CUNY Hunter College CHEM 120 Exam 2 S18 KEY (All Answers are Correct)

CHEM 120 Exam 2 Name: , Last First Total of 137 exam points, adjusted to 100 course points. ADJUSTED SCORE: Part I: Multiple Choice (3 points each, 60 pts total, No guessing correction, so answer ALL questions) Note, only questions that are marked as such might have multiple correct answers. Use the following answers for Numbers 1-24 (12 questions) AA: Alkanes AB: Alkenes AC: Alkynes AD: Aromatics AE: Alkyl Halides BA: 1o Alcohols BB: 2o Alcohols BC: 3o Alcohols BD: 1o Amines BE: 2o Amines CA: 3o Amines CB: 4o Ammonium Salts CC: Aldehydes CD: Ketones CE: Hemiacetals DA: Acetals DB: Carboxylic Acids DC: Esters DD: 1o Amides DE: 2o amides EA: 3o Amides EB: Phenols EC: Ethers ED: Thiols EE: Monosulfides EC: Disulfides To answer these questions requires two lines on the Scantron, one for each letter of the answer. For example: 1-2. Which functional group results in the smelliest compounds? The answer is ED: Thiols. Therefore, you would bubble in E on line 1 on the Scantron, and D on line 2. The order matters (answering DE would be wrong, as that would indicate your answer is 2o amide which is wrong), and both lines are graded together as a single question. Answer this question now on lines 1-2 to get credit for this question. 3-4. Which functional group has a carbonyl group attached to both a carbon and to a hydrogen? CC: Aldehyde 5-6. Which functional group is made by the gentle oxidation of a thiol? EC: Disulfides 7-8. Which functional group is the condensation product of a 1o amine and a carboxylic acid? DE: 2o Amides - a new group is added to the amine to become an amide! 9-10. Which functional group is the most acidic? DB: Carboxylic Acids - phenol common wrong answer 11-12. Which functional group undergoes saponification? DC: Esters 13-14. Which functional group give compounds the highest boiling point? DD: 1o Amides 15-16. Which functional groups has a set of carbon-carbon double bonds with unusual stability? AD: Aromatics 17-18. Which functional group promotes more soluble in aq NaOH than in water, but not more solubility in aq NaHCO3? EB: Phenols - carboxylic acid common wrong answer, but they are more soluble in NaHCO3 ; thiol would also be correct, and credit was given to those (who guess this?) 19-20. Reduction of which functional group gives a 1o alcohol? CC: Aldehydes (others we didn't learn) 21-22. Which functional group is most unstable in water? CE: Hemiacetals - I said in lecture you can't put them in a bottle because they are in equilibrium with alcohol and aldehyde/ketone 23-24. Which of these functional groups reacts with acid to form a salt and does not self-hydrogen bond? CA: 3o Amines - I should have seen the simple structures on many exam that would make this easier Part I /60 Part II /39 Part III /3825. The compound on the right would be classified as A) an aromatic amine B) a primary amine C) a secondary amine Good results! D) a tertiary amine E) a quaternary amine H3C H3C CH3 N CH3 H 26. Which of the following is an alternate name for 2-methyl-1-propoxypropane? A) butyl propyl ether B)sec-butyl propyl ether C) isobutyl isopropyl ether D) sec-butyl sec-propyl ether E) isobutyl propyl ether - only 1/2 got this right - WRITE DOWN THE STRUCTURE! 27. Which of the following is the best name for the compound on the right? A) 3,4-dichlorobenzaldehyde B) 4,5-dichlorobenzaldehyde C) 3,4-dichlorophenylaldehyde D) 1,2-dichlorobenzenaldehyde E) 3,4-dichlorobenzenaldehyde 28. Which of the following structures is a hemiacetal derived from an ketone? Str C (B is from aldehyde) 29. For the following reaction, which of the following changes would shift the equilibrium to the right? Mark all that apply. CH3CH=CH2 + H2O D CH3CHOHCH3 + heat A) Using a larger reaction flask B) Decreasing the amount of CH3CHOHCH3 C) Decreasing the amount of CH3CH=CH2 D) Decreasing the amount water E) Increasing the amount of water 30. The best name for the compound on the right is A) 2,4-diethyl-2-methyl-3-pentanol - an equally common answer! CH3 CH2CH3 B) 3,3,5-trimethylheptanol don't rely on how it is written! C) 5-ethyl-3,3-dimethyl-4-hexanol D) 2-ethyl-4,4-dimethyl-3-hexanol E) 3,3,5-trimethyl-4-heptanol H3C C CH CH CH3 CH3CH2 OHO OH 31. Hemiacetals are usually not stable and revert to the alcohol and the aldehyde or ketone they were made from. Which of the following hemiacetals would be the most stable? Compound A (CYCLIC) Cmpd D most common answer, but the aromatic ring is there in the aldehyde and hemiacetal. 32. What bond angles does VSEPR predict for the carbon in formaldehyde (H2C=O)? A) 60o B) 90o C) 109.5o D) 120o E) 180o Did you write down the structure? Part II, Reactions (3 pts each, 39 pts total) For each of the following reactions, enter the necessary reagents above/below the arrow or enter the structure for the starting material or product, whichever is missing from the equation. 33. H 2 Pt (Showing new hydrogens optional) Cl 34. OH Cr(VI)/water Cl OH excess 35. O OH Cr(VI)/no water H excess 36. O Cr(VI)/no water OH excess H2CrO4/water 37. NR Q 34-37 had disappointing results - learn the reactions! H HNaBH4 O For Question 38, give the starting material (reactant) OH H3O+ 38. Probably the most difficult question on the exam; Kudos to those who got it (almost) right. 39. HS CH3 mild oxidation CH3-S-S-CH3 H3O+ 40. Cl NR (A