2. A set of acidic compounds (pKa between 4 and 5) are to be separated by HPLC. Describethree different ways to separate these compounds. Be specific about stationary phase andmobile phase types employed.

Separating acidic compounds with close pKa values (4-5) using HPLC requires careful selection of…

Answered: 2. A set of acidic compounds (pKa…

Appl Of Ms Excel In Analytical Chemistry

2nd Edition

ISBN:9781285686691

Author:Crouch

Publisher:Crouch

Chapter5: Equilibrium, Activity And Solving Equations

Section: Chapter Questions

Problem 10P

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In a different situation, you want to use acid-base extraction to separate compound A = 5.9) from compound B (pK, = 12.5). You can add either a solution of NaOH or (pK. Na,CO, to act as your aqueous layer. You may look up any relevant pk, values. %3D %3D Which solution should you choose and why would the other one not work?
Can you help me to support this? Based on your observations of your TLC plate and FeCl3 tests, how pure is your aspirin?
Please give me correct solution.
Suppose your colleague was relying on receiving your purified product in order to prepare a dilute aqueous standard solution of benzoic acid e.g. for a titration. She takes 160 mg of your benzoic acid and dissolves it in just enough water so the solution exactly fills a 250 mL volumetric flask. Given that the acid dissociation constant of benzoic acid Ka = 6.3 x 10-5, calculate the pH of her resulting solution.
I was just wondering how you got the 4.0 x 10-4 for the acidionzation constant.
8. Liquid-liquid extraction. A progressive (thought) exercise. a) Benzoic acid, C 6 H 5 CO 2 H, 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…
How is using thiamine as a catalyst rather than cyanide an application of greenchemistry? PROCEDURETo a six inch test tube was added thiamine hydrochloride (0.65 g), followed by water (2mL). The mixture was gently shaken until homogeneous, and then ethanol (7.5 mL)was added. Finally, sodium hydroxide (10%, 1.5 mL) was added and the mixture wasgently stirred to ensure complete mixing.Benzaldehyde (3.8 mL) was then added at room temperature in one portion with gentlestirring. The pH of the resulting reaction mixture was determined and adjusted to >10by dropwise addition of 10% sodium hydroxide. The reaction mixture was then partiallysubmerged in a 65 °C water bath2 and the progress of the reaction was periodicallymonitored by TLC analysis.Once TLC analysis indicated that the reaction was complete, the reaction mixture wascooled to approximately room temperature, and then chilled in an ice-water bath. Theresulting precipitate was collected by vacuum filtration and air-dried. The…
2. Digoxin was solubilised in ethanol. What is the solubility of Digoxin (pKa 7.3) at pH 3, if the solubility of the non-dissociated form is 1 x 107 mol dm¹-³. 3. What is the solubility of Phenobarbital (pka 7.3) at pH 5, if the solubility of the non- dissociated form is 1 x 106 mol dm³.
Propofol (Diprivan) is a very common short-term anesthetic and sedative, and its structure is shown to the right. OH The mass spectrum of propofol is given below. Label the molecular ion peak on the spectrum and suggest a structure for the ion responsible for the 163 m/z base peak. pts) Rel. Intensity 100 80 60 40 20 0.0 0.0 40 litla gula dala 80 m/z 120 160 200 propofol
2. Predict the solubilities, either organic or aqueous, mixture of ethyl acetate and water (pH 7). What molecular characteristic cause dye to be soluble in water? What molecular characteristic causes a dye to be soluble in an organic solvent? Further, predict whether Dyes A, B or C will alter their sol- ubilities if the aqueous phase is changed to an acidic solution (pH 0) or to a basic solution (pH 14). DYE A FO OH OH "Na DYE B SO₂- 'OH *Na 3 SO₂ *Na H₂N DYE C +NH₂ "CI NH₂ 2 h limidlignid
You prepare a buffer solution from 10.0 mL of 0.100 M (3-morpholinopropane-1-sulfonic acid) and 10.0 mL MOPS of 0.089 M NaOH. Next, you add 1.00 mL of 6.13 x 10-5 M lidocaine to this mixture. Denoting lidocaine as L, calculate the fraction of lidocaine present in the form LH+. .545 fraction as LH+ = Incorrect MOPS K₁ = 6.3 x 10-8 CH3 NH arc CH3 Lidocaine Kb = 8.7 x 10-7
Each solution began with a different [Ag+]0. Should the Ksp value be the same for each solution? Explain?

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2. A set of acidic compounds (pKa between 4 and 5) are to be separated by HPLC. Describe three different ways to separate these compounds. Be specific about stationary phase and mobile phase types employed.