1980’s L’Oreal consumed popular American brands such as Redken, SoftSheen-Carson, Matrix, and Maybelline (which needed reinstallation). L’Oreal also strengthened its French brands by acquiring Ralph Lauren Fragrances, which enabled it to increase its international brand portfolio for customers of various demands and preferences. In the year 2000, L’Oreal acquired Kiehl’s, a company that dealt in high quality, expensive and highly demanded luxurious products. Kiehl’s was deemed a valuable acquisition that added authenticity to L’Oreal’s luxury collection. It also enabled L’Oreal to capture more opportunities in the Consumer Division. Due to its core competencies such as its R&D function and advertising campaigns, L’Oreal was able to reinstate Maybelline and many other smaller acquisitions, enabling it to develop a more attractively priced product that captured

World history Essay Example | Topics and Well Written Essays - 1500 words

World history - Essay Example This two commodities were the most highly commodities. A community’s strength was measured by its ability to produce high quality commodities in the market. Communities which could produce gold, silver or diamond controlled much of the trading markets. This strengthened kingdoms as the disadvantaged communities played second fiddle to these factors. According to Bernier the division of labor was the also significant to human development and creation of leadership figures (316). In his notes Bernier also claims superiority in trade defined the way a dynasty will lead other factors towards a certain direction (316). These leadership traits created what are the common day trade controlling nations. This factor was significant in human development in how trade boundaries and rules were created. Apart from this influence on human development, trade had other ways in which it influenced human development in the 1750. One significant factor on trade was the trade of people. This particular was viewed as an inhumane act that involved strong dynasties and obsolete communities mostly in Africa and South America. However, this trade was significant in the creation of the great civilization that the globe experienced. In an argument by Bernier human trade is responsible for revolution that brought change in human development (316). The author highlights the American Revolution that was greatly initiated by the trade of people from Africa to America. If the trade was not carried out the revolution would have not taken place (Origins of civilisation, 94). Trade had also negative effects in the 1750. There was rampant spread of diseases and constant war fares that were mostly brought by trade disagreements. This was a great hindrance to human development. In words by Bernier diseases and war fares in 1750s was the great enemy to what civilization wanted to achieve (316). In trade in

Power Bases in Leadership Research Paper Example | Topics and Well Written Essays - 2750 words

Power Bases in Leadership - Research Paper Example The paper tells that contemporary complex organizations require proper leveraging of power in order to achieve organizational goals and objectives. As Bal et al. argue, power is the ability to influence others, which leaders use to enhance the performance levels of their followers and to ensure their superiors and peers arrive at the best decisions. The traditional view of power in an organization revolves around the control that individuals at the tip of organizational hierarchy have. However, leaders of different levels within an organization have access to power, whose effective harnessing is key to organizational performance. The importance of power in the organizational setting justifies studies into it and its influences. The very first argument for the importance of power in an organization stems from the historical role of work groups in human history. People have formed groups to execute tasks and accomplish given goals, which forms the basis of an organization. However, the success of such groups is to a considerable extent dependent on the interrelationship of the individuals making the team. This relationship in an organization entails the dynamics between the leader, the followers and the environment created for the group. A wrong miscarriage of power as depicted by a toxic triangle consisting of destructive leaders with susceptible followers in abuse-conducive environments is a recipe for organizational failure. (Padila, Hogan and Kaiser 176). For instance, the leadership within an organization may develop the habit of exploiting the workforce through the power vested in them. Poor pay, overworking and overt and covert forms of vertical violence among other actions from the leadership are manifestations of such abuse of power (Van Vugt, Hogan and Kaiser 178). The motivation, commitment and thus performance of the employees may wane under such circumstances and thus inhibit productivity. In case the productivity remains high, the increased informed consumerism of today’s market may lead to the products of the firm being shunned when it is deemed that they abuse their employees (Crane et al. 287). Thus, how an organization manages its power within the hierarchy determines the direction and success of the organization. Sources of Organizational Power: The important role of power within an organization leads to the need to establish the bases of power; the different types of power and how they are obtained. There are five general bases of power within an organization; legitimate/positional, reward, coercive, expert and personal power (Kinicki and Williams 138). The discussion will focus on each source of power, critically analyzing how such power can be leveraged for the benefit of the organization, pitfalls and recommendations on how to maximize this power successfully. Legitimate/Positional Power: Positional power arises when a leader occupies a legitimate position of authority. The power is positional in that it reside s in the office held; leaders get this power through being appointed to fill the position (Bal et al. 7). The organization specifies the powers held by the individual in that position and how such an individual can direct the subordinates. The legitimacy of positional power arises from the formal nature of the position. Examples of positions that have power in the organization include managers and chief executive officers. Individuals in such positions hold different levels of power, increasing as people move up in the hierarchy (9). For instance, junior level managers may have the power to recommend a promotion or punishment, while the CEO may offer the last word on the matter. Like any other form of power, the