Researchers used gas chromatography to determine the % v/v methyl salicylate in rubbingalcohol [Van Atta, R. E.; Van Atta, R. L. J. Chem. Educ. 1980, 57, 230-231]. A set ofstandard additions was prepared by transferring 20.00 mL of rubbing alcohol to separate 25 -mL volumetric flasks and pipeting 0.00 mL, 0.20 mL, and 0.50 mL of methyl salicylate to theflasks. All three flasks were diluted to volume using isopropanol. Analysis of the three samplesgave peak heights for methyl salicylate of 57.00 mm, 88.5 mm, and 132.5 mm, respectively.Determine the % v/v methyl salicylate in the rubbing alcohol.

### Step 1: Understand the Principle of Standard AdditionsThe standard additions method involves…

Answered: Researchers used gas chromatography to…

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter31: Introduction To Analytical Separations

Section: Chapter Questions

Problem 31.19QAP

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In a reverse-phase separation, a solute was found to have a retention time of 19.6 min, while an unretained peak had a retention time of 1.45 min when the mobile phase was 20/80 v/v% methanol/water. (b) Calculate the k’ for the solute. (c) Calculate the new k’ if the mobile phase is changed to 60/40 methanol/water assuming identical void volume. (d) Calculate a solvent composition that would bring k’ from initial value to a value of 1.20 using tetrahydrofuran/water mobile phase rather than 20/80 v/v % methanol/water.
(c) What is the minimum distribution ratio that permits removal of 99% of a solute from 50.0 mL of water with (i) two 20.0-mL extractions with an organic solvent; (ii) four 10.0-mL extractions with the organic solvent?
2.) A 0.2185g sample of NaCl was assayed using Volhard Method with 50mL 0f 0.0998N AgNO3 and 11.9mL of 0.1350N NH4SCN. Calculate the % NaCl in the sample.
A student researcher performed a chromatographic separation of caffeine and aspartame. The retention time for caffeine, tc, was found to be 209.6 s with a baseline peak width, w., of 14.4 s. The retention time for aspartame, ta, was 260.0 s with a baseline peak width, wa, of 21.2 s. The retention time for the unretained solvent methanol was 49.2 s. Calculate the average plate height, H, in micrometers for this separation, given that it was performed on a 22.1 cm long column. H = um %3D Calculate the resolution, R, for this separation using the widths of the peaks. R = Calculate the resolution if the number of theoretical plates were to increase by a factor of 2. R2N =
If a 20-mL solvent extracts 80% of the analyte in a single extraction, the "total" extraction efficiency after three successive 20-mLs of extraction would be summed to
A student researcher performed a chromatographic separation of caffeine and aspartame. The retention time for caffeine, te, was found to be 200.8 s with a baseline peak width, we, of 16.1 s. The retention time for aspartame, ta, was 258.7 s with a baseline peak width, wa, of 20.6 s. The retention time for the unretained solvent methanol was 44.2 s. Calculate the average plate height, H, in micrometers for this separation, given that it was performed on a 22.1 cm long column. H = Calculate the resolution, R, for this separation using the widths of the peaks. R = 88.2 R₂5N = 3.16 Calculate the resolution if the number of theoretical plates were to increase by a factor of 2.5. 3.533 Incorrect μm
The distribution constant for X between n-hexane and water is 8.9. What volume of n-hexane is required to decrease the concentration of X to 1.00 x 10-4 M if 45.0 mL of 0.0500 MX is extracted with a. 25.0-mL portions? Volume = mL b. 10.0-mL portions? Volume = c. 2.0-mL portions? Volume = = mL mL
If 30.0 mL of water that is 0.0500 M in Q is to be extracted with four 10.0 mL portions ofan immiscible organic solvent, what is the minimum distribution coefficient that allowstransfer of all but 1.00 x 10–4 of the solute to the organic layer.
Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Can(PO)(OH). Trace elements in teeth of archeological specimens provide anthropologists with clues about diet and disease of ancient people. Students at Hamline University measured the trace element strontium in cnamel from extract wisdom teeth by atomic absorption spectroscopy. Solutions were prepared with a constant total volume of 10.0mL. containing 0.750mg dissolved tooth enamel plus variable concentration of added Sr. \table[[Added Sr (ng/mL- ppb), Signal (arbitrary units)], [0, 28.0], [2.50, 34.3], [5.00, 42.8], [7.50, 51.5], [10.00, 58.6]] a) Prepare a graph to find the concentration of Sr in the 10mL sample solution in part per billion = n m L. (2%) b) Find the concentration of Sr in tooth enamel in part per million = μ (3%) 5. Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca(PO)(OH). Trace elements in teeth of archeological specimens provide anthropologists with clues about diet and…
20 aspirin tablets labeled 80mg were dissolved in 100mL of 90% ethanol. A 10mL aliquot was taken and was used for assay. The analyte followed usual process and was treated with 50mL of 0.1000N NaH and was titrated with 35mL 0.1050N H2O4 until the solution achieved completion. Calculate the % content of the total aspirin capsules and the actual label claim
Thin‑layer chromatography (TLC) can be used as a preliminary identification method for many amphetamine‑type stimulants (ATS). Using a 0.25 mm thick silica gel stationary phase and a 98.5:1.5 methanol:concentrated ammonia mobile phase, a spot was observed to have traveled 3.52 cm when the solvent front traveled 8.81 cm. What is the retardation factor (?F)for the compound that composes this spot?
What is the molarity of an unknown HCl solution with a specific gravity of 1.10 and an assay percentage of 18.5 %? (atomic weight: H = 1.00794, Cl = 35.4527) PLS SHOW SOLUTION

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