A group II metal hydroxide Essay Example for Free

A group II metal hydroxide Essay To find the identity of X(OH)2 (a group II metal hydroxide) by determining its solubility from a titration with 0.05 mol dm-3 HCL Theory:1. Titrations are the reaction between an acid solution with an alkali. In this reaction (called neutralization), the acid donates a proton (H+) to the alkali (base). When the two solutions are combined, the products made are salt and water. For example: 2HCl(aq) + X(OH)2 (aq) XCl2 (aq) + 2H2O (l) This shows the one of the products i. e. salt being XCl2 and water. So titration therefore helps to find the concentration for a solution of unknown concentration. This involves the controlled addition of a standard solution of known. Indicators are used to determine, at what stage has the solution reached the equivalence point'(inflextion point). This means at which, does the number of moles base added equals the number of moles of acid present. i.e. pH 7 Titration of a strong Acid with a Strong Base: As shown in the graph, the pH goes up slowly from the start of the tiration to near the equivalence point. i.e (the beginning of the graph). At the equivalence point moles of acid equal mole of base, and the solution contains only water and salt from the cation of the base and the anion of the acid. i.e. the vertical part of the curve in the graph. At that point, a tiny amount of alkali casuses a sudden, big change in pH. i.e. neutralised. Also shown in the graph are methyl orange and phenolpthalein. These two are both indicators that are often used for acid-base titrations. They each change colour at different pH ranges. For a strong acid to strong alkali titration, either one of those indicators can be used. However for a strong acid/weak alkali only methyl orange will be used due to pH changing rapidly across the range for methyl orange. That is from low to high pH i.e. red to yellow respectively pH (3.3 to 4.4), but not for phenolpthalein. Weak acid/strong alkali, phenolpthalein is used, the pH changes rapidly in an alkali range. From high to low pH, that is from pink to colourless pH(10-8.3) respectively but not for methyl orange. However for a weak acid/ weak alkali titrations theres no sharp pH change, so neither can work. Therefore in this investigation, the titration will be between a 0.05 mol dm-3 of HCl with X(OH)2, using phenolphthalein. Dependant Variable: Is the volume of HCl to achieve a colour change that is from pink to colourless. The Controlled variables : 1. the same source of HCl 2. same concentration of HCl 3. Same source of X(OH)2 4. Same volume of X(OH)2 5. Same equipment, method, room temperature Controlled Variables How to control How to monitor 1. Same source of HCl Using the same batch of HCl or from the same brand will control this. If the concentration was not to be same throughout, then this will cause different ratios of the components of the solution, that might cause different volume of HCl to be obtained for the neutralization to occur. 2. Same concentration of HCl This will be controlled by using the same batch of HCl and from the same source i.e. the same brand. By using the same batch ensures that the reactant concentration is the same. If another batch were to be used causes the concentration to differ. This causes the HCl obtained to be different. 3.Same source of X(OH)2 Using the same batch of X(OH)2 or from the same brand will control this. If the concentration was not to be same throughout, then this will cause different ratios of the components of the solution that might cause different volume of HCl to be obtained for the neutralization to occur. 4. Same volume of X(OH)2 This will be controlled by using the same batch of X(OH)2 and from the same source i.e. the same brand. By using the same batch ensures that the reactant concentration is the same. If another batch were to be used causes the concentration to differ. This causes the HCl obtained to be different. 5. Same equipment, method, room temperature The method would be kept the same and the same set of equipment and brand will need to be used throughout. The room temperature will be kept throughout at 180C by using a water bath. If different equipment or brands were used then there would be a lot of anomalies in the experiment causing a huge amount of inaccuracy of measurement particularly. Results: Raw data results were collected by using 25.00 cm3 of X(OH)2 with phenolphthalein and the volume of HCl was obtained by the solution going from pink to colourless. The volume of HCl found in 50.0cm3 burette à ¯Ã‚ ¿Ã‚ ½ 0.05 cm3 Trial 1 Trial 2 Trial 3 Trial 4 Average 19.600 19.800 19.600 19.700 19.675 Qualitative results that occurred during the experiment: * Conical flask swirling not even between the trials * Difficult to judge colourless solution change subjective end point * Ability to measure 25cm3 * Filling of burette accurately with HCl 0 point in right spot * Residual distilled water or solutions remain in conical flask i.e. diluted/interfered with subsequent solutions of X(OH)2 Average = trials (1+2+3+4)/4 Therefore: (19.6 + 19.8 + 19.6 + 19.7)/4 = 98.5/4 = 19.675 Due to the equation being 2HCl(aq) + X(OH)2 (aq) XCl2 (aq) + 2H2O (l) Therefore the ratio is 2:1 of 2 HCl : 1 X(OH)2 So using the equations mentioned above: Moles of acid is the number of moles= concentration X volume i.e. the volume will be used from the average Therefore: =0.05mol/dm3 x 19.675 cm3 =19.6 cm3 / 1000 = 0.0196 dm3 =0.05mol/dm3x0.0196 dm3 = 0.00098 moles So Moles of alkali in 25.000 cm3 Moles of HCl / 25.000 cm3 due to the ratio being 2:1, therefore 0.00098/2= 0.00049 moles of HCl So now the ratio is 1:1 so 0.00049 moles of X(OH)2 Moles of alkali in 100 cm3 It is assumed that there are four lots of 25 cm3 = 4 x 0.00049 = 0.00196 moles The next series of results will be used to calculate solubility of each compound by their mass in 100 cm3 The total Mr has been calculated in the table below for each compound. This was done by : Mr of X + ((O + H) X 2). Each element Mr for the following elements (OH)2 Total Mr Be 9.010 (16.00 +1.01) X 2 = 34.020 43.030 Mg 24.310 (16.00 +1.01) X 2 = 34.020 58.330 Ca 40.080 (16.00 +1.01) X 2 = 34.020 74.100 Sr 87.620 (16.00 +1.01) X 2 = 34.020 121.640 Ba 137.340 (16.00 +1.01) X 2 = 34.020 171.360 To obtain the solubilitys of metal II hydroxides is moles X Mr of the compound Therefore this table shows the calculation for the solubilitys for each of the different compounds Each element Total Mr Moles of X(OH)2 Solubiltity given as g/100 cm3 Literature values of the compounds given as g/100 cm3 Be(OH)2 43.03 0.00196 0.0843 0.000 Mg(OH)2 58.33 0.00196 0.114 0.001 Ca(OH)2 74.10 0.00196 0.0145 0.170 Sr(OH)2 121.64 0.00196 0.0238 0.770 Ba(OH)2 171.36 0.00196 0.335 3.700 Uncertainties: The uncertainty in measurement: Uncertainty due to pipette of 25.000 cm3 : Volume of X(OH)2 = à ¯Ã‚ ¿Ã‚ ½ 0.100 cm3 Percentage uncertainty = (0.1/25) X 100 = 0.400% Uncertainty due to Burrette of 50.000 cm3: Assumed due to measured volume of 19.675 cm3 and the uncertainty due to the smallest unit of measurement being 0.1 cm3 Therefore 0.1/2= à ¯Ã‚ ¿Ã‚ ½ 0.050 cm3 Percentage uncertainty = (0.05 /19.675) X 100 = 0.254% Therefore total uncertainty = 0.400% + 0.254% = 0.654% Conclusion and Evaluation: X(OH)2 is most likely to be Ca(OH)2 as the calculated solubility is closest to the literature value given of Ca(OH)2. The solubility for Ca(OH)2 0.145 g/100 cm3 and the literature value is 0.170 g/100 cm3. This shows that the difference is only 0.025 cm3. However the comparison between Be(OH)2 of the calculated solubility is 0.0843 g/100 cm3 and of its literature value 0.000 g/100 cm3 . Shows that there is a greater difference. Showing that it cannot be X(OH)2 solution. This is also shown for Mg(OH)2 as the difference between the calculated solubility and the literature value is 0.113 g/100 cm3, showing that it still has a greater difference than Calcium hydroxide does. The difference between Sr(OH)2 and its literature value is 0.532g/100 cm3. However the difference between the calculated solubility of Barium hydroxide and the literature value is 3.365 g/100 cm3 showing there is a great difference so it cannot be Barium hydroxide. The percentage error of Ca(OH)2 = [(0.170 0.145)/0.170] X 100 = (0.025/0.170) X 100 = 14.705% Throughout the experiment there were systematic errors and random errors that were met. Uncertainties/limitations Error Type of error Quantity of error Explanation for error Improvements Measurement in burette Systematic error +/- 0.05cm3 Equipment limitation, this is because the line where each of the reading might not be precise. Different manufacturer should be used with multiple trials in order to increase the accuracy of the calculated value to the literature value. Measurement in pipette Systematic error +/-0.1cm3 Equipment limitation, this is because due to the pipette only holding 25 cm3 of volume. The line could have been where the actual reading might not be Causing the result to not be precise. Different manufacturer should be used with multiple trials in order to increase the accuracy of the calculated value to the literature value. Point of colour change Random error Not quantifiable Human observation subjective measurement. This is because even though a white tile is used, it is unclear as to what point has the solution gone colourless. Use alternative indicator for several different trials, use pH meter to assess neutralization point. Therefore there will be a more precise point as to when the solution becomes green. Temperature fluctuations Random error Not quantifiable There can be a change of measurements of equipment due to variation in expansion and contraction of materials. Due to the temperatures not being constant from the fan, windows or from the air conditioner. Controlled lab environment of the temperature by using a water bath at 180C with no air conditioner, fans working. To ensure no fluctuations occur. Fluctuations in humidity of room Random error Not quantifiable Change solution concentrations due to differences in evaporation rate in the surrounding air. Controlled lab environment Calibration error in burette Systematic error Not quantifiable 0 line incorrectly marked Divisions on burette inaccurate Use different manufacturers equipment for other trials Calibration error in pipette Systematic error Not quantifiable 25cm3 line incorrectly marked. Because it is unclear as to where the true meniscus lies. Causing the values measured out to be not precise. Also due to there being only one line causes a further decrease in the precision of the results. Use different manufacturers equipment for other trials to ensure that the accuracy increases. Another improvement that will be done, if the experiment were to be repeated is that due to the inaccuracy of the conical flask being swirled. If the conical flask is being swirled unevenly there is a chance of inaccurate results of when the colourless solution occurs. Therefore a stirring rod should be used to increase the accuracy of the swirls of the reaction in the conical flask. Another limitation that arouse in this experiment that would be improved if the experiment were to be done again is that after the neutralization reaction had occurred, there would still be some residue of the distilled water used to rinse out the equipment. This can be improved by increase the number of repeats of rinse. This would ensure that more of the diluted solution would have been removed. Also the trials can also increase, to 10 repeats so that there is more variance so that the accuracy increases. Another improvement might be, to use different indicator, for example methyl orange. Due to the colour change would be from red to yellow would make it easier for the pH 7 to be more easily recognized against a white tile then it was with phenolphthalein. Cited Sources: 1. http://www.vigoschools.org/~mmc3/c1%20lecture/Chemistry%201-2/Lecture%20Notes/Unit%205%20-%20Acids%20and%20Titration/L3%20-%20Acid-Base%20Reactions%20and%20Titration.pdf

Essay --

In 1815 The Battle of New Orleans was fought, became the largest battle of the war of 1812, and was won by Andrew Jackson. From that time he was recognized as a national hero for winning such a huge war, even though the Treaty of Ghent was the armistice which had ended the War of 1812, and was signed earlier than when The Battle of New Orleans occurred. The Product of The War of 1812 was nationalism. â€Å"America may not have fought the war as one nation, but it emerged as one nation.† (â€Å"Nascent Nationalism†). American art and literature had developed and proceeded to show that nationalism began. â€Å"Washington Irving and James Fenimore Cooper attained international recognition in the 1820s, significantly as the nation’s first writers of importance to use American scenes and themes† (â€Å"Nascent Nationalism†). American authors had begun to receive equal attention to European writers, and were capable of achieving the level of writing only European authors were recognized as having. â€Å"Irving’s Bracebridge Hall (1822) received at least 32 reviews in the British press, equaling the attention given the work of the two most popular British authors, Byron and Scott.† (Eaton). The American System, similar to the Federalist System, produced economic diversification and represents an effect of nationalism, with its goal to create a unified expanding economy. Henry Clay wanted to create a strong national bank, which would grant lots of mortgages in the West and South. He also envisioned a strong transportation system. The tariff of 1816 was the first tariff in American history passed by Congress â€Å"instituted primarily for protection and revenue† (â€Å"The American System†). Clay wanted a protective tariff that would allow for the flourishing of eastern ma... ... A strong central government was important to Jackson. This strengthened the improved and developed American nationalism. With the belief in a strong democracy and increased involvement and power of man in the government, Jackson supported the rise of nationalism. Nationalism pushed Jackson to make decisions, which shaped the country. This was shown when he threatened South Carolina by getting military ready for action to enforce the federal tariff. Although South Carolina did not go along with paying the tariff, they complied with the government and their idea of collecting a federal tariff. Nationalism imposed many different ideas and was the guiding factor in important American leader’s decisions. Nationalism, as a political ideology shaped the social life of Americans, and was responsible for the political culture of the United States within the years 1815-1836.

Internal Control Essay

1. Inform the president of any new internal control requirements if the company decides to go public Each of the five components of an internal control system is important. Let us focus on the control activities. These activities are the backbone of the company’s efforts to address the risks it faces, such as fraud. The specific control activities used by a company will vary depending on management’s assessments of the risks faced. The six principles of control activities are as follows: a. Establishment of responsibility b. Segregation of duties c. Documentation procedures d. Physical controls e. Independent internal verification f. Human resource controls All these apply to most companies and are relevant to both manual and computerized accounting systems. Establishment of responsibility: An essential principle of internal control is to assign responsibility to specific employees. Control is most effective when only one person is responsible for given task. Establishing responsibility often requires limiting access only to authorized personnel and then identifying those personal. Segregation of duties: Segregation of duties is indispensable in an internal control system. There are two common applications of this principle: a. Different individuals should be responsible for related activities. b. The responsibility for record-keeping for an asset should be separate from the physical custody of that asset. The rationale for segregation of duties is, the work of one employee should, without a duplication of effort, provide a reliable basis for evaluating the work of another employee. Segregation of related activities – Making one individual responsible for related activities increases the potential for errors and irregularities. Segregation of record-keeping from physical custody – The custodian of the asset is not likely to convert the asset to personal use when one employee maintains the record of the asset, and a different employee has physical custody of the asset. Documentation procedures: Documents provide evidence that transactions and events have occurred. By requiring signatures on the documents, the company can identify the individual responsible for the transaction or event. Companies should document transactions when the transaction occurs. Companies should establish procedures for documents. First, whenever possible, companies should use pre numbered documents, and all documents should be accounted for. Pre numbering helps to prevent a transaction from being recorded more than once or conversely from not being recorded at all. Second, the control system should require that employees promptly forward source documents for accounting entries to the accounting department. This control measure helps to ensure timely recording of the transaction and contributes directly to the accuracy and reliability of the accounting records. Physical controls: Use of physical controls is essential. Physical controls relate to the safeguarding of assets and enhance the accuracy and reliability of the accounting records. Independent internal verification: Most internal control systems provide for independent internal verification. This principle involves the review of data prepared by employees. To obtain maximum benefit from independent internal verification: a. Companies should verify records periodically or on a surprise basis b. An employee who is independent of the personnel responsible for the information should make the verification c. Discrepancies and exceptions should be reported to a management level that can take appropriate corrective action. Independent internal verification is especially useful in comparing recorded transactions with existing assets. Large companies often assign independent internal verification to internal auditors. Internal auditors are company employees who continuously evaluate the effectiveness of the company’s internal control systems. They review the activities of departments and individuals to determine whether prescribed internal controls are being followed. They also recommend improvements when needed. Human resource controls: Human resource control activities include the following: a. Bond employees who handle cash – Bonding involves obtaining insurance protection against theft by employees. It contributes to the safeguarding of cash in two ways: First, the insurance company carefully screens all individuals before adding them to the policy and may reject risky applicants. Second, bonded employees know that the insurance company will vigorously prosecute all offenders. b. Rotate employees’ duties and require employees to take vacations – these measures deter employees from attempting thefts since they will not be able to permanently conceal their improper actions. c. Conduct through background checks – Many believe that the most important and inexpensive measure any business can take to reduce employee theft and fraud is for the human resources department to conduct through background checks. 2. Advice the president of what the company is doing right (they are doing some things well) and also recommends to the President whether or not they should buy the indelible ink machine. When you advise the President, please be sure to reference the applicable internal control principle that applies. Some of the things that the company is doing right are: a. Documentation procedures – The organization uses pre numbered invoices. Documents provide evidence that transactions and events have occurred. This internal control activity says that whenever possible the companies should use pre numbered documents and all documents should be accounted for. Pre numbering helps to prevent a transaction from being recorded more than once or conversely from not being recorded at all. This control measure helps to ensure timely recording of the transaction and contributes directly to the accuracy and reliability of the accounting records. b. Establishment of responsibility – The organization uses petty cash. Employees are asked to place a note if they use any of the cash. This is according to the internal control activity ‘Establishment of responsibility’. This is an essential principle of internal control is to assign responsibility to specific employees. Control is most effective when only one person is responsible for a given task. This limits access only to authorized personnel. c. While interviewing, the president and the accountant do it together. It is good to have more than one people in an interview. d. The fact that he realizes the issues of any problems The president should not buy the indelible ink machine, because anyone in the company will have the access to print. The president has to voluntaries himself and decides about the indelible ink machine. He need not wait for authorization from anybody on installing this indelible ink machine. 3. Advice the president of what the company is doing wrong (they are definitely doing some things poorly). Please be sure to include the internal control principle that is being violated along with a recommendation for improvement. Some of the things that the company is doing wrong are: a. Meeting in a public place to discuss. This should happen in a private room. b. Physical control – The Company does not follow the physical control activity. The company does not have individual passwords to restrict access. The use of physical controls is essential. Physical controls relate to the safeguarding of assets and enhance the accuracy and reliability of the accounting records. The organization should have individual passwords for all employees. c. Establishment of responsibility – The Company does not follow the internal control activity of establishing responsibility. The indelible ink machine is a wrong option because anyone can use the machine to print. An essential principle of internal control is to assign responsibility to specific employees. Control is most effective when only one person is responsible for a given task. d. Human resource controls – The organization does not follow the human resource controls internal activity. Among the human resource controls internal activity, they do not follow the conduct thorough background checks. The company did not do background check. The employee did pornography and was a convicted felon who served time for molesting children. Conducting thorough background checks is the most important and inexpensive measure any business can take to reduce employee theft and fraud for the human resources department. The two tips are: 1. Check to see whether job applicants actually graduated from the schools they list. 2. Never use the telephone numbers for previous employees given on the reference sheet; always look them up yourself. The company must conduct background checks when recruiting. e. They have faith in their long term employees. The long term employees know well about the organization f. Establishment of responsibility – The organization does not have a responsible person for issuing the pay checks. This is an essential principle of internal control to assign responsibility to specific employees. Control is most effective when only one person is responsible for a given task. The company leaves the payday checks in the office for pick up. The paychecks should be mailed separately or it should be deposited directly into the employees’ account. Else one person should have the responsibility to handle the paycheck on pay day. g. Segregation of duties – It is an indispensable internal control system that the organization is not following. The two common applications of this principle are: Different individuals should be responsible for related activities and the responsibility for record keeping for an asset should be separate from the physical custody of that asset. Making one individual responsible for related activities increases the potential for errors and irregularities. The custodian of the asset is not likely to convert the asset to personal use when one employee maintains the record of the asset and a different employee has physical custody of the asset. In a company, same person cannot be both the treasurer and controller. The duties of the employees must be segregated clearly. h. Physical control – Use of physical controls is essential. Physical controls relate to the safeguarding of assets and enhance the accuracy and reliability of the accounting records. There is no internet sec urity in the company. They should have proper internet security.

The Construction And Development Of Self Identity By...

Article Evaluation The research focus/ Gap/ Intended audience The study aims to investigate the construction and development of self-identity by foreign national students (FNSs) who decided to teach in a British public school after completing a Post Graduate Certificate of Education (PGCE) Course. The goal of the study is to shed light on how these FNSs, who are mostly from French, Germany or Spain, project their national identity or sometimes distance themselves from their homeland. This study was motivated by the lack of studies that explore FNSs social and cultural background, their national identities, and their unique educational system. The main audience for this article are people who involved in education policy making in the U.K,†¦show more content†¦The summary is well-written and informative, including the purpose of the study, who the participants are, the methods, and the results. However, the summary lacks the general implications of the study, such as why participants either align or distance themselves from national ide ntity. The result section includes a thick description of how FNSs project their identities by either referring to their home country or detach themselves completely from their national identities. In the conclusion, the author does not give any suggestions or directions for future research. Key Theories/ Literature The key theories and concepts that frames this study are self-identity, especially national identity, multiple subjectivities, and racial stereotyping theories. The study draws upon all of the mentioned key theories and concept. Research Questions/Hypotheses Since it is a qualitative research, the hypotheses were not proposed and tested before gathering data and listening to what the participants say about their experiences. The research questions or hypotheses were not explicitly expressed for this study. However, the author anticipated some problems, such as feeling like outsiders at work, always feeling the need to defend their national identity, and having to handle the differences between the U.K. educational system and their