Download Sample Lab Final Exam Questions - Organic Chemistry and more Lab Reports Organic Chemistry in PDF only on Docsity! 1 CHEM 261 SAMPLE LABORATORY EXAMINATION QUESTIONS The difference between the water-solubility of an organic base and its corresponding salt is used in the organic chemistry laboratory to separate a mixture containing an organic base and an organic neutral compound. A mixture containing 0.60g of an unknown organic base and 0.60 g of an unknown neutral organic compound was dissolved in 30 mL of hexane ( B.P.68 o C, d = 0.659 g/mL). The possible unknowns are shown below. Questions A through F (inclusive) address this separation. NH2 OCH3 N H NH C O CH3 CH3CH2CH2 C O NH2 Acetanilide 4-Metoxyaniline Butanamide Diphenylamine M.P. = 113-115 o C M.P. = 62-64 o C M.P. = 114-115 o C M.P. = 66-67 o C A) What would you add to the hexane solution to extract the organic base? Explain using a general chemical equation. B) If you separate the aqueous layer (from part A) and then add 10 M sodium hydroxide solution, a white precipitate will form. i) What is the precipitate? ii) Support your answer with a general chemical equation. 2 C) The white precipitate formed (see question B) should be separated by: i. gravity filtration ii. vacuum filtration using the water aspirator iii. vacuum filtration using the house vacuum iv. distillation v. hot gravity filtration D) Describe, in three steps, the work-up procedure leading to the isolation of the neutral organic compound, after the organic base is removed. i. --------------------------------------------------------------------------------- ii. --------------------------------------------------------------------------------- iii. --------------------------------------------------------------------------------- E) What method of purification would you choose to purify the neutral organic compound? F) Which two methods of identification would you choose to identify the neutral organic unknown? Assume that the pure standards of all compounds listed on (page one) are available. Explain in detail.
