Question 5 Which chemical will be used to separate the benzoic acid from the other components? O Water O Isopropyl alcohol O Silicon dioxide O Not listed 10 pts
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It is soluble in water but not very soluble in non-polar solvents. Show more…
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Sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4) are two drying agents which are commonly used in the lab, especially in extraction: A) Describe briefly, with chemical equations, how the drying agents work. B) How will you judge if the amount of drying agent is sufficient and that the solution is dry? Based on the data provided in the following table, describe an extraction method to separate a mixture containing equal amounts of phenol and benzoic acid. Fill out information in the flow chart of the extraction method shown below: Acid pKa Conjugate base HC≡CH 25 HC≡C- C6H5-COOH (Benzoic acid) 5 CH3CONH- CH3CH2SH 10.6 CH3CH2S- C6H5-OH (Phenol) 12 NO2-C6H4-O- CH3COOH 4.8 CH3COO- A) Extraction description: B) Flow chart of the separation (fill out proper reagents in boxes) phenol and Benzoic acid in ether Ether Layer Aqueous Layer
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8. Liquid-liquid extraction. A progressive (thought) exercise. a) Benzoic acid, C6H5CO2H, is insoluble in water (< 1 w/w %). A suspension of solid benzoic acid in water is treated with enough 1.0 M NaOH (aq) to react with the acid. What balanced acid-base reaction takes place? b) Judging by the products in this reaction, do you expect the benzoic acid to dissolve in the resulting aqueous phase? yes, or no, and why c) Now, make a biphasic mixture of diethyl ether and water (see #7, above). Use a separatory funnel, as in the illustration above. Which substance is the upper layer? ______________ d) Add solid benzoic acid to these layered solvents, and mix thoroughly. Does the benzoic acid dissolve, and if so, where should it be found? ____________________ e) Then, make the pH of the aqueous phase alkaline (basic) with NaOH until the pH = 11.00. Again, mix thoroughly. Where should the benzoic acid be found now? ____________________ f) Separate the two phases carefully, placing them in separate beakers. Label them: ether phase; aqueous phase. To the aqueous phase, carefully add HCl(aq) until pH = 2.00. What happens? Write the balanced acid-base reaction that takes place. g) How may solid benzoic acid (precipitate) be separated from the acidic aqueous solution? (method or technique)
A student inadvertently mixed benzyl alcohol with benzyl amine and chooses to separate them by extraction. The steps to separate these compounds are given below. Match the blank with the proper reagent (You may use any option more than once, and there is only one right combination). • Fully dissolve the mixture in 1____. Next, add 2____ to form a bilayer that mostly separates the two compounds into different layers, and then perform an extraction. After drying the extracts with anhydrous sodium sulfate, the extraction solvent is evaporated carefully to leave 3____. Neutralize the remaining aqueous layer by adding enough 4____, and extract with 5____. After drying the extracts with sodium sulfate, the organic solvent is evaporated to leave 6____. Numbered Blank 22. blank 1 23. blank 2 24. blank 3 25. blank 4 26. blank 5 27. blank 6 Reagent A. acetone B. benzyl alcohol C. benzyl amine D. dichloromethane E. ethanol F. HCL (6 N) G. NaOH (6 N) H. water
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