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Chemistry 201 MW 12pm – 1:15pm

Examination #1

July 20th 2016

Name ………………………………………

Bronco ID …………………………………….

Question Score Possible Points

1 ……… (17pts)

2 ……… (28pts)

3 ……… (14pts)

4 …….... (22pts)

5 ……… (19pts)

……………………………………………………………………………….

Total ……… (100pts)

1. Read each question carefully. Make sure you are answering the question which is being asked. Write your

answer clearly and do not use notation such as to show your answer

2. Answer easier questions first, more difficult questions later

3. Ask the instructor for clarification if you are puzzled by the question

4. Show work for credit. Use dimensional analysis by meant of using an appropriate stiochiometry to prove

your solution. Watch for significant figures.

5. Any forms of cheating will be an automatic F

6. The instructor can’t read students’ mind so DO NOT MAKE ANY ASSUMPTIONS

7. GOOD LUCK

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Question I

A. (14pts): Multiple choices - choose one best answer

1. Which one of the following is a true statement?

A) The stronger the acid, the larger is its pKa.

B) The conjugate base of a strong acid is a strong base.

C) Acid-base reactions always favor the formation of the stronger acid and the stronger

base.

D) Strong acids can have negative pKa values.

E) Hydrogen need not be present in the molecular formula of a Bronsted-Lowry acid

2. Which of the following statements about properties of organic compounds is not correct?

A) Most organic compounds are not soluble in water.

B) Most organic compounds do not conduct electricity.

C) Organic compounds have higher melting and boiling points than ionic compounds.

D) Organic compounds have weak intermolecular forces.

3. Which class of hydrocarbons has the general formula CnH2n?

A) alkanes B) alkenes

C) alkynes D) cylcloalkanes

3. Compounds that have the same formula but different molecular structures are called

A. isoelectronic B. isomers

C. isotones D. isotopes

4. Which of the labeled atoms in the following structure are sp2 hybridized?

A) 2 B) 3

C) 4 D) 2 and 3

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5. Which statement below is false concerning nomenclature rules for alkanes?

A. Carbon atoms are numbered starting with the atom farthest from the branching point

B. Each branching group is assigned a number referring to its point of attachment in the parent chain

C. The name of the alkane is written as a single word

D. The parent name is taken from the longest continuous chain of carbon atoms

6. An alkyl group is named for the part of the alkane group that remains after a ________ is removed.

A) C atom B) CH3 group

C) CH2 group D) H atom

7. Which sequence correctly ranks the indicated protons in order of increasing acidity?

A. 1 < 2 < 3 B. 2 < 3 < 1

C. 2 < 1 < 3 D. 1 < 3 < 2-

8. A molecule of NH3 has a ………………….geometry and a molecular dipole moment that is …………

A. tetrahedral, zero

B. bent, nonzero

C. trigonal planar, zero

D. trigonal pyramidal, nonzero

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9. Rank these molecules or compound according to their boiling point, starting from the highest

Heptanes, 3-hexanol, n-hexylamine, 2-pentanol

I II III IV

A. I > II > III > IV B. IV > III > II > I

C. II > III > IV > I D. III > II > IV > I

10. Which of these is the weakest of the intermolecular attractive forces?

A. ion-ion B. dispersion forces

C. dipole-dipole D. covalent bonding

E. hydrogen bond

11. The structure of vitamin C is shown below. Which one of the following statements concerning this structure

is not correct?

A) The molecule contains 2 pi bonds.

B) The molecule contains 1 sp2 hybridized oxygen atom.

C) The molecule contains 3 sp2 hybridized carbon atoms.

D) The molecule can be classified as an aldehyde.

E) The molecule contains more than one hydroxyl group.

12. What functional group(s) is/are present in the following compound?

A) 1o alcohol and ketone B) carboxylic acid

C) ester D) 1o alcohol and aldehyde

E) alcohol

CO2H

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13. What functional group(s) is/are present in the following compound?

A) Ketone and 1o alcohol B) Ether and alcohol

C) Ester and ether D) Ester and 1o alcohol

E) 1o alcohol and aldehyde

B. (4pts) True or False

1. …………..A carbon-carbon double bond is formed by the overlap of sp2 hybrid orbitals, and a triple bond

is formed by the overlap of sp3 hybrid orbitals.

2. ………..All molecules with polar bonds are polar

3. ……….The direction of equilibrium in an acid-base reaction favors the side containing the stronger acid

and stronger base

4. ………..The conjugate acid-base pair differ only by a proton

CO2CH2CH3

OH

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Question II (28pts)

1. (20pts) For the following reaction

a. Predict the products expected for the Bronsted-Lowry acid/base reaction:

b. In the boxes provided, label each of the above products. (e.g., acid, base, conj. acid, conj. base)

c. Use curved arrows to show the reaction mechanism.

d. To which side does the equilibrium lie (R/forward or L/reverse)? Explain in detail to support your answer

2. (8pts) Redraw the following molecule then using curve arrows to show how it make then identify the Lewis

acid and Lewis base

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Question III (14pts)

1. (8pts) Fill in the missing electrons and draw one more resonance this structure, using an arrow to show the

movement of electrons then label the major and minor contributors and state your reason.

3. (6pts) Explain why one of these anions is much more stable than the other

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Question IV(22pts)

1. (8pts) Using bond-line to draw the following molecules

a. (1o) N-isobutyl amine b. 4-tert-butyl-2,3-dimethylheptane

2. (6pts)Name the following molecules

a. d.

2. (8pts) Draw all the isomers with the following formula of C5H11OH. The total number for each is gen

in parentheses. (Use bond-line drawing)

Primary alcohol (1) Secondary alcohol (2) Tertiary alcohol (1)

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Question V: (19pts)

(18pts) Looking down from the indicated direction, draw all Newman projections by rotating around the C2-C3 for the

molecule below and rank them on the energy diagram.

OH is more energetic than an alkyl group

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Bonus: (5pts) Show hydrogen bonding between the following molecules

Methanol and water methylamine and water.

A B

a. Identify H-bond acceptor and H-bond donor

b. Which H-bond is stronger (A or B)? Explain

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