CHEMISTRY 150. April 2012

Transcription

1 CHEMISTRY 150 Dr. B. MacLean April 2012 NAME: (please print) ID #: This is a three hour exam. SUGGESTION: Read over the entire exam before beginning, and begin by doing those questions which you find easiest. Ration your time according to the value of each question. There should be 13 pages in this exam (including this page). If your exam copy does not have 13 pages, notify me immediately. Answer all parts of this exam as indicated. For multiple choice questions, use the data card provided and hand this card in with your exam when you are finished. Be sure to indicate your name and ID number on this card and the exam. It is your responsibility to ensure that all of your answers are legible. READ ALL QUESTIONS CAREFULLY Questions Out of Sec A 30 B1 24 B2 10 B3 10 B4 16 B5 or B6 10 TOTAL 100 1

2 Section A: Multiple choice - 30 points (1 each): Answer each of the following multiple choice questions on the computer card provided by shading the letter (a, b, c, or d) that corresponds to the best response in each case. A1) The subatomic particles that are located in the core of an atom are, in general, called a) electrons b) protons c) neutrons d) nucleons A2) A glycoside is an example of a a) acetal b) hemiacetal c) lipid d) phosphate ester A3) Which of these species is positively charged? a) b) c) d) A4) Nylon-6,6 (which I synthesized in class this year) is a a) polyester b) polyamide c) carbohydrate d) hydrocarbon A5) Which of the formulas below corresponds to a free radical? a) H 2 O b) H 3 O + c) OH - d) H 2 O + A6) How many 2 o carbons are contained in the following chemical structure? a) 0 b) 1 c) 2 d) 3 2

3 A7) Which of the following molecules is a heterocyclic amine? e) a b c d A8) What factor determines the order of boiling/melting points for a series of substances? a) intermolecular forces b) intramolecular forces c) water-solubility d) molecular shape A9) An alkene having 6 carbon atoms is a functional group isomer of a) a 6-carbon alkyne b) benzene c) a 6-carbon alkane d) a 6-carbon cycloalkane A10) Which of the following molecules will not undergo oxidation? a) an aldose b) 2-Methylpropanal c) 2-Methy-2-propanol d) Ethanol A11) Which of the following pairs of molecules are diastereomers? a) cyclohexene and 2-hexyne b) (+)-2-butanol and (-)-2-butanol c) cis-2-butene and trans-2-butene d) D-glucose (and aldohexose) and D-fructose (a ketohexose) A12) Enzyme-mediated oxidation of D-glucose will yield a) a sugar alcohol (glucitol) b) an aldaric acid (D-glucaric acid) c) an aldonic acid (D-gluconic acid) d) an alduronic acid (D-glucuronic acid) 3

4 A13) Mercaptans are a) thioethers b) thiols c) thioesters d) aromatic acohols A14) Which of the following reactions is not a condensation reaction? a) esterification b) saponification c) amidification d) glycoside formation A15) Which of the following molecules will turn litmus paper blue in an aqueous solution? a b c d A16) A monosaccharide that possesses three chiral centers will have (up to) diastereomers. a) 3 b) 6 c) 7 d) 8 A17) Intramolecular dehydration of an alcohol will yield a(n) a) alkene b) ether c) alkane d) ester A18) A radionuclide has a half-life of 1 day. After 3 days, 32g of this radionuclide will decompose so that only a) 16g remains b) 8g remains c) 4g remains d) 2g remains A19) Which one of the following reaction types is not possible for triacylglycerols? a) saponification b) hydrogenation c) glycolysis d) oxidation 4

5 A20) The carbon atom that is present in a carbonyl group is a) sp-hybridized b) sp 2 -hybridized c) sp 3 -hybridized d) saturated A21) Which of the following molecules can undergo an elimination reaction? a) butanone b) 1-butene c) acetic acid d) 1-propanol A22) The reaction of an aldehyde with an alcohol will yield: a) a hemiacetal b) a carboxylic acid c) a ketone d) an aldose A23) In benzene, there are -bonds a) 2 b) 3 c) 6 d) none A24) Monocarboxylic acids that possess long carbon chains are called a) unsaturated acids b) keto acids c) fatty acids d) metabolic acids A25) Two organic molecules that have the same atom-to-atom connectivity and differ only in the way that their carboncarbon bonds are rotated are called a) constitutional isomers b) stereoisomers c) skeletal isomers d) conformers A26) Which of the following substances cannot participate in hydrogen bonds with water molecules? a) Ethanol b) Ethane thiol c) Ethanoic acid d) Dimethylether 5

6 A27) A reaction in which H 2 O is added across a C-C double bond is called a a) hydrolysis reaction b) hydrogenation reaction c) hydration reaction d) hydrohalogenation reaction A28) Atoms of the same element that have different mass numbers are called a) isomers b) radionuclides c) isotopes d) nuclides A29) Which of the following molecules is a lactam? e) a b c d A30) Which of the following structures corresponds to a reducing sugar? a b c d 6

7 Section B: Long-answwer problems - 70 points. Answer questions B1-B4 and either of B5 or B6 in the space provided. B1) Complete each of the following chemical reactions, indicating the structures of all organic products in each case. You do not need to indicate major/minor products. [24] a H2O HCl b H2SO4/180 o C c NaOH d H + e Tollens' reagent f H2O H2SO4 g AlCl3 h i H2, catalyst 7

8 B2) Answer each of the following questions: [10] a) In this course, we looked at the effect of intermolecular forces on things like melting/boiling points and watersolubility. In the list of compounds shown below, indicate the type of intermolecular forces that exist for each case (assuming an interaction with another molecule like itself) with a check mark: Compound H-Bonding Dipole-Dipole London forces aromatic aldehyde amine ester b) Arrange the following molecules in terms of their boiling points: hexane, cyclohexane, 3-methylpentane (READ THE ORDERING): (lowest) < < (highest) c) Arrange the following in terms of their boiling points: butanoic acid, butanol, butanamine (READ THE ORDERING): (lowest) ) < ) < ) (highest) d) Arrange the following in terms of increasing water-solubility: a disaccharide, a triacylglycerol, 1-pentanol (READ THE ORDERING): (lowest) ) < ) < ) (highest) 8

9 B3) Complete the following diagram by drawing the kind of isomer indicated in the appropriate field: [10] positional isomer skeletal isomer functional group isomer enantiomer diastereomer 9

10 B4) Provide correct names (IUPAC or common) for each of the following structures or draw structures that correspond to the names provided in the appropriate fields: [16] 1,1,1-tribromo-2-methyl-2-propanol 2,N-dimethylaniline (E)-2,3-dichloro-2-butene Linolenic acid (18:3 9,12,15 ) 10

11 Do either B5 or B6. Each is worth 10 points B5a) Draw a Haworth projection for -D-fructose: D-Fructose b) Draw all organic products for each of the following reactions involving triacylglycerols: oxidation complete hydrolysis b) Write a balanced equation for each of the nuclear decay processes shown: Th-225 ( -decay) tin-126 ( -decay) 11

12 B6a) List three basic differences between chemical reactions and nuclear reactions: i) ii) iii) b) How many (total) stereoisomers exist for ketohexoses? Answer: c) List five functions of carbohydrates in humans: i) ii) iii) iv) v) 12

13 BONUS QUESTION (HOORAY!!): [2] Fun fact: D- glucose is present in sucrose: L-Glucose, which is not naturally occurring, is not metabolized by the body. It would seem to make it a great choice for an artificial sweetener; however, the cost of synthesizing it on a large scale for everyday consumption makes it unsuitable for this use. Draw the Fischer and Haworth projections for L-glucose. 13