ANAL CHEM 1 Flashcards
When potassium iodide reacts with lead(II) nitrate, a yellow precipitate (PbI2) is produced. If 0.78 g of lead(II) iodide was produced, how many grams of lead(II) nitrate was used? You may assume the reaction yield was 100%, and an excess of potassium iodide was used.
0.78 g
1.6 g
0.46 g
0.56 g
Not enough information is given.
0.56 g
If 4.94 grams of KOH is dissolved in water to make a final volume of 2.0 L, what is the molarity of the solution?
- 088 M
- 044 M
- 5 M
- 025 M
- 18 M
0.044 M
If 21.3 g of glucose (C6H12O6) is dissolved in 5.00 L of deionized water, what is the molality of the solution? (The density of water is 1.00 g/mL.)
- 0237 m
- 592 m
- 118 m
- 26 m
- 00426 m
0.0237 m
Which of the following is the equivalent of 4.3 ppm sodium ion (Na+) concentration?
0.0043 ppb
0.043 ppb
430 ppb
4300 ppb
None of the above
4300 ppb
How many milliliters of a 0.100 M potassium permanganate stock solution would be needed to make 100 mL of 0.0250 M potassium permanganate?
- 0 mL
- 00 mL
- 00 mL
- 50 mL
- 0 mL
25.0 mL
The concentration of a solution is known to be 0.101 M. A student determines the concentration to be 0.088 M, 0.087 M, and 0.089 M for each titration performed. Which of the following best describes these results?
The results are accurate but not precise.
The results are precise but not accurate
The results are neither accurate nor precise.
The results are both accurate and precise.
The results are not enough information is given to determine accuracy or precision.
The results are precise but not accurate
Concentrated hydrochloric acid is 12 M and has a density of 1.18 g/mL. What is the weight percent (% w/w) of concentrated HCl?
14% 5.1% 12% 98% 37%
37%
A stock solution of sodium acetate is 1.0 M. To make Solution A, 2.00 mL of the stock solution is transferred and diluted to a total volume of 100 mL. Solution B is made by transferring 5.0 mL of Solution A and diluting it to a total volume of 250 mL. Solution C is made by transferring 1.0 mL of Solution B and diluting it to a total volume of 25 mL. What is the concentration of solution C?
1.6 µM 16 µM 1.6 mM 0.16 mM None of the above
16 µM
The equation for a normal calibration curve for the detection of iron(II) is determined experimentally to be: S = 12.93 M - 1 * C + 0.0017. Analysis of a sample with unknown concentration gives an absorbance reading of 0.106. What is the concentration of iron(II) in the unknown?
- 37 M
- 50 mM
- 90 mM
- 06 mM
- 83 mM
8.06 mM
When performing calculations for standard additions, which of the following must be true?
The volume of the standard added must be added with the volume of the sample used to give a new sample volume.
The volume of the standard added is subtracted from the total volume of the sample used.
The volume of the standard added can be ignored, because it is so small.
The volume of the standard added can be ignored, because volumes are not used in the calculations.
The volume of the standard added can be ignored, because it is part of the blank correction.
The volume of the standard added must be added with the volume of the sample used to give a new sample volume.
Which of the following statements about the sensitivity of an analytical method is true?
The sensitivity of an analytical method is the same as its detection limit.
The sensitivity of an analytical method is a measure of ability to determine whether slight differences in experimental results are significant.
The sensitivity of an analytical method is the smallest amount of analyte that the instrument is able to measure.
The sensitivity of an analytical method is the response of the instrument to human error.
None of the above
The sensitivity of an analytical method is a measure of ability to determine whether slight differences in experimental results are significant.
Which of the following statements is true of the detection limit of an instrument?
The detection limit of an instrument is the same as its sensitivity.
The detection limit of an instrument is a measure of ability to determine whether slight differences in experimental results are significant.
The detection limit of an instrument is the smallest amount of analyte that the instrument is able to measure.
The detection limit of an instrument is the ability of the instrument to respond to an error.
None of the above
The detection limit of an instrument is the smallest amount of analyte that the instrument is able to measure.
Fill in the blank. Precipitation, volatilization, and particulation are all types of ____________________.
Electrochemical analysis methods Gravimetric analysis methods Tritrimetric analysis methods Spectroscopic analysis methods Photochemical analysis methods
Gravimetric analysis methods
Fill in the blank. Gravimetric analysis relies heavily on the principle of __________________.
Conservation of energy Conservation of mass Constant compostition Definite proportions The law of gravity
Conservation of mass
are a common problem in gravimetric analysis, but can be controlled by which of the following?
Carefully controlling the solution conditions
Reprecipitation of the solid
Digestion of the precipitate
Thoroughly washing and drying the filtrate
All of the above
All of the above
Volatilization gravimetry would be most useful in determining which of the following?
The amount of silver in a solution of silver nitrate The acidity of a water sample The amount of water in eposom salts All of the above None of the above
The amount of water in eposom salts
Which of the following statements about the equivalence point of an acid-base titration is true?
The equivalence point of an acid-base titration is the same as the indicator endpoint.
The equivalence point of an acid-base titration is the point where there is an equivalent amount of titrant and titrand.
The equivalence point of an acid-base titration is where the pH = 7.0 (neutral).
The equivalence point of an acid-base titration is where the entire volume of the buret has been used.
The equivalence point of an acid-base titration is the average value of the dissociation constants.
The equivalence point of an acid-base titration is the point where there is an equivalent amount of titrant and titrand.
What is the stoichiometry of EDTA with metal ions?
It is 1:6, because EDTA is a hexaprotic weak acid with six distinct acid dissociation values.
It is 1:4, because EDTA has four binding sites upon loss of the four carboxylic acid protons.
It is 1:2, because EDTA has two binding sites upon loss of the two ammonium protons.
It is 1:1, because EDTA forms a cage-like structure around the metal ion.
It is dependent on the metal ion present.
It is 1:1, because EDTA forms a cage-like structure around the metal ion.
A 58.3 mg sample containing Sn2+ is dissolved in 1.0 M HCl. If 23.6 mL of 0.010 M Tl3+ was required to titrate to endpoint, what is the mass percent (w/w%) of tin in the original sample?
48% 28% 24% 40% 14%
48%
A 0.357 g sample contains only lead(II) iodide and sodium iodide in 100 mL of distilled water. Titration to the Fajan’s end point requires 22.37 mL of 0.050 M silver nitrate. What is the mass percent (w/w%) of lead(II) iodide in the sample?
18% 36% 1.6% 53% 47%
53%
Which variable in Beer’s law represents how well a chemical species absorbs light at a given wavelength?
c - concentration ε - molar absorptivity coefficient A - absorbance b - path length of the sample λ - wavelength
ε - molar absorptivity coefficient
According to Beer’s Law, what happens to the absorbance reading if the concentration of the solution is halved?
The absorbance will double.
The absorbance will quadruple.
The absorbance will be halved.
The absorbance will be quartered.
There is no way to tell, because concentration and absorbance are not a linear relationship.
The absorbance will be halved.
Why must solutions with high concentrations be diluted prior to analysis via Beer’s Law?
The relationship between absorbance and concentration is not linear at high concentrations.
The detector will reach its detection threshhold.
The photon source is too weak to provide accurate results.
The molar absorptivity of a compound is dependent on its concentration.
There is no need to work with dilute concentrations; any concentration will work.
The relationship between absorbance and concentration is not linear at high concentrations
Which of the following transitions is NOT possible in UV-Vis absorption?
σ → σ*
σ → n
σ → π*
n → π*
σ → π*
Which of the following typically exhibits the largest molar absorptivities?
σ → σ* absorbances σ → n absorbances σ* → π* absorbances π → π* absorbances Metal to ligand charge transfer (MLCT) absorbances
Metal to ligand charge transfer (MLCT) absorbances
Which of the following is the correct order in which light passes through a UV-Vis spectrometer?
Detector, sample, source, monochromator Source, monochromator, sample, detector Source, sample, monochromator, detector Monochromator, source, sample, detector Sample, source, monochromator, detector
Source, monochromator, sample, detector
What is the purpose of a monochromator?
To remove stray light from the room
To serve as a polychromatic light source
To interpret the photon signal into a digital readout
To allow only light of a certain wavelength to pass from the source to the sample
To focus light from the sample onto the detector
To allow only light of a certain wavelength to pass from the source to the sample
The regression line from a plot of absorbance vs. concentration yields: A = 2.31 c + 0.002. If the absorbance of an unknown is measured to be 0.124, what is the concentration of the analyte?
- 29 M
- 053 M
- 86 M
- 093 M
- 43 M
0.053 M
The method of continuous variations, also known as Job’s method, uses the intersection of the ligand-line and the metal-line to determine which of the following?
The concentration at which the detector can no longer respond to the signal
The mole ratio between the metal and ligand in a complex
The maximum intensity of source photons transmitted
The number of dimeric molecules formed
The oxidation number of the metal
The mole ratio between the metal and ligand in a complex
Ultraviolet and visible radiationaffect which of the following?
Core electrons Valence electrons Nuclear spin Molecular vibrations Molecular rotations
Valence electrons
Infrared radiation affects which of the following?
Core electrons Valence electrons Molecular vibrations Molecular rotations Nuclear spin
Molecular vibrations
Complete the sentence. All of the following are used to describe the bending modes in infrared spectroscopy, EXCEPT:
In-plane rocking. In-plane scissoring. Assymetric stretching. Out-of-plane twisting. Out-of-plane wagging.
Assymetric stretching.
What is the advantage of using a silver chloride sample cell rather than a sodium chloride sample cell for IR spectroscopy?
Aquesous samples can be measured; AgCl is not water soluble.
There is no advantage.
Silver chloride does not absorb IR radiation.
Silver chloride is translucent.
Sodium chloride is less expensive.
Aquesous samples can be measured; AgCl is not water soluble.
In order for a compound to be IR active, it must undergo which of the following?
A change in polarizability A change in dipole moment Emission of an electron Transfer of an electon Metal-ligand charge transfer
A change in dipole moment
Complete the sentence. All of the following are infrared sources, EXCEPT:
The Nernst glower.
The Globar source.
An incandescent wire.
A pyroelectric glower.
A pyroelectric glower.
Complete the sentence. All of the following are detectors used in infrared spectroscopy, EXCEPT:
A charge-coupled diode.
A thermocouple.
A pyroelectric detector.
A photoelectric detector.
A charge-coupled diode.
Fill in the blank. NMR affects a molecule’s ________________.
Nuclear spin Valence electrons Core electrons Molecular vibrations Molecular rotations
Nuclear spin
In 1H-NMR spectroscopy, if a CH2 neighbors a CH3, the hydrogen nuclei of the CH3 will appear as which of the following?
A doublet, with a peak integration of 2 A doublet, with a peak integration of 3 A triplet, with a peak integration of 2 A triplet, with a peak integration of 3 A single peak, with an integration of 5
A triplet, with a peak integration of 3
Where does spin-lattice relaxation occur?
It occurs between neighboring nuclei with identical frequencies but different quantum states via energy transfer.
It occurs between the excited nuclei and nuclei within the sample matrix.
It occurs between atoms in the same molecule.
It occurs between the nuclei of the sample and the signal source.
All of the above
It occurs between the excited nuclei and nuclei within the sample matrix.
The value of the chemical shift in NMR spectroscopy is directly related to which of the following?
The amount of shielding The applied magnetic field The identity of the reference sample The electronegativity of the nucleus All of the above
All of the above
