Exam 1
Name __________________________
CHEM 210
1. (4 pts) Assign all non-zero formal charges to the appropriate atoms in each of the following molecules. All lone pairs
have been drawn in. Be sure to use circled charges!
a.
b.
b.
c.
d.
2. (4 pts) What is the hybridization of the following atoms?
a.
b.
b.
c.
d.
3. (9 pts) Draw one valid Lewis structure for each compound. Assign formal charges to atoms if necessary.
a.
H 2O 2
b. H6BN
c. CH4N
4. (9 pts) Consider 1-hydroxybut-3-yn-2-one
nd
Predict all bond angles between 2 row elements in the following compound
(redraw the compound for clarity):
Draw a structural isomer of this
compound:
What is the approximate length of the C≡C bond?_____Å Of the O—H bond ______Å? Of the C—OH bond ______Å?
5. (8 pts) Name the following functional groups:
a. (CH3)3N
b.
CH
b. 3SH
c.
d.
6. (8 pts) In each row (a.-d.), which compound is the strongest Bronsted-Lowry acid? (Circle the correct answer)
a.
NH3
H 2O
H 2S
CH4
BH3
b.
c.
d.
NH3
7. (2 pts) Which of the following species is the strongest base?
A. CH3
B. H
C. Cl
8. (2 pts) Which halide is the strongest base?
A. I
B. Br
D. HO
C. Cl
E. F
D. F
9. (5 pts) Complete the following chart providing the missing condensed or skeletal structure:
a.
b.
c.
Condensed
(CH3)3COCCCH3
HOCH2CH(CH3)CHO
structure
Skeletal
structure
10. (10 pts) Consider nicotine:
a. What type of orbital does the lone pair on the nitrogen in the 6-membered ring reside? _____
b. What type of orbital does the lone pair on the nitrogen in the 5-membered ring reside? _____
c. Overall do you expect nicotine to be a Lewis base or Lewis acid? _____________________
d. Do you expect nicotine to be water soluble? _____________
e. What is the strongest intermolecular force exhibited by this molecule? ___________________
f. How many total hydrogen atoms are there in nicotine? _______
11. (8 pts) Draw all contributing resonance structures for each molecule:
a.
b.
12. (6 pts) What are the products for the following acid-base reaction?
What is the pKA of the alkyne on the right side of the equation? ________
What is the pKA of alkene on the left side of the equation? ________
Which side of the equation does the equilibrium lie? __________
+
13. (6 pts) What are the products for the following acid-base reaction? The pKA for an ammonium ion (NH4 ) is 9 for
reference.
What is the pKA of the hydrochloric acid on the left side of the equation? ________
Which side of the equation does the equilibrium lie? __________
14. (7 pts) Which is the stronger acid, cylcohexanol or phenol? Briefly describe why (use of equations is strongly advised
to support your argument!)
OH
OH
cyclohexanol
phenol
15. (5 pts) Consider the following Lewis acid-base reaction
a. Provide the products of the following reaction (Draw in all lone pairs and formal charges!)
b. Use curved arrows formalism to show electron movement
c. Label and classify the acid and base (as Lewis or Bronstead)
d. Label the nucleophile and electrophile
16. (7 pts) Carbene is a reactive carbon species. The structure is shown at right, including all atoms and lone
pairs of electrons. What is the hybridization of the carbon atom? What is its formal charge? Draw an
illustration of the molecular orbitals that constitute this molecule and be sure to indicate which orbital the
lone pair of electrons is located, and to label the types of orbitals involved:
H C
H
carbene
SCORE ____________/100
Exam 1
Name KEY
CHEM 210
1. (4 pts) Assign all non-zero formal charges to the appropriate atoms in each of the following molecules. All lone pairs
have been drawn in. Be sure to use circled charges!
a.
b.
b.
c.
d.
2. (4 pts) What is the hybridization of the following atoms?
a.
b.
b.
sp
c.
d.
sp2
sp2
sp3
3. (9 pts) Draw one valid Lewis structure for each compound. Assign formal charges to atoms if necessary.
a.
H 2O 2
b. H6BN
c. CH4N
Question not graded –
+ charge missing on exam
Was supposed to be:
4. (9 pts) Consider 1-hydroxybut-3-yn-2-one
nd
Predict all bond angles between 2 row elements in the following compound
(redraw the compound for clarity):
Draw a structural isomer of this
compound:
Many answers, example:
What is the approximate length of the C≡C bond? 1.2-1.3 Å Of the O—H bond 1.0 Å? Of the C—OH bond 1.4-1.5 Å?
5. (8 pts) Name the following functional groups:
a.# (CH3)3N#
b.#
CH
b.#3SH##
Amine#
Thiol#
c.#
d.#
Ester#
#
#
aldehyde#
6. (8 pts) In each row (a.-d.), which compound is the strongest Bronsted-Lowry acid? (Circle the correct answer)
a.
H 2S
b.
c.
d.
7. (2 pts) Which of the following species is the strongest base?
A. CH3
8. (2 pts) Which halide is the strongest base?
D. F
9. (5 pts) Complete the following chart providing the missing condensed or skeletal structure:
a.
b.
c.
Condensed
(CH3)3COCCCH3
HOCH2CH(CH3)CHO
structure
(CH3)2CHOH
Skeletal
structure
10. (10 pts) Consider nicotine:
2
a. What type of orbital does the lone pair on the nitrogen in the 6-membered ring reside? sp
3
b. What type of orbital does the lone pair on the nitrogen in the 5-membered ring reside? sp
c. Overall do you expect nicotine to be a Lewis base or Lewis acid? Lewis base – e pair donor
d. Do you expect nicotine to be water soluble? Falls on borderline, both answers correct
e. What is the strongest intermolecular force exhibited by this molecule? Dipole-dipole
f. How many total hydrogen atoms are there in nicotine? 14
11. (8 pts) Draw all contributing resonance structures for each molecule:
a.
b.
12. (6 pts) What are the products for the following acid-base reaction?
What is the pKA of the alkyne on the right side of the equation? 25-30
What is the pKA of alkene on the left side of the equation? 40
Which side of the equation does the equilibrium lie? Left
+
13. (6 pts) What are the products for the following acid-base reaction? The pKA for an ammonium ion (NH4 ) is 9 for
reference.
What is the pKA of the hydrochloric acid on the left side of the equation? -10
Which side of the equation does the equilibrium lie? right
14. (7 pts) Which is the stronger acid, cylcohexanol or phenol? Briefly describe why (use of equations is strongly advised
to support your argument!)
OH
OH
cyclohexanol
phenol
Compare conjugate base stabilities: cyclohexanol localizes all (-) charge on a single oxygen; phenol can delocalize this
charge into the ring by resonance
15. (5 pts) Consider the following Lewis acid-base reaction
a. Provide the products of the following reaction (Draw in all lone pairs and formal charges!)
b. Use curved arrows formalism to show electron movement
c. Label and classify the acid and base (as Lewis or Bronstead)
d. Label the nucleophile and electrophile
Lewis acid/E+
Lewis base/N
16. (7 pts) Carbene is a reactive carbon species. The structure is shown at right, including all atoms and lone
pairs of electrons. What is the hybridization of the carbon atom? What is its formal charge? Draw an
illustration of the molecular orbitals that constitute this molecule and be sure to indicate which orbital the
lone pair of electrons is located, and to label the types of orbitals involved:
H C
H
carbene
Follow rules exactly:
2
Two atom attachements and one lone pair = 3 groups = sp
FC = ½ (4 bonding electrons to hydrogens) + 2 lone pair electrons = 4, carbon is neutral
SCORE ____________/100