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%

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%

Macroscale and Microscale Organic Experiments

7th Edition

ISBN:9781305577190

Author:Kenneth L. Williamson, Katherine M. Masters

Publisher:Kenneth L. Williamson, Katherine M. Masters

Chapter7: Extraction

Section: Chapter Questions

Problem 1Q

See similar textbooks

Similar questions

You are given a substance that is qually soluble in water and hexane (two immisible solvents) a) what is Kd B) if you start with 10g of the substance dissolved in 100ml of water and are given 100ml of hexane to extract with, algebriaically show that it is better to do two smaller extractions using 50 ml of hexane for each extraction than it is to do one extraction using 100ml of hexane
Although other solvents are available, dichloromethane(CH₂Cl₂) is still often used to “decaffeinate” drinks because thesolubility of caffeine in CH₂Cl₂ is 8.35 times that in water.(a) A 100.0-mL sample of cola containing 10.0 mg of caffeine is extracted with 60.0 mL of CH₂Cl₂. What mass of caffeine re-mains in the aqueous phase? (b) A second identical cola sampleis extracted with two successive 30.0-mL portions of CH₂Cl₂.What mass of caffeine remains in the aqueous phase after each extraction? (c) Which approach extracts more caffeine?
Hexanoic acid was added to an immiscible biphasic solvent system, water and CCl4 at 20.0OC and the equilibrium concentrations of hexanoic acid were determined to be 3.66 g/L in H2O and 67.0 g/L in CCl4. Caluclate the distrubution coeffiecent (D2) of hexanoic acid in water with respect to CCl4.
A 25.00 mL sample of an aqueous solution Y is extracted with 50.00 mL of hexane. After extraction, it was found that 94.12% of solute Y was successfully removed from the aqueous solution. Calculate: i. The distribution constant for this separation The initial concentration of Y if 1.77 mmol Y remains in aqueous solution after extraction. iii. The concentration of Y in BOTH phases after extraction
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.
(1a) Pure benzophenane freezes at 66.6 °C. A solution of 7.75 g of biphenyl (C12H10; molar mass = 154.2g/mol) plus 200.08 g of benzophenane froze at 59.9 °C. Calculate the Kf of benzophenane in °C*kg/mol. (b) An unknown solution with possible cations (Ag+, Hg22+, Pb2+) is treated with 6M HCl and a white precipitate forms. Hot water is added to the precipitate, and a white solid remains after filtration. The white solid is treated with aqueous NH3, and the precipitate turns grey or black. The resulting solution is treated with HNO3 and no precipitate forms. What cations can you determine to be present, absent or maybe present? Explain your reason
If the solubility of a compound A in ether is 30g/100 ml, and the solubility of A in water is 15 g /100 ml. a) If 100 ml of aqueous solution of 3g of A are extracted twice with 100 ml ether. How much A total is extracted? b) How much A would be extracted if only one extraction, but with a volume of 200 ml of ether were extracted? c) What is your conclusion from the amount of A extracted in problems a and b above?
The standard addition method is used to analyze a sample of a river water for mercury. Solution A is made by pipetting 5.00 mL of undiluted sample in to a 10 mL volumetric flask and filling to the mark with DI water. Solution B is made by pipetting 5.00 mL of undiluted sample and 3.00 mL of 15.0 ppb of Hg standard into same 10.0 mL volumetric flask and filling to the mark with DI. Solution A and B are analyzed using atomic absorption spectroscopy and give a percent transmittance values of 56 % and 33 % respectively (not blank corrected). A blank has a transmittance of 96%. What is the corrected absorbance of both solution A and B? A. Solution A: 0.123 Solution B: 0.463 B. Solution A: 0.463 Solution B: 0.234 C. Solution A: 0.123 Solution B: 0.234 D. Solution A: 0.234 Solution B: 0.463
1) How many milliliters of 70% ethanol and 20% ethanol must be mixed to prepare 500ml of 30% ethanol? 2) A gaseous blend of nitric oxide and nitrogen (NOmax) contains 0.09% v/v nitric oxide (NO) and 99.92% v/v nitrogen. Express the strength of nitric oxide in PPM (round to whole number) 3) The ratio strength of a 10mL vial of neostigmine methylsulfate injection USP is 1:1500.Calculate the amount of neostigmine methylsulfate in milligrams contained in the 10mL vial. (Round to the whole number).
A empty evaporating dish weighs 30.56g. You place 20.0mL of an NaCl solution in the dish plus the solution weighs 53.31g. You evaporatorate the solution to dryness ant find that the evaporatoring dish plus the residue weighs 32.25g. What is the w/v%? What is the w/w%? What is the molarity?
A 25 mL liquid bleach sample is diluted with water to 1000 mL in a bubble gel. 25 mL of the diluted sample is transferred to the flask with a pipette, excess KI is added to it, and thus OCl- ion turns into Cl- ion and I2 is formed. The released iodine is titrated with 0.09892 M Na2S2O3 using the starch reagent, and 8.96 mL is required for the endpoint. Find the % NaOCl (w/v; w/v) in the bleach sample. (Na=23 g/mol, O= 16 g/mol, Cl = 35.44 g/mol) (Warning: solving the necessary reaction equations by writing is necessary to see the stoichiometric relationship) A. 0.132% B. 0.264% C. 5.28% D. 10.56%
the following data were the results from six replicate determinations of iron in aqueous samples of a standard solution containing 20ppm iron (III) 19.8, 19.6, 19.5 ,19.4, 20.1, 20.3 DETERMINE THE MEDIAN FOR THE DATA