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Study Resources (Chemistry)

  13.The following data was generated as part of the calibration of a mass spectrometer to be used for a morphine assay. [morphine] ppb area counts (extracted ion) 20.0 1400 80.0 6108 150.0 12419 250.0 17009 400.0 30072 600.0 42393 800.0 64098 The analyst runs an independent calibration check sample with an accepted true value of 100.0 ppb of morphine and obtains 7084 counts for the area of the.
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  1.Explain the difference between molarity and molality. 2.Explain why salt is placed on icy sidewalks in the winter. 3.A solution is prepared by mixing 3.62 g of an unknown electrolyte with 285.0 g of chloroform. The freezing point of the solution is –64.2 oC. (The normal freezing point for chloroform is.
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  1.What levels of quality assurance are there in typical freshman chemistry labs?  Organic labs? 2.Draw a diagram that employs two Gaussian curves to illustrate the concept of bias. What does this have in common with the t-test of means introduced in the previous chapter? In what ways does it differ?   .
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  4.A toxicology laboratory associated with a state Medical Examiner’s office purchases a new type of extraction system with the hope of improving on their current method of screening for fentanyl in post-mortem blood samples.   To validate the change, they run 20 samples using the older extraction method and the same.
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  8.  Agents of the Drug Enforcement Administration seize 5000 1-kg “bricks” containing a light tan powder that is suspected to contain heroin.  Historically, such seizures are all pure heroin.  Outwardly, all the packages appear similar. a)Use the ENFSI spreadsheet to select the number of samples that need to be collected and.
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1.Review the propagation of uncertainty calculations shown in Chapter 2.  When the uncertainty is derived as the square root of the sum of squares, what implicit assumption is being made regarding the individual contributors and their distributions?  What problems might this assumption present? 2.How is the propagation of error method (Chapter.
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  3.A forensic toxicologist receives a postmortem blood sample and performs a routine screening analysis followed by GC/MS to confirm the presence of cocaine and its metabolites. The toxicologist also performs a quantitative analysis for these analytes. He writes his report, sends it through the lab system, and it arrives on.
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  1.What is a primary standard? 2.The equation below represents the titration that will be completed in Experiment 24. It is sometimes called a redox titration because an oxidation-reduction reaction occurs. What is the reducing agent? The oxidizing reagent? Explain your answers. 3.In solution, the ferrioxalate complex undergoes photoreduction. The complex absorbs a.
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  1.Look up the Ksp values for the following compounds: lead (II) sulfate, aluminum hydroxide, silver chloride, silver bromide, and copper sulfide.  Which one is most soluble? Least soluble? Explain. 2.A student is curious about the Ksp value for NaCl.  The student looks up the value in the appendix of his textbook.
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  1.A reaction of 7.2 mL of iron (III) chloride solution (0.40 g/mL) and 8.95 g of K2C2O4•H2O produced 6.22 g of K3Fe(C2O4)3•3 H2O. Determine the limiting reagent, and calculate the percent yield of the synthesis. 2.Draw the structure of K3Fe(C2O4)3•3 H2O. 3.Explain the difference between precipitation and recrystallization.     .
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  8.A forensic laboratory operates in an older building in which the environmental systems are poorly controlled.  In winter, the lab tends to overheat into the 90s(?F) while in summer, the air conditioning can drive temperatures into the low 60s (?F).  What figure(s) of merit will be impacted? 9.If you had to.
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  7.Using the hypergeometric function in Excel, calculate the following probabilities and report as a percentage as a “1 in X” odds a)Drawing the four playing cards from a shuffled deck and getting all aces b)Dividing a full shuffled deck in half and having all four queens in one pile c)Dividing a full shuffled.
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  1.Anthocyanins are a class of compounds found in many berries and other fruits. Draw the general structure and indicate the structural component responsible for creating color. 2.Give a biological application of methyl green. 3.Define Lewis acid and Lewis base. 4.What does it mean for a reaction to be pseudo-first order?.
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  7.A forensic chemist prepares a standard of caffeine in chloroform for use in a quantitative assay.  The caffeine is purchased from a reputable supply house and arrives with a certificate stating that it is 99.5% pure or better.  The analyst needs to make a stock solution at a concentration near.
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  12.A laboratory generates the following data for a morphine assay.  Construct an external standard curve and complete the table that follows the curve data. [morphine], ppb area counts (extracted ion) 20.0 1452 80.0 6108 150.0 11309 250.0 17009 400.0 30072 600.0 44567 800.0 61234 Data table to complete:   .
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  3.In complex environmental samples such as soils, spikes are used to measure the matrix effect. The range of allowable recoveries for 1,2-dichloroethane-d4, a spike compound, is 80–120%. How is it possible to obtain a recovery of greater than 100%? Hint: This happens frequently and it does not imply that this.
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  5.Deuterated compounds are useful as internal standards, while isotopes such as 14C or tritium are not. Why? 6.The following data is produced as part of a laboratory accreditation check sample. Critique the results. “[]” is the concentration ratio. ppb codeine Peak area ppb IS Peak area [ ] ratio area ratio 15.0 9599 50.0 29933 0.30 0.32 35.0 21456 50.0 30099 0.70 0.71 75.0 45326 50.0 32051 1.50 1.41 125.0 82100 50.0 32912 2.50 2.49 150.0 95003 50.0 31100 3.00 3.05 200.0 122409 50.0 30303 4.00 4.04             Blank: 3100 50.0 31954     Known (100.0 +/- 1.0 ppb): 51208 50.0 33000     Cal check (Independent, 125.0           +/-0.1.
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  1.A great scientist can still be a terrible forensic scientist; a person who gives wonderful testimony can be a terrible forensic scientist. Comment on these observations and the implication for forensic chemistry. 2.Can jurors ask questions of expert witnesses? Comment on your findings regarding this issue.   .
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  2.A micropipette is certified by the manufacturer at 50.0μL TD, +/- 1.5% (95% confidence).  An analyst performs a routine calibration check by pipetting a series of 5 aliquots of DI water into a tared vial. The water is at a temperature of 25.0°C. The following data is obtained: n Weight (cumulative), g 1 0.0494 2 0.0997 3 0.1484 4 0.1985 5 0.2477   Is.
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  10.A laboratory analyzes the CRM 1511 (Figure 3.5) and generates data for all components.  Complete the table: NOTE: ERROR IN THE FIRST PRINTING OF THE TEXT; See below.   mmole/L x 10-4 mmole/L x 10-3   Analyte Certified value Laboratory value Bias %error Morphine 1.08 1.00 -0.90 -8.3 Codeine 9.62 9.50 -1.20 -1.2 Benzoylecgonine 3.60 3.72 1.20 3.3 THC-9-COOH 4.09 4.25 1.60 3.9 Phencyclidine 9.74 9.74 -6.70 -6.9 Can you calculate the accuracy in this case? Why or why not? 11.Suppose the analyst who did the analysis.
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  8. A forensic toxicology laboratory associated with a Medical Examiner’s Office routinely screens post-mortem blood samples for morphine, which is a metabolite of heroin.  To address the difficult matrix, the laboratory uses an internal standard method.  The following curve was generated for a typical assay: [morphine] ppb area counts [IS] (ppb) area counts 20.0 1452 250 15023 80.0 6108 250 15865 150.0 13309 250 14998 250.0 17009 250 15000 400.0 30072 250 15299 600.0 42234 250 15308 800.0 61234 250 15333   The.
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  1.This chapter focused on uncertainty of quantitative measurements.  Do qualitative measurements, such as a color test for blood, have an associated uncertainty?  How would you estimate it quantitatively? 2.For the buoyancy issue in weighing, the statement was made that the conservative approach was appropriate to the forensic laboratory.  What does this.
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  7.  A laboratory creates a control chart for an analytical balance by weighing a certified, traceable weight of 20.00 mg each week for a year.  Enter the following data into an Excel spreadsheet (two column format) and answer the following questions: First Quarter (Q1)   Q2 Q3   Q4 Week Weight # Week # Weight Week # Weight Week # Weight 1 19.91 14 20.04 27 20.03   40 20.02 2 20.10 15 20.00 28 20.14   41.
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  9.In the scenario presented in Figure 2.5 and discussed in the section 2.5, would it matter if the data is normally distributed for application of a hypothesis test? 10.Using the Excel functions of skewness and kurtosis, calculate these values for each data set and comment on the meaning.   Are either, neither,.
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  1.Is the analysis of drugs using instruments such as mass spectrometers and infrared spectrometry based on comparison? 2.How important is the way in which scientific evidence is presented? Comment on the relative importance of content versus presentation. Why is learning how to testify such an important skill?   .
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  14.Why are deuterated compounds frequently used as internal standards? 15.If an analyst inadvertently generates a least squared fit calibration curve that is forced through the origin, what type of error would be introduced? Would accuracy or precision be affected? What types of QA/QC samples and procedures could identify this error?   .
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  2.What is the difference between a confidence level and a probability? 3.A university instructs its professors to assign grades in the range of 0.0 for an F to 4.0 for an A+. The letter grade is not recorded, only the number. When students’ GPAs are calculated, they are reported with three decimal.
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