Chemistry 366 Determination of Metal Ions in Crude Oils

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to answer some Qs on excel and word documents with good quality

the first Q on excel sheet, the rest of Qs on word document

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Chemistry 366 Mid-Term Exam, February 24, 2019 Dr. Van Bramer NAME___________________________ I have neither given nor received any unauthorized assistance on this exam. I have cited all references. Signature_______________________________ INSTRUCTIONS: For this exam you may use your textbook. You may not consult with other students or faculty. If you have any questions, consult Dr. Van Bramer. This exam contains several broad questions. Your grade depends upon clearly presenting a through answer to the question. Spend time organizing your answer. Wherever possible, answer questions in your own words. Use quotes sparingly to show a very specific thought. Strive to effectively communicate that you understand the answer to each question. Your ability to find and copy select passages from a wide range of sources will not impress me. Use your words and show me what you understand. You must cite pages and figures in your textbook or other resources that you use to answer questions. Failure to reference or using unauthorized sources (other students or faculty) will result in failure in the class. Submit a copy of your spreadsheet and your word document to the assignment on Canvas. Any spreadsheet must be well documented, so it is easy for me to find your answer and check your calculations. Any handwritten or hand drawn figures may be turned in directly to me or submitted electronically to canvas.. 1. (35 pts) A soil sample is analyzed for magnesium using atomic absorption spectroscopy. Your specific data for this question will be e-mailed directly to you. The experiment was done by: • Solution A. Replicate samples are weighted and combined with 20 mL of 16 M nitric acid and heated on a hot plate for 30 minutes in a 100 mL beaker. These beakers are labeled B1, B2, B3, etc. • 20 mL of deionized water was added to each beaker. The contents were filtered and rinsed, placed in a class A volumetric flask, and diluted to the mark with deionized water. The flasks were labeled F1, F2, F3, etc. The volume of the flask is listed in the spreadsheet sent to you. • A set of standards were prepared using class A transfer pipets and class A volumetric flasks. Details of the standards are in the spreadsheet sent to you. • All samples and standards were measured using a graphite furnace atomic absorption spectrometer with standard settings for magnesium. Using this dataset answer the following questions 1. (5 pts) Create a calibration curve, provide a properly labeled graph and report the slope and intercept. 2. (5 pts) Use the calibration curve to determine the concentration of magnesium in each of the sample solutions analyzed. 3. (5 pts) Use the data provided to determine the concentration of magnesium in each of the replicate soil samples. 4. (5 pts) Determine the average concentration of magnesium in the soil sample 5. (5 pts) Determine the 90% confidence interval for the concentration of magnesium in the soil sample based upon the replicate analysis. 6. (5 pts) If you found that these experimental results were significantly less than the accepted concentration of magnesium in this soil, what would be a possible explanation for this result. Please explain your reasoning. 7. (5 pts) If you found that these experimental results were significantly more than the accepted concentration of magnesium in this soil, what would be a possible explanation for this result. Please explain your reasoning. 2. (20 pts) Based upon your results in question 1. a. (10 pts) Briefly discuss the feasibility of doing this analysis using a flame atomic absorption spectrometer. In your answer demonstrate that you understand the advantages and disadvantages of flame and graphite furnace AA. b. (10 pts) Briefly discuss the feasibility of doing this analysis using an ICP atomic emission spectrometer. In your answer demonstrate that you understand the advantages and disadvantages of ICP atomic emission and graphite furnace AA. 3. (20 pts) Your manager has asked for recommendations on how to analyze petroleum samples for cadmium, chromium, lead, nickel, vanadium and zinc. Your job is to identify what instrumentation is best suited to this analysis. Prepare a brief memo that identifies your choice. Why this instrument is suited to this analysis. And why other instruments we have discussed this semester are not well suited to this analysis. 4. (10 pts) You are working for a forensics laboratory and you are analyzing a sample that is suspected of being a dilute cocaine solution. Cocaine has the formula C17H21NO4 and the structure is shown below: The mass spectrum of cocaine is available from the NIST Webbook is shown below, identify the molecular ion and explain how the molecular ion fragments to give the peak at m/z 182. 5. (15 pts) Use the figure below, identify the major components (items 2, 4, 5, 6, 8 in the figure) and describe how a monochrometer works. Figure from: Ocean Optics https://oceanoptics.com/product-details/usb4000-optical-bench-options/#5 Stock Standard (ppb) Standard Sample Data Volume Volumetric Flask (mL) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Trial 6 1000 V pipet (ml) V flask (ml) 0 50 1 100 2 100 5 100 100 Mass Soil Absorbance 0,4624 0,334 0,4468 0,316 0,5654 0,405 0,5210 0,375 0,5607 0,397 0,4807 0,341 Absorbance -0,008 0,188 0,416 1,016 ...
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Clari
School: Cornell University

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