Sample Exam #1 Solutions

Sample Exams are designed to give you an idea of the types of questions you can expect.  Exam numbers may not exactly agree with currently assigned material, so you may need to examine other sample exams to see questions that might be similar to the upcoming exam.  Be aware, that this sample exam does NOT cover some of the material that will be on the upcoming exam.  Use these sample exams to see the types of problems that will be on your exam.  Study your homework and in text questions primarily.

I have made every effort to show correct answers, but there might be an incorrect answer, so if in doubt, you are probably right.  Also, problems that require elaborate structures may NOT have the answer shown.

1. Give the definition of an acid and a base using either the Lowry-Bronsted and Lewis definitions.  Give one example for each.  A Lowry-Bronsted acid is a proton donor and a base is a proton acceptor.  A Lewis acid is an electron pair acceptor and a base is an electron pair donor.

2. Draw three (3) structural isomers for a molecule containing the empirical formula: C3H8O. (Remember that every C has 4 bonds, every O has 2 bonds and every H has one bond.)

CH3CH2C-OH, CH3CH(OH)CH3, and CH3-O-CH2CH3

3. Starting with Cl2 and CH4, show how you would produce CH3Cl. Be sure to include all reaction conditions, including those necessary to initiate the reaction. This type of reaction is a substitution reaction using a ___________________ intermediate. Why is this reaction sequence considered to be a chain reaction?

  1. Cl2 + UV light and heat ---> 2Cl.
  2. Cl. + CH4 ---> HCl + CH3.
  3. CH3. + Cl2 ---> CH3Cl + Cl.
  4. steps (2) and (3) repeat and repeat and repeat.......it is a chain reaction because Cl. gets regenerated each reaction cycle.

4. Draw the four (4) reaction products you would get in #3 above. Name each.

CH3Cl (chloromethane), CH2Cl2 (dichlormethane), CHCl3 (trichloromethane), and CCl4 (carbon tetrachloride)

5. What is an inhibitor? For the halogenation reactions, show why O2 is an inhibitor. What is the formula for the inhibition product which stops this chain reaction.

6. Draw the nine (9) structural isomers of heptane (C7H16). Include only the C-C bonds, you don't need to show every H.

See book, structures will be shown later.

7. Give names for alkanes having the number of carbons shown. Also, give the generic (empirical) formula for each showing the number of C's and H's.

2 : ethane - C2H6

4 : butane - C4H10

9 : nonane - C9H20

10 : decane - C10H22

12 : dodecane - C12H26

20 : icosane - C20H42

8. Define and give an example of:

ionic bond - bond between any charged ion: cation and anion

covalent bond - bond between atoms where electrons are shared, principally between non-metals

dipole - bond between atoms with a difference in electronegativity

van der Waals interaction - intermolecular force between non-charged, and non-polar molecules

free radical - atom or group of atoms containing an odd (unpaired) electron

9. Show a reaction to convert an alkene into an alkane. Include reactants, catalysts, conditions, etc. required. Then give an example, for a 4-carbon alkene, including names.

CH3-CH2-CH=CH2 (or CH3-CH=CH-CH3) ---> CH3-CH2-CH2-CH3
1-butene (or 2-butene) ---> butane [you need something like H2 and Pt, Ni, or Pd catalysts)

10. For the following compound, please indicate each carbon as being either 1o, 2o, 3o, or 4o.

CH3 carbons are 1o, CH2 carbons are 2o, CH carbons are 3o, and the C carbon is 4o

11. Show the structural formula for:

1-iodo-2-methylpropane - I-CH2-CH(CH3)-CH3

3,3-Diethyl-5-isopropyl-4-methyloctane (carbons listed above or below are bonded to that carbon) 

    C
    |
    C C
    | |
C-C-C-C-C-C-C-C
    |   |
    C C-C-C

3,4,4,5-tetramethylheptane 

    C C
    | |
C-C-C-C-C-C-C
      | |
      C C

5-t-butyl-4,6-diethyl-5-isopropyl-2,2,8-trimethylnonane (C2 is an ethyl group and C3 is a propyl group) 

         C
         |
  C    C-C-C
  |      |
C-C-C-C--C--C-C-C-C
  |   |  |  |
  C   C2	 C3 C2

12. For each of the following, give the correct IUPAC name, redrawing the structure, if necessary to present the longest carbon change in straight horizontal. 

C-C-C-C-C-C-C-C-C-C (3,8-diethyldodecane)
    |         |
    C-C-C-C   C-C

(CH3)2CHCH2CH2CH3 (2-methylpentane)

(CH3)2CHC(C2H5)CH2CH2CH3 (3,3-diethyl-2-methylhexane)

(CH3)3CCH2C(CH3)3 (2,2,4,4-tetramethylpentane)

13. You have a priceless radioactive alkane that you accidentally converted into a mono-bromo derivative. You want to convert it back into an alkane. Show how you could do this using the Grignard reaction. Use *R- as your priceless alkane, since you don't need to show the complete structure. Be sure to include all reactants, requirement for anhydrous reagents, structures for intermediate components. Start with *R-Br and end with *R-H.

*R-Br + Mg -- #1 -->*R-Mg-Br -- #2 --> *R-H + Mg(OH)Br

reaction #1 requires dry ether, and reaction #2 requires addition of water (HOH)

EXTRA CREDIT (5 points; solve either A or B, but not both):

(A) Show the Newman projections for n-butane in the Anti, Gauche (2 are possible), and eclipsed positions.

(B) Show the Potential energy plot as you go from Anti to Gauche to Gauche positions for n-butane. Remember, there will be two (2) different eclipsed positions to plot as energy maximums.

See text for these structures