10 grams of compound A is dissolved in 50ml water Methanol will be used to extract A form water knowing that the distribution coefficient of compound A between methanol and water is 8 how much of A will be in Methanol if it was extracted from water with three sequential extractions using 30 mL of methanol each time and then combine the methanol extracts Select one O 0051 0 1 95 O 8 03 O 995

10 grams of compound A is dissolved in 50ml water Methanol will be used to extract A form water knowing that the distribution coefficient of compound A between methanol and water is 8 how much of A will be in Methanol if it was extracted from water with three sequential extractions using 30 mL of methanol each time and then combine the methanol extracts Select one O 0051 0 1 95 O 8 03 O 995

EBK A SMALL SCALE APPROACH TO ORGANIC L

4th Edition

ISBN:9781305446021

Author:Lampman

Publisher:Lampman

Chapter88: Column Chromatography

Section: Chapter Questions

Problem 5P

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A 18 g of unknown organic sample was dissolve in 756 mL of benzene. The boiling point of benzene was increased by 3.36oC. As the first step of analysis, determine the moecular weight of the unknow sample? Kb of benzene= 2.64oC/m Bb of benzene = 80.09 oC density of benzene = 0.874 g/mL at 25 °C Answer in whole number, no units required.
A scientist wishes to measure the concentration of methyl benzoate in a plant stream by gas chromatography. He prepares a sample of butyl benzoate to use as an internal standard. The results of a preliminary run, which used a solution known to contain 1.37 mg/mL of methyl benzoate (peak A) and 1.51 mg/mL of butyl benzoate (peak B), are shown. The area of peak A is determined to be 3.40×102 and the area of peak B is determined to be 398 measured in arbitrary units by the computer. To measure the sample, 1.00 mL of a standard sample of butyl benzoate containing 2.49 mg/mL is mixed with 1.00 mL of the plant stream material. Analysis of the mixture gave a peak area of 437 for peak A and 415 for peak B. What is the concentration of methyl benzoate in the plant stream?
Calculate the vapor pressure of propanol (b.p. 97.0 ∘C97.0 ∘C) at the gas chromatography column temperature of 95.0 ∘C95.0 ∘C using the form of the Clausius–Clapeyron equation shown ln(?1?2)=−(Δ?vap?)(1?1−1?2)ln(P1P2)=−(ΔHvapR)(1T1−1T2) where ?R is the ideal gas constant, Δ?vapΔHvap is the enthalpy of vaporization, ?1T1 and ?2T2 are two different temperatures, and ?1P1 and ?2P2 are the vapor pressures at the respective temperatures. The enthalpy of vaporization can be estimated using Trouton's rule, Δ?∘vap=(88 J·mol−1⋅K−1)×?bp.ΔHvap∘=(88 J·mol−1⋅K−1)×Tbp. ?=P= TorrTorr Calculate the vapor pressure of pentane (b.p. 36.0 ∘C36.0 ∘C) at the same column temperature. ?=P= TorrTorr For compounds of the same chemical class, what is the relationship between vapor pressure of a compound and retention in gas chromatography? As the vapor pressure decreases, retention time decreases. As the vapor pressure increases, retention time increases. As…
Louie performed paper chromatography to identify which among the four availablereference mixtures — WAR, OFF, YIN, MEW — have the same components as hisunknown sample, GUN. He spotted the standards and the sample in a Whatman No. 1filter paper, which he placed in a developing chamber containing 3% KCl. After 20minutes, Louie obtained the chromatogram below, immediately noting that the distancetravelled by the solvent from the origin is 79.0 mm. On the other hand, the distances (incm) traveled by the developed spots were tabulated as follows.(see attached) Questions: 1. Is the type of paper chromatography performed normal or reversed? Why?2. Calculate the Rf of the spots from the samples. Report your answers in four decimal places.
2 Suppose a particular extraction proceeds with a distribution coefficient of 7.5. The mixture consists of a certain amount of caffeine dissolved 100 mL of water a. How much caffeine was originally used when 0.31 g of the organic compound was dissolved in water and 150 mL ether was used as extraction solvent b. How much was dissolved in ether?
A brewed tea brand sample was subjected to solvent extraction to extract caffeine. The cup of tea measuring 200 mL was extracted with petroleum ether. With KD = 20.0 (caffeine in pet ether-water), the % caffeine (194.10) extracted after 3 extractions with a total of 75.0 mL pet ether used is: A. 97.7% B. 28.6% C. 71.4% D. 2.33%
Penicillin F is recovered from a dilute aqueous fermentation broth by extraction with amyl acetate, using 6.5 volumes of solvent per 100. volumes of the aqueous phase. At pH = 3.8 the distribution coefficient KD is 74. (a) What fraction of the penicillin would be recovered in a single ideal stage? (b) What would be the recovery with three-stage extraction using fresh solvent in both stages? (c) How many ideal stages would be needed to give the same recovery as in part (b) if a counterflow cascade were used with V/L = 0.065?
3. Assume that in extraction from water into toulene, analyte A has distribution ratio of 10. A 20 mL portion of an aqueous solution of A is extracted with toulene. Which of thw following procedures will result in most efficient removal of A from the aqueous phase into toulene? (Please show the solution of the correct answer) A. 1 extraction with 20 mL of touleneB. 1 extraction with 40 mL of touleneC. 2 extractions with 20 mL of toulene eachD. 4 extractions with 10 mL of toulene each
10g coffee 4g sodium carbonate 40m dichloromethane 160ml distilled water coffee filter What are the principles behind caffeine being extracted from coffee using the above items? 1st sodium carbonate mixed with coffee then brought to a boil for 20min then solution/grinds are filtered. Then solution is added to a separatory funnel with 15ml of dichloromethane and two layers are observed so the bottom layer with DCM contains the caffeine, then this layer is collected in a beaker and dried out using molecular seeds. Then the solvent is brought to a boil with crude caffeine remaining and recystallized using 95% ethanol and brought to a boil again. Then the contents are vaccum filtered and allowed to dry resulting in 30mg caffeine.
In a chromatographic analysis, a solution containing 0.0837M toluene and 0.0666M xylene resulted in peak areas of Atoluene= 423 and Axylene= 347. To analyze an unknown sample, 10.0mL of 0.146M xylene was added to 10.0mL of an unknown toluene-containing solution, and the mixture was diluted to 25.0mL. This mixture gave a chromatogram with peak areas of Atoluene= 553 and Axylene= 582. What was the concentration of toluene in the unknown solution?
Earth, a CHEM 40.1 student, extracted a mixture of pigments from the roots of Rubiatinctorum, commonly known as rose madder. Earth spotted the root extract on twohydrophobic silica gel plates. He then placed each plate in separate developing chambers,one containing solvent system WHITE and the other housing solvent system MIX. Earthallowed the chromatograms to develop for around five minutes. Afterwards, he removedthe plates from the containers and placed them inside an iodine chamber. Thechromatograms resulting from the TLC experiment after visualization are illustrated asfollows. The distances travelled by each spot and by the solvents were measured andrecorded in the displayed table.
Internal standard. When 1.06 mmol of 1-pentanol and 1.53 mmol of 1- exanol were separated by gas chromatography, they gave relative peak areas of 922 and 1 570 units, respectively. When 0.57 mmol of pentanol was added to anunknown containing hexanol, the relative chromatographic peak areas were 843:816 (pentanol:hexanol). How much hexanol did the unknown contain?