Determination of the pKas for Glycine

Determination of the pKas for Glycine Name: Aleksandra Redlinska Lab Partner: Adrianna Czerlonko Lab Instructor: Jenq-Kuen Huang Lab TA: Chandra K.Ailneni Objectives: The purpose of this experiment is to titrate glycine and determine its pKa values. This is done to show that glycine is a dipolar ion. This experiment will help explain how pKa values and pH are closely related and will help show the importance of pH in amino acids. Background: Amino acids consist of an amino group (-NH3+) and a carboxyl group (-COOH). When they are in an acidic solution, the amino group becomes protonated and the carboxyl group gets dissociated. When in a solution with a neutral pH, amino acids will usually be dipolar and the amino group will be protonated while the carboxyl group becomes deprotonated. When amino acids are in basic solution, the protonated amino group is the only one that changes, by losing a proton (Biochemistry). The equation used to find the equilibrium constant, Ka, of a reaction is the products divided by the reactants. The Ka can then be used to find the pKa by taking the negative log of the Ka. The Ka value can be used to figure out whether the acid will dissociate or not and how strong an acid is. Glycine is an amino acid which contains both acidic and basic pKas. This shows that it can react to changes in the pH. By adding NaOH to glycine, the proton ion will dissociate. This dissociation will occur due to the tit ration done using the glycine solution. Materials: 0.1 N Sodium hydroxide (60 mL) Glycine (0.6 g or 8.0 meq) 0.1 N Hydrochloric acid (60 mL) Deionized water 100 mL volumetric flask Two burettes Four 250 mL beakers Funnel Graduated cylinder pH meter Procedure: Glycine (0.6 g) was weighed out and put in a 100 ml flask. Water was added to the flask to make 100 mL of solution. The sample (25 mL) was transferred to a 250 mL beaker and distilled water was added (100 mL). The solution was titrated with 0.1 N NaOH (30 mL in 1.0 mL increments). The pH and volume of base were measured after each 1.0 mL of NaOH added and the data was recorded and plotted. Distilled water (125 mL) was placed in a 250 mL beaker. The solution was once again titrated with 0.1 N NaOH (30 mL in 1.0 mL increments). The pH and volume of base were once again collected and plotted. The original glycine solution (25 mL) was transferred to a 250 mL beaker and distilled water (100 mL) was added. The solution was titrated with 0.1 N HCl (30 mL in 1.0 mL increments). The total volume of acid and the pH were recorded. Distilled water (125 mL) was placed in a 250 mL beaker and the solution was titrated with 0.1 N HCl (30 mL in 1.0 mL increments). The volume of the acid and the pH wa s recorded and plotted. Results: Table 1. Titration with NaOH. Table 2. Titration with HCl. Calculations: Determining pKa1 (HCl titration) At pH = 2.5, 30 mL of 0.1 N HCl was used for the glycine titration and 16 mL was used for water. 30 mL – 16 mL = 14 mL 14 mL = 0.014 L 0.014 L was used to titrate glycine at pH 2.5 The normality of HCl used was 0.1 N N = #eq/L 0.1 N = X/0.014 L X = 0.0014 eq 0.0014 eq = 1.4 meq It takes 1.4 meq of HCl to convert glycine to an acidic form The amount of glycine at the start of the titration was: (8 meq)(25 mL/100 mL) = 2 meq The amount of glycine left after the titration was: 2 meq – 1.4 meq = 0.6 meq Formula: pH = pKa1 + log [conjugate base]/ [acid] Conjugate base = 0.6 meq Acid = 1.4 meq 2.5 = pKa1 + log [0.6]/[1.4] 2.5 = pKa1 – 0.368 pKa1 = 2.868 Determining pKa2 (NaOH titration) At pH = 9.4, 18 mL of 0.1 N NaOH was used for the glycine titration and 1 mL was used for the water. 18 mL – 1 mL = 17 mL 17 mL = 0.017 L 0.017 L was used to titrate glycine at pH 9.4 The normality of HCl used was 0.1 N N = #eq/L 0.1 N = X/0.017 L X = 0.0017 eq 0.0017 eq = 1.7 meq It takes 1.7 meq of NaOH to convert glycine to an acidic form The amount of glycine at the start of the titration was: (8 meq)(25 mL/100 mL) = 2 meq The amount of glycine left after the titration was: 2 meq – 1.7 meq = 0.3 meq Formula: pH = pKa2 + log [conjugate base]/ [acid] Conjugate base = 1.7 meq Acid = 0.3 meq 9.4 = pKa2 + log [1.7]/[0.3] 9.4 = pKa2 + 0.753 pKa2 = 8.647 Discussion and Conclusion: The average pKa1 calculated for the titration using HCl was 3.013. The true pKa 1 for an acidic amino acid is 2.3. The average pKa2 calculated for the titration using NaOH was 8.863. The true pKa2 for a basic amino acid is 9.6. This difference could have been caused by dirty glassware or improper measuring of the 0.1 increments of HCl and NaOH using the burette. The error could have also been due to the absence of an analytical scale to make precise measurements of glycine and the pH meter not being cleaned thoroughly enough. Since there was not enough time for each group to complete both parts of the experiment using HCl and NaOH, each group only did one of the titrations. Since my group did not have time to do the HCl titration, we got the results from another group. This could have also caused an error because we did not monitor how precise the other group was. This experiment shows that the pKas of amino acids are important. They could be used to calculate the pH and strength of the amino acid. This observation is displayed in the data above and the graph. This experiment helped me understand how pKa and pH are related. References: Berg, Jeremy M., John L. Tymoczko, and Lubert Stryer.Biochemistry. 6th Edition, W.H. Freeman and Company, New York, (2002). Cronk, J. (2012, January 1). BIOCHEMISTRY Dictionary. Retrieved September 23, 2014, from http://guweb2.gonzaga.edu/faculty/cronk/biochem/dictionary.cfm?letter=front Cronk, J. (2012, January 1). CHEM 440 lectures. Retrieved September 23, 2014, from http://guweb2.gonzaga.edu/faculty/cronk/CHEM440pub/L05-index.cfm Huang, Jack. Experiment 2: â€Å"Determination of the pKas for Glycine† Chem 421 Laboratory. Sep 15, 2014. Answers to Questions: 1. The pKa associated with a typical aliphatic carboxylic acid is 2.3 and the pKa associated with a typical aliphatic amine is 9.6. The pKas associated with an alpha-carboxyl group in an amino acid are between 2 and 3. The pKas associated with a gamma-carboxyl group in an amino acid are between 4.3 and 4.5. The pKas associated with an alpha-amino group in an amino acid are between 9 and 10. The pKa associated with an epsilon-amino group in an amino acid is around 10. The pKas associated with an imidazole group in an amino acid are between 6 and 7. The pKas associated with a guanidine group in an amino acid is around 12.5. The pKas for these groups are taken away once the amino acids are incorporated into proteins. The groups form bonds and the only pKa values that can still be seen are the ones that are at the C and N terminus of the chain. 2. The top equation is correct because the top equation contains a Zwitterion. This Zwitterion would cause it to be able to react with HCl (a strong base) and NaOH (a strong acid). The bottom equation shows no charges on the nitrogen or oxygen, making the reaction not able to happen. My data supports this because when adding HCl, the pH went down and when adding NaOH, the pH went up. This shows that ions were taken away and added causing deprotonation and protonation of the glycine. 3. The structure of Lys-Ala-Asp is: The N-terminal is the NH3+ on the very left side and the C-terminal is the OH on the right side. The net charge of this tripeptide at pH 2 is +2. The net charge at pH 6 is 0. The net charge at pH 13 is -2.

Anosognosia for Hemiplegia: A Window into Self-Awareness :: Stoke Medical Essays

Anosognosia for Hemiplegia: A Window into Self-Awareness You wake up in a hospital bed, scared, confused, and attached to a network of tubes and beeping equipment. After doctors assault you with a barrage of questions and tests, your family emerges from the sea of unfamiliar faces surrounding you and explains what has happened; you have had a stroke in the right half of your brain, and you are at least temporarily paralyzed on your left side. You wiggle your left toes to test yourself; everything seems normal. You lift your left arm to show your family that you are obviously not paralyzed. However, this demonstration does not elicit the happy response you expect; it only causes your children to exchange worried glances with the doctors. No matter how many times you attempt to demonstrate movement in the left half of your body, the roomful of people insists that you are paralyzed. And you are, you just do not know it. How is this possible? You are suffering from anosognosia, a condition in which an ill patient is unaware of her own ill ness or the deficits resulting from her illness (1). Anosognosia occurs at least temporarily in over 50% of stroke victims who suffer from paralysis on the side of the body opposite the stroke, a condition known as hemiplegia (1). Patients with anosognosia for hemiplegia insist they can do things like lift both legs, touch their doctor's nose with a finger on their paralyzed side, and walk normally (2). These patients are much less likely to regain independence after their stroke than patients without anosognosia, primarily because they overestimate their own abilities in unsafe situations (3). However, the implications of the illness go far beyond those for patients who suffer from it; anosognosia brings questions of the origin of self-awareness to the forefront. How can someone lose the ability to know when she is or is not moving? Is this some type of elaborate Freudian defense mechanism, or is this person entirely unaware of her illness? How is self-awareness represented in the brain, and is this representation isolated from o r attached to awareness of others? Though none of these questions are fully answerable at this time, research into anosognosia has provided scientists and philosophers with insight into some of these ancient questions of human consciousness. The question of "denial" versus "unawareness" is at the heart of debate between psychologists and neurologists about the origin of anosognosia (3). Anosognosia for Hemiplegia: A Window into Self-Awareness :: Stoke Medical Essays Anosognosia for Hemiplegia: A Window into Self-Awareness You wake up in a hospital bed, scared, confused, and attached to a network of tubes and beeping equipment. After doctors assault you with a barrage of questions and tests, your family emerges from the sea of unfamiliar faces surrounding you and explains what has happened; you have had a stroke in the right half of your brain, and you are at least temporarily paralyzed on your left side. You wiggle your left toes to test yourself; everything seems normal. You lift your left arm to show your family that you are obviously not paralyzed. However, this demonstration does not elicit the happy response you expect; it only causes your children to exchange worried glances with the doctors. No matter how many times you attempt to demonstrate movement in the left half of your body, the roomful of people insists that you are paralyzed. And you are, you just do not know it. How is this possible? You are suffering from anosognosia, a condition in which an ill patient is unaware of her own ill ness or the deficits resulting from her illness (1). Anosognosia occurs at least temporarily in over 50% of stroke victims who suffer from paralysis on the side of the body opposite the stroke, a condition known as hemiplegia (1). Patients with anosognosia for hemiplegia insist they can do things like lift both legs, touch their doctor's nose with a finger on their paralyzed side, and walk normally (2). These patients are much less likely to regain independence after their stroke than patients without anosognosia, primarily because they overestimate their own abilities in unsafe situations (3). However, the implications of the illness go far beyond those for patients who suffer from it; anosognosia brings questions of the origin of self-awareness to the forefront. How can someone lose the ability to know when she is or is not moving? Is this some type of elaborate Freudian defense mechanism, or is this person entirely unaware of her illness? How is self-awareness represented in the brain, and is this representation isolated from o r attached to awareness of others? Though none of these questions are fully answerable at this time, research into anosognosia has provided scientists and philosophers with insight into some of these ancient questions of human consciousness. The question of "denial" versus "unawareness" is at the heart of debate between psychologists and neurologists about the origin of anosognosia (3).

Tampakan Mining – Case Study

Tampakan Project Sustainability Report 2010 Contents 1 1 2 4 6 10 12 16 20 22 About the Tampakan Copper Gold Project Map of operations Executive General Manager’s message General Manager’s message Targets and Scorecard Scope of the report Our sustainable development strategy and corporate governance Corporate governance and Sustainable Development management system Our economic contributions Case study: Training in high-value crop production boosts income, prepares farmers for Tampakan Project 24Our people and their workplace 24 Employing locally 24 Employee training and education 25 Labor relations 25 Non-discrimination policy 28 29 29 29 29 29 29 29 29 30 31 Safety and Health behavioral based Safety (bbS) Safest mine award Occupational health Health control and services Health and hygiene monitoring First Aid and emergency response Health promotion and awareness Health impact assessment Case study: Hazard reporting Case study: Tampakan Project promotes safety culture inside and out 32 32 32 33 33 33 33 34 34 34 35: 36 37Sustainable communities Corporate Social Involvement Socio-economic sustainability Environment programs Cultural sustainability Stakeholder consultation and engagement Community sustainability management systems Community grievance Free and Prior Informed Consent and resettlement Artisanal and small-scale mining Case study: mobile Community Information and Resource Center Case study: SMI supports innovative education programs Case study: SMI trains barangay health workers 38 38 38 39 39 39 39 40 40 40 40 40 41 42 43 43 43 45 46 47Environmental performance Environmental incidents Reforestation program Environmental Management System Environmental Impact Assessment Water management biodiversity Climate change Waste management Energy Mine closure and rehabilitation Ongoing rehabilitation post mine closure Case study: Training on production of high-quality seedlings Case study: Study on Lake buluan completed Product stewardship Coppe r and Sustainable Development Copper and health Summary of key sustainability data Global Reporting Initiative Index Glossary About Xstrata plcXstrata is a global diversified mining group, listed on the London and Swiss stock exchanges. Headquartered in Zug, Switzerland, Xstrata maintains a meaningful position in seven major international commodity markets: copper, coking coal, thermal coal, ferrochrome, nickel, vanadium and zinc, with additional exposure to gold, cobalt, lead and silver. The Xstrata Group also comprises a growing platinum group metals business, iron ore projects, recycling facilities and a suite of global technology products, many of which are industry leaders. The Group’s operations and projects span 20 countries.About Xstrata Copper Xstrata Copper is the world’s fourth largest copper producer. In 2010, its attributable mined production of copper contained in cathodes and concentrates reached 931,500 tonnes. It is also one of the world’s large st producers of smelter and refined copper, including from third-party materials. Headquartered in brisbane, Australia, Xstrata Copper is one of the commodity business units within the major global diversified mining group, Xstrata plc. Its mining and metallurgical operations and development projects span eight countries: Argentina, Australia, Canada, Chile, PapuaNueva Guinea, Peru, the Philippines and the United States. Its operations and projects are administered through a regional divisional management structure, which ensures that critical decisions are taken close to the related businesses. Xstrata Copper also has a recycling business (Xstrata Recycling) with plants in the United States and offices in Canada and Asia. b TAMPAKAN PROJECT About the Tampakan Copper-Gold Project The Tampakan Copper-Gold Project is located on the southern Philippine island of Mindanao, approximately 40 kilometers north of General Santos City.The Project is situated on the boundaries of four province s: South Cotabato, Sarangani, Sultan Kudarat and Davao del Sur, and represents one of the world’s largest undeveloped copper-gold deposits. The Tampakan Project is a 2. 4 billion metric ton deposit, containing 13. 5 million metric tons of copper and 15. 8 million ounces of gold at a 0. 3 % cut-off grade. The Project is operated by Philippine-based affiliate Sagittarius Mines, Inc. (SMI), whose 40% controlling equity is a joint venture between Xstrata Copper (62. 5%) and Indophil Resources NL (37. %). The 60% non-controlling equity shareholders of SMI are the Tampakan Mining Corporation and Southcot Mining Corporation (known as the Tampakan Group of Companies). SMI submitted the Mining Project Feasibility Study for the Tampakan Project to the Philippine government in April 2010 and is progressing with the Mine and Off-site Environmental Impact Assessments (EIAs). SMI expects to submit the Mine Environmental Impact Statement (EIS) to the government by the second half of 2011. I n December 2010, the Project employed 372 employees and 1,185 contractors.The Tampakan Project is managed by Xstrata Copper and adheres to the Xstrata Group’s industry-leading Sustainable Development (SD) Policy and Standards, business Principles, Code of Conduct and Policy on bribery, Fraud and Corruption. Map of operations Manila Catanduanes Mindoro Masbate Samar Ley te Cebu Negros Palawan MINDANAO Zamboanga Davao Tampakan General Santos SUSTAINAbILIT y REPORT 2010 1 Executive General Manager’s message Xstrata Copper’s Asia Pacific projects made significant progress in 2010, achieving a number of important milestones.The strong recovery in global demand for copper in 2010, together with robust copper prices, enabled Xstrata Copper to finish the year with a solid set of operational and financial results. The business was well positioned to take advantage of these favorable economic conditions as a result of the actions taken by our management teams during 2009 in response to the global financial crisis, including prudent cost reductions in the context of an unwavering focus on sustainable development and on our growth strategy.Xstrata Copper’s commitment to sustainable development remained firm in 2010 and was reflected in the 22 national and regional awards presented to our sites during the year for excellence in this field. At the Group level, Xstrata retained its position as Mining Sector Leader on the Dow Jones Sustainability Index in 2010/11, for the fourth consecutive year, and was named as the Super Sector Leader for basic Resources industries. As part of the Xstrata Group, the principles of sustainable development are integral to our business model and guide our daily decision-making.We take a systematic approach to setting targets, monitoring performance and reporting, both internally and externally, against our sustainable development policy, standards and targets. Throughout the year, our sustainable development performa nce was closely monitored and evaluated by the Xstrata Copper Sustainable Development Committee. Our sites also participated in a range of internal and external audits to provide assurance against the sustainability standards of Xstrata Copper and those of the Xstrata Group.Following an annual review of our management policies, we launched an integrated Xstrata Copper Sustainable Development Policy in May which: strengthened our published position on human rights; improved the alignment between the policy objectives of the Xstrata Group, Xstrata Copper and our operations; and simplified our overall sustainable development framework. Due to the significant advancement of our project development pipeline, in early 2010 Xstrata Copper restructured the organization of our project development activities to capitalize on our regional synergies in South America and Asia Pacific.Under the new structure, Executive General Manager – Project Development South America, bob Drabik, assume d responsibility for the development our Antapaccay, Las bambas and El Pachon projects in Peru and Argentina. As Executive General Manager- Project Development Asia Pacific, I retained responsibility for the Tampakan project in the Philippines and Frieda River project in Papua New Guinea. Our Asia Pacific projects made significant progress in 2010, achieving a number of important milestones. In April, the Tampakan project submitted its Mining Project Feasibility Study to the Philippine government.The project also completed its mine site Environmental Impact Assessment (EIA) in December, for public consultation and submission during 2011. In addition, the project commenced the EIA process for its offsite infrastructure, including the port, power station, filter plant, transmission lines and pipelines, in the second half of the year. The Frieda River project delivered its pre-feasibility study in October 2010 and commenced a drilling program and technical studies for a feasibility stu dy which is TAMPAKAN PROJECT scheduled for completion in January 2012. The project also continued to undertake extensive environmental baseline studies and stakeholder engagement activities for its ESIA which is scheduled for completion in 2011. The health and well-being of our employees, contractors and visitors continued to be a key priority for the Asia Pacific projects throughout the year. In 2010, the projects achieved their Lost Time Injury Frequency Rate (LTIFR) target of

Being A Non Traditional Student - 1945 Words

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This data is necessary to perform to function of the profession, but the expectation and trust is that it will not be disclosed without individual consent. While each profession has data access concerns, with major ethical implications, the majority of this data can be guarded and monitored by technological means and enforced with legal policy. As an information technologist it is often within your purview to employ these protections, and also to monitor that these safeguards are effective, and not being violated. There are two avenues that I believe can be approached when it comes to ethics in IT: unauthorized disclosure, andShow MoreRelatedBeing A Non Traditional Student1946 Words   |  8 PagesBeing a non-traditional student, I have the opportunity to attend school while also pursuing a career in Information Technology (IT). 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