Analytical Chemistry Test Questions & Answers Chapter 11 - Chemistry 3 4e | Test Bank Burrows by Andrew Burrows. DOCX document preview.
Chapter 11: Analytical Chemistry
Test Bank
Type: multiple choice question
Title: Chapter 11 Question 01
1) A set of supposedly identical solutions of the dye rhodamine 6G were prepared. The concentrations of the solutions were determined using spectrophotometry and were found to be normally distributed with a mean concentration of 12.672 mmol dm–3 and a standard deviation of 0.012 mmol dm–3. What proportion of the samples would be expected to have concentrations greater than 12.696 mmol dm–3?
Section reference: 11.1
a. 2.5%
b. 5.0%
c. 16.0%
d. 32.0%
Type: multiple choice question
Title: Chapter 11 Question 02
2) The limit for the detection of Cl– ions in a sample of mineral water through gravimetric analysis is quoted as 2.5 ppb by mass. Express this detection limit as a molar concentration of Cl– ions, given that the density of water is 1.00 g cm–3.
2.5 × 10-6 g = 2.5 × 10-6 g / 35.45 g mol-1 = 7.05 × 10-8 mol
Hence, concentration = 7.05 × 10-8 mol dm-3
Section reference: 1.5
a. 2.5 × 10–9 mol cm–3
b. 7.1 × 10–11 mol cm–3
c. 1.3 × 10–9 mol cm–3
d. 3.6 × 10–11 mol cm–3
Type: multiple choice question
Title: Chapter 11 Question 03
3) 1.265 g of hydrated magnesium nitrate, Mg(NO3)2.6H2O were dissolved in 100.0 cm3 of water. 10.0 cm3 of this solution were made up with water to 250.0 cm3. Calculate the concentration of Mg2+ ions in the resulting solution.
Section reference: 1.5
a. 0.01973 mol dm–3
b. 0.03411 mol dm–3
c. 0.04933 mol dm–3
d. 0.08528 mol dm–3
Type: multiple choice question
Title: Chapter 11 Question 04
4) A pH-sensitive electrode was calibrated using a series of aqueous standard solutions and the following data for the potential difference for different H+ ion concentrations was obtained. By plotting a calibration graph, determine the H+ concentration of a solution for which the measured potential difference was 0.761 V.
[H+] / 10–3 mol dm–3 | 1.01 | 1.99 | 3.02 | 4.02 | 5.01 |
V / V | 0.768 | 0.750 | 0.739 | 0.732 | 0.726 |
Section reference: 12.2
a. 1.39 × 10–3 mol dm–3
b. 1.78 × 10–3 mol dm–3
c. 1.09 × 10–3 mol dm–3
d. 1.29 × 10–3 mol dm–3
Type: multiple choice question
Title: Chapter 11 Question 05
5) A sample of acetamide is added to a mixture of water and octanol at a temperature of 298 K. If the equilibrium concentration of acetamide in the aqueous layer is 65 mmol dm–3, what is the concentration of the organic layer? The value of the coefficient for the partition of acetamide between octanol and water at this temperature is, expressed as a logarithm, log10K = –1.16.
Section reference: 11.2
a. 4.5 mmol dm–3
b. 75 mmol dm–3
c. 56 mmol dm–3
d. 207 mmol dm–3
Type: multiple choice question
Title: Chapter 11 Question 06
6) In the analysis of the products of a synthesis using thin layer chromatography, spots were observed to have risen distances of 21, 34, 38, and 41 mm up the silica-coated plate, with the solvent front rising to 55 mm. In an analysis of one of the starting materials using the same solvent and type of plate, the spot for the pure compound was observed to rise through 38 mm with the solvent front rising through 62 mm. Which of the spots from the product mixture corresponds to the starting material?
Section reference: 11.3
a. 21 mm
b. 34 mm
c. 38 mm
d. 41 mm
Type: multiple choice question
Title: Chapter 11 Question 07
7) Propane has a retention time of 4.1 minutes and ethane has a retention time of 2.1 minutes in a particular gas chromatogram. Determine the relative retention of propane to ethane.
Section reference: 11.3
a. 1.95
b. 0.51
c. 4.10
d. 0.24
Type: multiple choice question
Title: Chapter 11 Question 08
8) The molar absorption coefficient for solutions of [Cu(NH3)4]2+(aq) ions, is 50 mol–1 dm3 cm–1 at a wavelength of 600 nm. Determine the fraction of light of this wavelength transmitted through a sample of a solution of concentration 0.058 mol dm–3 in a cuvette with a path length of 1.00 cm.
Section reference: 11.3
a. 5.5%
b. 2.9%
c. 7.7%
d. 0.13%
Type: multiple choice question
Title: Chapter 11 Question 09
9) The absorbance of a solution of the amino acid tryptophan, C11H12N2O2, of concentration 1.05 g dm–3 in a cuvette with a path length of 1.0 cm is 10.29 at a wavelength of 240 nm. Determine the molar absorption coefficient at this wavelength.
Section reference: 11.3
a. 5.14 × 103 dm3 mol–1 cm–1
b. 52.9 × 10–3 dm3 mol–1 cm–1
c. 2.00 × 103 dm3 mol–1 cm–1
d. 9.8 dm3 mol–1 cm–1
Type: multiple choice question
Title: Chapter 11 Question 10
10) Flame photometric analysis of a sample of blood plasma resulted in emission at wavelengths of 589 nm and 760 nm. Which metal ions are present in the sample?
Section reference: 11.9
a. Fe2+, Mg2+
b. Na+, K+
c. Na+, Ca2+
d. Fe2+, K+
Type: multiple choice question
Title: Chapter 11 Question 11
11) In order to test the suitability of a solvent for extraction purposes, 1.250 g of solute with molar mass 132.1 g/mol was dissolved in 10.00 mL of water. 5.00 mL of toluene was added, and the system allowed to equilibrate. After extraction 0.925 g of solute is recovered in the organic phase. What is the partition coefficient between water and toluene (expressed as a log K)?
Section reference: 11.3
a. log K = −1.76
b. log K = 5.69
c. log K = 1.32
d. log K = −0.76
Type: multiple choice question
Title: Chapter 11 Question 12
12) Thin layer chromatography is used to measure a reaction progress. Before the reaction begins, the starting materials are observed to rise 24 mm, 31 mm and 39 mm on a plate where the solvent front moves 59 mm. Some reaction mixture is analysed after 1 hour, and three spots are again observed, at 27 mm, 35 mm and 44 mm, on a plate where the solvent front moves 66 mm. What could be deduced from these observations?
Section reference: 11.3
a. No reaction has occurred.
b. On the second plate, the spot at 35 mm represents a reactant.
c. The reaction has proceeded with one of the reactants in excess.
d. On the second plate, the spot at 44 mm represents a reactant.
Type: multiple choice question
Title: Chapter 11 Question 13
13) In order to select a column for routine gas chromatography analysis of two compounds A and B, several columns are tried. The retention times (in seconds) for each of the columns are given. Which column would you select?
Section reference: 11.3
a. Column 1: A: 16 seconds, B 19 seconds.
b. Column 2: A: 39 seconds, B 54 seconds.
c. Column 3: A: 99 seconds, B 134 seconds.
d. Column 4: A: 34 seconds, B 62 seconds.
Type: multiple choice question
Title: Chapter 11 Question 14
14) The absorbance at a particular wavelength was measured for different concentrations of a solution of compound A in a 1.00 cm cell, as shown below. Using a Beer-Lambert plot, determine the molar absorption coefficient.
[A] / 10–5 mol dm–3 | 1.00 | 2.00 | 2.50 | 3.00 | 5.00 |
Absorbance | 0.1230 | 0.2450 | 0.3190 | 0.3860 | 0.6130 |
Section reference: 11.4
a. 350 m2 mol−1
b. 1229 m2 mol−1
c. 8.0 × 10−6 m2 mol−1
d. 1225 m2 mol−1
Type: multiple choice question
Title: Chapter 11 Question 15
15) A Beer-Lambert analysis showed the extinction coefficient for compound B in water to be 345 m2 mol−1 at 450 nm. A different solution of compound B is analysed by UV/visible spectroscopy and the absorbance at 450 nm is recorded as 0.28 in a 1.00 cm cell. What is the concentration of this solution?
Section reference: 11.4
a. 8.1 × 10−4 mol dm-3
b. 1.2 mmol dm-3
c. 12 mol dm-3
d. 8.1 μmol dm-3
Type: multiple choice question
Title: Chapter 11 Question 16
16) Two peaks in a particular gas chromatogram have a retention ratio of 1.25. If this mixture was injected into a gas chromatograph column which had the same stationary phase but a longer column, how would you expect the retention ratio to change?
Section reference: 11.3
a. It would get larger
b. It would get smaller
c. It wouldn’t change much
d. It is not possible to predict
Type: multiple choice question
Title: Chapter 11 Question 17
17) A sample of diethyl ether is added to a mixture of water and octanol at a temperature of 293 K. If the equilibrium concentration of diethyl ether in the aqueous layer is 21 mmol dm–3, what is the concentration of the organic layer? The value of the coefficient for the partition of diethyl ether between octanol and water at this temperature is, expressed as a logarithm, log10K = 0.83.
Section reference: 11.3
a. 3.1 mmol dm−3
b. 2.1 mol dm−3
c. 1.8 mmol dm−3
d. 0.14 mol dm−3
Type: multiple choice question
Title: Chapter 11 Question 18
18) Determine the relative retention time for the two enantiomers shown in Box 11.5
Section reference: 11.3
a. 0.60
b. 4.80
c. 1.66
d. 2.89
Type: multiple choice question
Title: Chapter 11 Question 19
19) The molar absorption coefficient for solutions of guanosine is 8400 mol–1 dm3 cm–1 at a wavelength of 275 nm. Determine the fraction of light of this wavelength transmitted through a sample of a solution of concentration 25 μmol dm–3 in a cuvette with a path length of 1.00 cm.
Section reference: 11.3
a. 7.8 %
b. 62 %
c. 11.2 %
d. 1.6 %
Type: multiple choice question
Title: Chapter 11 Question 20
20) The concentration of chloride ions in a water sample is 250 ppm. Calculate this concentration in mol dm−3.
Section reference: 1.5
a. 8.9 M
b. 7.1 mM
c. 4.2 mM
d. 1.4 M
Type: multiple choice question
Title: Chapter 11 Question 21
21) A standard solution of potassium chloride of concentration 12.5 mg dm−3 was diluted to prepare the solutions shown. Each solution was injected into an atomic emission spectrometer and the emission intensity as shown in the table.
[K+] / mg dm–3 | 2.50 | 5.00 | 7.50 | 10.0 | 12.5 |
Emission intensity / arbitrary units | 131 | 263 | 394 | 525 | 656 |
Draw a calibration plot and determine the concentration of an unknown solution, which was prepared by diluting 10.0 cm3 into 1.00 dm3 of water, and which gave an emission intensity of 315.
Section reference: 11.5
a. 600 ppm
b. 167 ppm
c. 610 ppb
d. 320 ppm
Type: multiple choice question
Title: Chapter 11 Question 22
22) The pH of water at 298 K and 1 atm pressure is 7.0. The pH of water
was measured under these conditions by salespersons for several
commercial pH meters. Which pH meter would you buy?
Section reference: 11.1
a. Meter 1: pH = 7 ± 1
b. Meter 2: pH = 6.90 ± 0.01
c. Meter 3: pH = 7.002 ± 0.004
d. Meter 4: pH = 6.9998 ± 1.0217
Type: multiple choice question
Title: Chapter 11 Question 23
23) The pF of a sample is recorded as 3.5. What is the fluoride ion concentration?
Section reference: 11.2
a. 6.0 ppm
b. 3.5 ppm
c. 16.6 ppm
d. 1.6 ppm
Type: multiple choice question
Title: Chapter 11 Question 24
24) The relative retention for two compounds A and B is quoted as 2.5. From this we can conclude:
Section reference: 11.3
a. A will elute from the column first
b. B will elute from the column first
c. A and B will elute from the column at the same time
d. We need more information to draw a conclusion