_ chemical analysis is the measurement of how much of a chemical substance is present. __________ chemical analysis is the determination of what is present in a sample.
a.
Quantitative; Qualitative
b.
Stoichiometric; Qualitative
c.
Qualitative; Quantitative
d.
Stoichiometric; Identification
e.
Quantitative; Identification
ANSWER:
a
2. Which of the following analyses is NOT quantitative?
A home pregnancy test.
A chocolate bar contains 33% fat.
The density of water is determined to be 1.0 g/mL at 4ºC.
A tap water sample was found to contain 13 200 ppb Pb^{2+}.
A driver had 0.12% alcohol in his bloodstream.
3. Chemical Abstract is the most comprehensive source for locating articles published in chemistry journals. ___________ is software that accesses Chemical Abstract.
Google Scholar
SciFinder
Web of Science
Wikipedia
Microsoft Office
b
4. Sampling is the process in which
general questions are translated into specific questions to be answered through chemical measurements.
the chemical literature is searched to find appropriate procedures or, if necessary, devise new procedures to make the required measurements.
a representative material is selected to analyze.
a representative sample is converted into a form suitable for analysis.
the concentration of analyte is measured in several identical portions.
c
5. A sample with a uniform chemical composition is a ___________ sample.
homologous
homogeneous
uniform
consistent
heterogeneous
6. A(n) __________ sample is a sample in which the chemical composition differs from place to place.
variable
random
inconsistent
e
7. When extracting a sample with a liquid, the liquid is __________ from the sample.
transferred
drained
decanted
effused
dispensed
8. A(n) _____________ is used to grind solids into smaller particles.
orbital shaker
vortexer
mixer
mortar and pestle
centrifuge
d
9. ______________ is the substance being measured during a chemical analysis.
Bulk
Lot
Sample
Analyte
Aliquot
10. The liquid above the packed solid following a centrifugation is the ___________.
solvonatant
analyte
serum
supernatant
11. A(n) __________ is a suspension of a solid in a liquid.
slurry
colloid
gel
allotrope
12. ____________ is the series of procedures applied to a sample prior to analysis.
Preanalysis clean up
Sample preparation
Filler elimination
Matrix removal
Lot cleaning
13. An aliquot is
a portion of a larger whole, especially a sample taken for chemical analysis or other treatment.
the substance being measured.
a suspension of a solid in a liquid.
the decanted liquid following a centrifugation.
the liquid above the packed solid following a centrifugation.
14. For separations performed using a chromatography column, the plot of detector response versus time is a(n) __________, and the area under the peak is _________ to the quantity of compound passing through the detector.
column plot; proportional
column plot; inversely proportional
chromatogram; proportional
chromatogram; inversely proportional
absorbance spectrum; proportional
15. A(n) ___________ is a plot of detector response as a function of analyte concentration. The curve is constructed using ___________ containing known concentrations of the analyte of interest.
analyte curve; response solutions
response curve; standard solutions
analyte curve; analyte solutions
calibration curve; standard solutions
response curve; response solutions
16. ______________ is the process of procuring a representative sample to analyze.
Inspection
Examination
Representation
Sampling
Partaking
17. Solid-phase extraction is a sample preparation technique. Which statement(s) is/are NOT true for an aqueous solid-phase extraction?
III
I
II and III
IV
II
18. Which is NOT a general step in the analytical process?
sample preparation
selecting an analytical procedure
making policy
reporting and interpretation
analysis
19. The purpose of replicate measurements is to assess the __________ in the analysis and to guard against __________ in the analysis of a single aliquot.
error; uncertainty
variability; gross error
uncertainty; precision
error; accuracy
accuracy; error
20. __________ are repeated measurements to assess variability in an analysis and to guard against gross error in the analysis of a single aliquot.
Replicate measurements
Aliquots
Analysis
Error measurements
21. Which statement is NOT true?
For a random heterogeneous material, differences in composition are random and on a fine scale.
A representative random sample is collected from randomly selected portions of the sample for a given number of times.
Segregated heterogeneous material has large regions with obviously different compositions.
A representative composite sample is collected from a segregated material by taking portions from each region, where the number of collected portions are proportional to the area of the region.
All are true statements.
22. __________ occurs when a species other than analyte increases or decreases the analytical signal and makes it appear that the concentration is greater or less than the real concentration.
Interference
Masking
Disruption
Intervention
23. __________ is the transformation of an interfering species into a form that is not detected.
Obscurance
Cloaking
Camouflaging
24. Ca^{2+} in lake water can be measured with a reagent called EDTA. However, the presence of Al^{3+} will provide a false signal because it reacts with EDTA as well. The method of adding excess F^{−} to minimize the effects of Al^{3+} on the Ca^{2+} determination is called
interference.
masking.
obscurance.
cloaking.
camouflaging.
25. Chemists use the term __________ to refer any chemical of interest.
species
replicate
aliquot
bulk
26. A calibration curve for the determination of aspirin is constructed from known concentration aspirin solutions (mg/mL) and the HPLC peak areas for each standard. If the equation of the best-fit line is y = 12.565x − 0.71, what is the concentration for an unknown that has a peak area of 83.5?
6.70 mg/mL; Substitute y = 83.5 into y = 12.565x − 0.71 and solve for x.
27. The allicin concentration in a garlic extract sample was determined using HPLC. A calibration curve prepared using allicin standards of known concentration (M) has an equation of the best-fit line of y = 24 376x + 8.4. What is the molar concentration of allicin in the garlic extract sample if it has a signal of 88.9?
0.003 30 M; Substitute y = 88.9 into y = 24 376x + 8.4 and solve for x.
28. The spectrophotometric analysis of a series of permanganate standards (mM) at 525 nm gave a calibration equation of y = 2.492 5x + 0.091. If an unknown sample has an absorbance reading of 0.654, what is the millimolar concentration of permanganate in the unknown solution?
0.226 mM; Substitute y = 0.654 into y = 2.492 5x + 0.091 and solve for x.
29. The fluorescence quantum yield measurement results of quinine sulfate in 0.1 M H_{2}SO_{4} solution showed that there was a linear relationship between the integrated photoluminescence intensity and absorbance of quinine sulfate. The relationship is described by the equation y = 1.28 ´ 10^{8}x – 780 102, where y is the integrated photoluminescence intensity and x is the absorbance of quinine sulfate. If the sample has an absorbance of 0.045, what is its photoluminescence intensity?
4.98 × 10^{6}; Substitute x = 0.045 into y = 1.28 × 10^{8}x – 780 102 and solve for y.
30. Inorganic anions can be analyzed by capillary electrophoresis with conductivity detection. A calibration curve for nitrate was constructed by plotting the signal (μV) as a function of nitration concentration (μM), resulting in an equation of y = 498x + 3.28. If a sample contains 62.5 mM nitrate ions, what would be the signal of nitrate in the sample?
3.11 × 10^{4}μV or 31.1 mV; Substitute x = 62.5 into y = 498x + 3.28 and solve for y.
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