Questions and Answers of Quantitative Chemical Analysis

Two peaks emerge from a chromatography column as sketched in the following illustration.where N is the number of theoretical plates and γ is the separation factor, defined as the quotient of linear
Until the 1960s, dinosaurs were thought to be cold-blooded animals, which means they could not regulate their body temperature. Reference 1 describes how the 18O/16O ratio in dinosaur bones suggests
Free cyanide in aqueous solution can be determined indirectly by atomic absorption on the basis of its ability to dissolve silver as it passes through a porous silver membrane filter at pH 12.A
Multivariate calibration. An important aspect of creating multivariate calibrations is selection of which and how many features (for example, wavelengths or wavenumbers) should be used to construct
Table 19-1 gives examples of standard methods for analyses using a spectrophotometric reaction.a. What is a standard method of analysis?b. U.S. Environmental Protection Agency method 350.1 for
In the chapter opener, trace metals in teeth and bone provide information about Otzi the Iceman’s diet and environment as a child and adult. The inorganic mineral matrix of teeth and bone is
What mass of sample in Figure 28-3 is expected to give a sampling standard deviation of ±6%?±6%?Figure 28-3 Counts per second per gram 290 250 210 170 Average = 237 0.1 10 K₂ Sample mass
Cloud-point extraction. Traces of lead in drinking water cause adverse health effects. The micelle-forming surfactant Triton X-114 (plus the co-surfactant cetyl trimethylammonium bromide) and a crown
From standard reduction potentials, which of the following metals would you expect to dissolve in HCl HCl by the reaction •''•[].. Zn, Fe, Co, Al, Hg, Cu, Pt, Au?Zn, Fe, Co, Al, Hg, Cu, Pt,
a. Describe the steps in QuEChERS and explain their purpose.b. Why is an internal standard used in QuEChERS?c. What is displayed in the total ion chromatogram in Figure 28-23?d. What is displayed in
Why doesn’t water produce 10-7MH+10-7 MH+ and 10-7MOH-10-7 MOH- when HBrHBr is added?
The figure shows the effect of pHpH on the response of a nitrite (NO2-) (NO-2) ion-selective electrode immersed in 1 μM NaNO2+1 mM NaCLl. 1 μM NaNO2+1 mM NaCLl. The authors recommend using the flat
a. Write the half-reactions for a H2-O2H2-O2 fuel cell. Find the theoretical cell voltage at 25°C 25°C if PH2=1.0 bar, PH2=1.0 bar, PO2=0.2 bar PO2=0.2 bar and [H+]=0.5 M[H+] = 0.5 M at both
Draw the structure of the predominant form of pyridoxal-55-phosphate at pH 7.00. pH 7.00.
Consider a reversible redox reaction at the surface of an electrode. “Reversible” means that the reaction is fast enough so that reactants and products maintain equilibrium at the electrode
Calculate αH2A,αH2A, αHA-, αHA- and aA2- αA2- for c is butenedioic acid at pH 1.00,1.92,6.00,6.27,and 10.00. pH 1.00, 1.92, 6.00, 6.27, and 10.00.
a. In Figure 17-20, is the reactant Fe(CN)63- Fe(CN)3-6 or Fe(CN)64-Fe(CN)4-6 at points b, c, and d? Write the order of decreasing concentration of reactant at the electrode surface at points b, c,
a. Why is square wave voltammetry more sensitive than sampled current voltammetry?b. Explain why the peak shape in square wave voltammetry is the derivative of the peak shape in sampled current
Consider the titration of 100.0 mL100.0 mL of 0.0100 M 0.0100 M Ce4+Ce4+ in 1 MHC1O41 MHC1O4.i by 0.040 0 M 0.040 0 M Cu+Cu+ to give Ce3+Ce3+ and Cu2+Cu2+, using PtPt and saturated Ag | AgClAg | AgC|
Consider the titration of 25.0 mL25.0 mL of 0.050 0 M 0.050 0 M Sn2+Sn2+ with 0.100 M 0.100 M Fe3+Fe3+ in 1 M HCI M HCI to give Fe2+ Fe2+ and Sn4+, Sn4+ using PtPt and calomel electrodes.a.
Students at the Northern Alberta Institute of Technology developed a spectrophotometric method for the simultaneous determination of acetylsalicylic acid (ASA), acetaminophen (ACE), and caffeine
A 100-mL 100-mL sample of hard water containing magnesium and calcium was titrated as illustrated in Figure 18-10.It required 14.59 mL 14.59 mL of 10.83 mM 10.83 mM ethylenediaminetetraacetic acid
Briefly describe how the time-of-flight mass spectrometer in Figure 22-2 works. What is the benefit of the electrostatic mirror in Figure 22-20?Figure 22-2Figure 22-20 Grid 1 V₂ = 20 kV to 18
The absorbance of a 2.31 x 10-5 M 2.31x10-5 M solution of a compound is 0.822 0.822 at a wavelength of 266 nm 266 nm in a 1.000-cm 1.000-cm cell.a. Calculate the molar absorptivity at 266 nm.266
Which technique I to IV is best suited to each application below? Use each technique only once. Justify each choice in one sentence.I. ColorimeterII. Discrete analyzerIII. 96 96-Well microplateIV.
Forster resonance energy transfer. Spectra of six dyes are shown here. Select a suitable donor/acceptor pair for each analytical objective.a. Excitation at 488 nm 488 nm results in little
Figure 20-36 shows standard uncertainty for measurements of carbon monoxide using averaging times of 11 to 1 000 s. 1000 s.a. Figure 20-36 is a log-log plot. Read the standard uncertainty for 44 and
Literature problem. Vanadium alloys containing 3-5% 3-5% chromium and titanium are promising structural materials for fusion reactors. Mechanical and physical properties of the alloy depend on the
Literature problem. The development of antibody-functionalized gold nanoparticles as reagents for spectrophotometric methods is an active area of research. The sensitivity of these methods depends on
Select the fluorescent derivatization reagent from 1 to 3 for each of the following applications from the literature.a. Quantitation of thiols such as glutathione, cysteine, homocysteine, and
Stern-Volmer plot. The table shows intensity and lifetime data for luminescence of the ruthenium complex in Figure 19-21 for a range of oxygen concentrations.a. Why does the luminescence intensity
Based on Figure 21-6, what are the processes involved in atomic absorption of a solution of a metal ion? In atomic emission?Figure 21-6 Excitation MOH(g) MO(g) MOH*(g) MO*(g) Emission Flame Burner
What is the difference between luminescence, chemiluminescence, and bioluminescence?
Blank solutions were monitored for vanadium as 51V+ 51V+ using inductively coupled plasma-mass spectrometry with the following results. a. Is the HClHCl used to prepare the blank solutions
Calibration curve. Figure 21-30 describes graphite furnace atomic absorbance determination of silver within individual Daphnia magna. Calibration data at 328.068 nn 328.068 nn is shown below.a.
In the spectrum below, identify as many peaks as you can in the X-ray fluorescence spectrum of soil from the location where water from the roof of a house drips onto the ground. For each KαKα peak,
a. Explain the purpose of the collision cell in Figure 21-28.b. Determination of 28Si 28Si ,< experiences isobaric interference from 14N2+ 14N+2 and background silicon leached from glass
Ayurveda is a form of medicine practiced in India. In one study, 20%20%. of U.S. and Indian-manufactured Ayurvedic medicines purchased through the Internet in 2005 contained detectable levels of
Signal in attenuated total reflectance is related to penetration depth.a. Calculate the penetration depth of 1 500 cm-1 1500 cm-1 radiation into an organic sample (n2=1.5)(n2=1.5) for a 45°450°
Literature problem. Over 2525 elements are essential to life. In J. Anal. Atom. Spec. 2018, 33, 1196, Open Access, Q. Zhang et al. developed a method to simultaneously quantitate macro- and
Big data signal averaging. Download the spreadsheet of ten fluorescence emission spectra for 1 μM1 μM anthracene in methanol from SaplingPlus or macmillanlearning.com.a. Data inspection. Before
Literature problem. Zinc is an essential micronutrient. It is estimated that 22 billon people are zinc deficient. B. J. Stevens et al. (Latin for “and others”) wrote a Technical Note (J. Anal.
Formaldehyde has a nominal (integer) mass of 30 Da, 30 Da, but its mass spectrum in Figure 22-7 has seven peaks at different values of m/z m/z. Explain the origin of each peak. Draw a Lewis dot
Explain why formation of volatile arsine (AsH3) (AsH3) improves detection limits versus direct nebulization of an arsenic solution.
a. Figure 22-27 is a high-resolution mass spectrum with a parent ion C8H11N4O2+ C8H11N4O+2 at m/z 195.087 55. m/z 195.087 55. Isotopic masses in Table 22-1 give m/z=195.087 63m/z = 195.087 63 for
What is the purpose of a matrix-matched standard in laser-ablation spectroscopy?
Resolving power of an Orbitrap mass spectrometer can be increased by allowing more time for acquisition. Two closely spaced peaks that are resolved in the lower spectrum overlap in the upper
In Figure 22-14, the sucralose species with a nominal mass X=395 X=395 is [12C121H1816O835C13]-. [12C121H1816O835Cl3]-. X+1X + 1 arises from isotopologues containing one 13C,13C, one 2H,2H, or
Dioctyl phthalate is a ubiquitous background substance in most labs because it is a plasticizer used in Tygon tubing.a. Suggest a structure for the base peak cation at m/z 149 m/z 149 and the second
When looking at the mass spectrum of an unknown substance, you tentatively identify the molecular ion MM as the peak with the most significant intensity at the high-mass end of the spectrum. Then you
Calculate the theoretical masses of the sucralose species in Figure 22-14 at nominal masses of 395,395, 397,397, 399,399 and 401.401. Find the difference in ppm between observed and calculated
Mass spectral interpretation. The compound C9H4N2Cl6 C9H4N2Cl6 is a by-product found in chlorinated pesticides.a. Verify that the formula for rings + double bonds agrees with the structure.b. Find
Nanoparticles with a gold core and organothiol outer shell with well-defined stoichiometries Aux(SR)yAux(SR)y i can be prepared and isolated.a. The MALDI-time-of-flight mass spectrum of the
Alkanes do not ordinarily exhibit a molecular ion M+.M+. in the electron ionization mass spectrum because M+.M+. breaks into fragments. If dilute alkane vapor in HeHe is allowed to expand through a
Tandem mass tags. Tags A, B, and C in Figure 22-41 with nominal m/z 116 m/z 116 reporter ions are members of a set of 1212 tags accessible by certain synthetic pathways.a. Explain the functions of
Figure 5-9 is a chromatogram of component XX and internal standard SS. The small peak early in the chromatogram is an unretained component.a. What is the linear velocity if the column length is 100
The distribution constant for a solute in chromatography is KD=[S]S/[S]M, KD=[S]g/[S]M, where [S]S[S]S is the concentration in the stationary phase and [S]M[S]M is the concentration in the mobile
What is the optimal linear velocity in Figure 23-17 for best separation of solutes?Figure 23-17 Plate height (um) 12 10 co 2 0 A+ Blu, + Cu Mass transfer Longitudinal diffusion Cux Multiple paths A 1
Which of the following columns will provide:a. Highest plate number?b. Greatest retention?c. Highest separation factor?d. Best separation?Column 1: N=1 000; N = 1 000; k2=1.2; k2=1.2; α =1.16;α =
Resolution with HPLC Teaching Assistant, an Excel spreadsheet that simulates high performance liquid chromatography separations. Download the Excel file from SaplingPlus, macmillanlearning.com, or
For the separation of A and B by column 22 in the previous problem:a. If broadening is mainly due to longitudinal diffusion, how should the flow rate be changed to improve resolution?b. If broadening
a. Two chromatographic peaks with average widths, wav,wav, of 6 min 6 min are eluted at 2424 and 29 min. 29 min. Which diagram in Figure 23-10 will most closely resemble the chromatogram?b. Two
Which column is more efficient: plate height=0.1 mm plate height=0.1 mm or plate height=1 mm? plate height = 1 mm?
a. If retention times in Figure 23-7 are 1.0 min 1.0 min for CH4,CH4, 12.0 min 12.0 min for octane, 13.0 min 13.0 min for unknown, and 15.0 min 15.0 min for nonane, find the Kovats retention index
Match descriptions 1-5 1-5 with the band broadening terms in the second list.1. Depends on radius of open tubular column2. Not present in an open tubular column3. Depends on length and radius of
a. One microliter of 0.1 μg/mL 0.1 μg/mL benzene is injected into a gas chromatograph using splitless injection. How much benzene is loaded onto the column?b. How much benzene is loaded onto the
Efficiency with HPLC Teaching Assistant, an Excel simulation of high performance liquid chromatography.Download the Excel file from SaplingPlus, macmillanlearning.com, or the link in reference 27,27.
a. Use Trouton’s rule, ΔHvap° ≈ (88 J mol-1 K-1) ΔH°vap ≈ (88 J mol-1 K-1) to estimate the enthalpy of vaporization of octane (b.p. 126°C). (b.p. 126°C)b. Use the form of the
How does pyrolysis gas chromatography allow characterization and quantitation of nonvolatile analytes such as microplastics in the environment?
The figure shows band broadening behavior for helium for open tubular columns of different inner diameter.a. Why does high linear velocity affect plate height more for the wider diameter column?b.
In the analysis of odorants in tequila in Figure 24-21, tequila was diluted with water and extracted four times with dichloromethane (CH2Cl2, (CH2Cl2, b.p. 40°C)40°C). The 400 mL 400 mL of
a. UHPLC can provide exquisite resolution when run on long columns at high pressure or rapid separations with reasonable resolution if short columns are run fast. The drug acetaminophen run on a
a. Use Figure 25-31 to select a tetrahydrofuran/water tetrahydrofuran/water mobile phase strength equivalent to the strength of 80% 80% methanol.b. Describe how to prepare 1 liter of this
The figure shows reversed-phase retention data for three compounds.a. Identify whether compounds A, B, and C are weak acids or bases. For each compound, what is the pKapKa and the retention
Use Figure 25-33 for the following questions:a. What pHpH would be best for the separation of benzoic acid, 4-4-nitrophenol, and 3-3-methylbenzoic acid?b. What pHpH would be best for the separation
Simulating a separation with a spreadsheet. Use the spreadsheet in Figure 25-39 to simulate the chromatograms for Ф=0.75Ф= 0.75 and Ф=0.56Ф= 0.56 in Figure 25-40.Figure 25-39Figure 25-40 A 1
Consider the separation of inorganic and organic anions in Figure 26-7.a. What is the probable charge (Xn-) (Xn-)of pyruvate (peak 1010), 2-2-oxovalerate (peak 1616), and maleate (peak 2828)?b.
Isocratic separation with HPLC Teaching Assistant, an Excel spreadsheet that simulates a reversed-phase liquid chromatographic separation. Download the Excel file from SaplingPlus,
Low iron concentration (as low as 0.02 nM 0.02 nM) in the open ocean limits phytoplankton growth. Preconcentration is required to determine such low concentrations. Trace Fe3+Fe3+ from a large volume
a. The suppressor in Figure 26-8 enables low parts per billion conductivity detection for anions such as Cl-Cl- and Br-,Br-. but very poor detection limits for anions such as CN-CN- and borate.
Conductivity and contactless conductivity detectors were developed for suppressed capillary ion chromatography. Observed peak heights in millivolts for bromide standards are in the table.a. Use Excel
a. The interstitial volume, Vo,Vo, in Figure 26-14 is the volume at which the curves rise vertically at the left. Find VoVo for the 25-nm-pore-size 25-nm-pore-size column. To the nearest order of
What is mixed-mode chromatography? How does it differ from ion-pair chromatography?
Electrophoretic mobility of the anionic form A-A- of the weak acid phenol (HA=C6H5OH) (HA=C6H5OH) and its derivatives are:a. Explain the trend in electrophoretic mobility from phenol to
Some “bath salts” are synthetic cathinones designed to circumvent laws, but have unknown properties and side effects. The acid dissociation constant affects the toxicology of the derivatives.
Figure 26-22 shows the separation of substituted benzoates. There is a peak of unknown identity at 86.0 s.86.0 s.a. Is the unknown a cation, neutral, or an anion?b. Find the apparent mobility and
What is electroosmosis?
Corrected peak area. A micellar electrokinetic chromatography method for phthalazine and its metabolite 1-1- phthalazinone yielded the following repeatability for six replicate injections of a 50 μM
What is the purpose of the WO3WO3 and CuCu in Figure 27-8?Figure 27-8 Leee Oxygen WO oxidation catalyst Cu reduction catalyst and O₂ scavenger 7. Encapsulated
Write a balanced equation for combustion of C8H7NO2SBrCl C8H7NO2SBrCl in a C,C,H,H,N,N,SS elemental analyzer.
The chart shows average CO2CO2 emissions for fossil fuel vehicles (gasoline, diesel, and hybrid gas-electric), as well as electric vehicles. The abscissa is mg CO2CO2 per mile driven per pound mass
A 70-kg 70-kg adult can die from injection of ~100 ng ~ 100 ng of botulinum neurotoxin or by inhaling -1 ug ~ 1 ug of the toxin. A sensitive assay for the neurotoxin can detect -200pg/mL~200pg/niL in
How many significant figures are there in the following numbers?a. 1.903 01.903 0b. 0.039 100.039 10c. 1.40 x104 1.40 x 104
Write the mass ofa. SrF2SrF2b. Na2CO3Na2CO2 with a reasonable number of digits. Use the periodic table inside the cover of this book to find atomic mass.
Propose a method to remove the systematic error from each of these cases.a. Pentane (density=0.626g/mL)(density=0.626 g/mL) is weighed on an analytical balance.b. A pipet which delivers a nominal
Haymitch, Gale, Katniss, and Peeta shot the following targets in an archery contest. Match each target with the proper description.a. Accurate and preciseb. Accurate but not precisec. Precise but not
Verify the following calculations:a. 3.1415 (±0.0011)=1.772 4 (±0.000 3) √3.141 5 (±0.0011) = 1.772 4 (±0.0003)b. log[3.141 5 (±0.001 1)]=0.497 14 (±0.000 15)log[3.141 5 (±0.0011)] = 0.49714
A chemistry parable. A tortoise and hare decided to take quantitative analysis. (I don’t know why either.) In the first hour the hare did 10 10 titrations with a standard deviation s of 1.5%1.5%.
Probability theory states that for the tosses of sets of 50 coins50 coins in Figure 4-1, the population mean μ = 25.00 μ = 25.00 and the population standard deviation = 3.54 deviation = 3.54a. Use
The U.S. Food and Drug Administration requires that calcium content of food be reported. The mean content (mg/g) (mg/g) and standard deviation (±s) (±s) for triplicate (n=3)(n=3) determinations

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