A 25 g of butyric acid was extracted with 400 mL ether from 400 mL water (Kd=3.0 at 25 °C) Using single-step extraction, what is the amount of butyric acid in water layer? What is the total amount of butyric acid extracted using two successive extractions? Calculate the % efficiency of two-step extraction over single

A 25 g of butyric acid was extracted with 400 mL ether from 400 mL water (Kd=3.0 at 25 °C) Using single-step extraction, what is the amount of butyric acid in water layer? What is the total amount of butyric acid extracted using two successive extractions? Calculate the % efficiency of two-step extraction over single

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

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1. A sample of an infusion was diluted 10 ml to 250 ml and then 10 ml to 200 ml. It was then analysed and was found to contain sodium at 0.789 mg/100 ml. Calculate the concentration of sodium in the original sample in %w/v. The sample was composed of a mixture of sodium lactate and sodium carbonate in equimolar amounts. Calculate the amount of sodium lactate and sodium carbonate in mg/10 ml of the sample (Na = 23, lactate = 89, carbonate = 60) 2. 0.641 g of a semi-synthetic alkaloid was dissolved in 25 ml of 1% w/v acetic acid and was analysed directly by HPLC. The solution was found to contain 1.42 mg/100 ml of an impurity. What is the level of impurity in % w/w and ppm? 3. Calculate the pH of a buffer system made by dissolving 1.2 g of acetic acid and 0.82 g of sodium acetate in 500 ml of distilled water (pKa of acetic acid = 4.7) 4. Convert the following concentrations into the required expression. Concentration given Expression required 0.5% NaCl molarity 1 mM of KBr…
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.
6.0 mL of cyclohexanol, 8 mL of 85% phosphoric acid, and 10 drops of sulfuric acid are added to a 50-mL round-bottom flask with boiling chips, and the mixture is distilled into an ice-cooled receiver. The distillate is in the form of a colorless bi-phasic mixture. The cyclohexene upper layer is removed from the water layer, and dried over anhydrous calcium chloride. Isolated is cyclohexene as a clear and colorless foul-smelling liquid. Weighing data is given below. Gross mass: 51.24 g Tare mass: 48.04 g Product mass: 3.2g Question: Calculate the theoretical mass of the cyclohexene product, bearing in mind that the cyclohexanol starting material was measured by volume, not by mass (so you must use the density of cyclohexanol to convert milliliters to grams, before calculating the number of moles). Calculate the percent yield of cyclohexene obtained.
You were given a mixture of two miscible solvent A and B that you are tasked to separate. You know that solvent A has a boiling point of 49 oC while solvent B has a boiling point of 174 oC. Which of the listed method would overall be the most efficient? Fractional distillation Recrystallization Solid-liquid extraction Liquid-liquid extraction Simple distillation Acid-Base extraction
4g 5 g 2 g 100 g 49." R Lactic acid Salicylic acid Trichloroacetic acid Flexible collodion qs ad Sig: wart remover. Use as directed. (a) Flexible collodion contains 20% w/w camphor and 30% w/w castor oil. How many grams of each would be contained in 30 g of the mixture? (b) The specific gravity of castor oil is 0.955. How many milliliters of the oil is contained in 30 g of the mixture? (c) If the specific gravity of the mixture is 0.781, what are the percent w/v con- centrations of lactic acid, salicylic acid, and trichloroacetic acid in the mixture?
A researcher wishes to obtain a glycoside (an organic compound) from an aqueous plant extract using the solvent extraction technique. She therefore performs the following steps: Step 1: An aqueous solution (100 mL) containing 7 g of the glycoside was shaken with 50 mL of ethyl acetate. Step 2: The resulting aqueous layer from Step 1 was further shaken with 50 mL of dichloromethane. Given that: KD for the glycoside in ethyl acetate-water = 0.8 KD for the glycoside in dichloromethane-water = 0.9 (i)Calculate the total mass of glycoside extracted. (ii)If the molar mass of the glycoside = 784.3 g/mol, calculate the molar concentration of the glycoside remaining in the aqueous layer after each extraction.
1,4‐Dimethoxybenzene (0.642 g) was dissolved in 2.0 mL acetic acid in a 25 mL Erlenmeyer flask using heat from a hot plate. Once the solid dissolved, 1.0 mL tert‐ butanol was added, and the reaction mixture was cooled in an ice bath. Then 2.0 mL concentrated sulfuric acid was added in 2‐3 drop portions,stirring the mixture after each aliquot. After the addition, the flask was removed from the ice bath and allowed to sit at room temperature for 15 minutes. Then 1.0 mL water was added dropwise to dilute the acid and the reaction mixture was added to 40 mL cold water in a 100 mL beaker. The solid was vacuum filtered and washed with 5 mL cold water, giving 52 g filtrate. The product wasrecrystallized from 4.5 mL methanol, yielding 0.317 g purified 1,4‐di‐tert‐butyl‐2,5‐dimethoxy benzene (27.2% yield). What is the atom economy, e-factor, and effective mass yield?
A tea bag containing 15 grams of tea leaves with 0.7% of caffeine was used in solid-liquid extraction with 200ml of distilled water followed by liquid-liquid extraction using DCM. If 50.0mg of caffeine requires 10 ml of water and 3.0ml of DCM to be dissolved, how much caffeine can be extracted using 70.0ml of DCM? a. 4.8 x 10^-2 b. 5.7 x 10^-2 c. 3.8 x 10^-3 d. 5.8 x 10^-3
PLEASE USE ANOTHER SOLUTION. WRITE ALL THE PROCESS. What is the minimum distribution constant that permits removal of 99% of a solute from 50.0 mL of water with five 10.0-mL extractions with toluene?
What is the minimum distribution constant that permits removal of 99% of a solute from 50.0 mL of water with two 25.0-mL extractions with toluene? five 10.0-mL extractions with toluene?
Q1. Give three criteria for a good recrystallization solvent. Q2. You want to purify 10 grams of benzoic acid that has been contaminated with 0.2 g of salicylic acid. You are given the following data: Solubility in water at 20 °C Solubility at 100 °C (g/10 ml) Compound (g/10 ml) Benzoic Acid 0.029 0.680 Salicylic Acid 0.680 0.029 0.22 6.67 a) What volume of Boiling water is needed to dissolve the 10 g of benzoic acid? (show calculations) b) How much benzoic acid will crystallize after cooling to 20 °C (show calculations) c) Will any salicylic acid crystals form? Why or why not? (show calculations/ reason for answer) d) What is the maximum amount of benzoic acid that could be recovered in the first crop of this recrystallization? (Show calculations) e) How can you prove the purity and identity of the purified Benzoic acid?
The melting temperature of pure acetylsalicylic acid is 135 degrees Celsius. Based on the results of the melting temperature test, what is the percent purity of your sample of aspirin? Part I Synthesis of Aspirin Mass of salicylic acid used (g) 2.029g Volume of acetic anhydride used (mL) 5ml Mass of acetic anhydride used (vol. × 1.08 g/mL) 5.4g Mass of aspirin synthesized (g) 3.256g Part II Melting Temperature Data Melting temperature (°C) 133°C Part III Salicylic Acid Standard Stock Solution Initial mass of salicylic acid (g) 0.210g Moles of salicylic acid (mol) 0.0147 mol Initial molarity of salicylic acid (M) 0.724 M Part III Beer’s Law Data for Salicylic Acid Standard Solutions Trial Concentration (M) Absorbance 1 10 0.301 2 7.5 0.219 3 5.0 0.163 4 2.5 0.074 Best-fit line equation for the salicylic acid standards Test of the Purity of the…