Deck 2: Polar Covalent Bonds; Acids and Bases

Question 1

Phenylalanine is an amino acid that is essential to human nutrition. The representation below shows the structure of phenylalanine at the pH found in cells. Consider this structure to answer the following question(s). phenylalanine
Refer to instructions. Assign any formal charges to atoms in this representation of phenylalanine.

Answer 1

Question 2

Consider the reaction below to answer the following question.
Refer to instructions. Using the curved arrow formalism, show the flow of electrons for this reaction.

Answer 2

Question 3

What is the formal charge on the nitrogen atom indicated with the arrow in the following compound?

A) 0
B) −1
C) +1
D) −2
E) +2

Answer 3

+1

Question 4

Use the convention δ−/δ+ and the crossed arrow ( ) to show the direction of the expected polarity of the indicated bonds in the following compound(s).
Refer to instructions. A C−O bond in tetrahydrofuran,

Question 5

Phenylalanine is an amino acid that is essential to human nutrition. The representation below shows the structure of phenylalanine at the pH found in cells. Consider this structure to answer the following question(s). phenylalanine
Refer to instructions. The oxygen atom labeled "B" has _____ nonbonding electrons.

Question 6

Refer to the following equation to answer the question(s) below.
Refer to instructions. The strongest Brønsted-Lowry acid in the equation is indicated by letter _____.

A)A
B)B
C)C
D)D

Question 7

Among the following compounds which can function only as a Brønsted-Lowry base? A B C D

A) A
B) B
C) C
D) D

Question 8

Use the convention δ−/δ+ and the crossed arrow ( ) to show the direction of the expected polarity of the indicated bonds in the following compound(s).
Refer to instructions. The C−F bond in fluorobenzene,

Question 9

Consider the species below to answer the following question.BF₃
Fe²⁺
Refer to instructions. Which of the following would be common to all?

A) Lewis acids
B) Lewis bases
C) Lewis acids or bases
D) Neither Lewis acids nor bases

Question 10

Which of the following molecules would exhibit the largest dipole moment?

A) CH₃CH₃
B) CH₃CH₂F
C) CH₃CH₂Cl
D) CH₃CH₂Br

Question 11

Draw two resonance structures for the species below.

Question 12

The following shows an intermediate used in a Grignard synthesis. Which atom will inductively donate electrons in this species?

A) C
B) Br
C) Mg
D) H
E) both b and c

Question 13

Label the acid and base in each reaction below.
Label:

Question 14

Indole is pleasant smelling in highly dilute solutions and has been used in perfumery. Use the structure of indole, below, to answer the following question(s).
Refer to instructions. Indole can function as a Brønsted-Lowry acid in the presence of strong bases. Formulate a reaction, using a generic base (:B−), showing electron flow with arrows, that demonstrates this reactivity of indole.

Question 15

Refer to the following equation to answer the question(s) below.
Refer to instructions. The strongest Brønsted-Lowry base in the equation is indicated by letter _____.

A)A
B)B
C)C
D)D

Question 16

Refer to the following equation to answer the question(s) below.
Refer to instructions. Will this reaction take place as written in the forward direction? Explain.

Question 17

Phenylalanine is an amino acid that is essential to human nutrition. The representation below shows the structure of phenylalanine at the pH found in cells. Consider this structure to answer the following question(s). phenylalanine
Refer to instructions. The oxygen atom labeled "A" has ______ bonding electron pairs.

Question 18

Consider the structure of acetic acid shown below. In the electrostatic potential map of acetic acid, in which of the following bonds would the terminal atom appear as the deepest shade of red?

A) C=O
B) C−H
C) C−C
D) O−H

Question 19

Circle the Lewis bases in the group of compounds below.

Question 20

Explain why phenol has a lower pK_a than ethanol. phenol
ethanol

Question 21

Write an equation for the reaction of the alkaloid ephedrine with a proton, showing the structure of its conjugate base.

Question 22

The visual pigment in animal cells consists of an isomer of retinal linked to the protein opsin, as shown below. Write an alternative resonance form for this species that shows the positive charge situated on the starred carbon instead of the nitrogen atom and include the curved arrows to show the electron flow.

Question 23

Guanidine is a fairly strong amine base that is attached to the amino acid arginine. Draw three resonance forms for the conjugate acid of guanidine. guanidine

Question 24

Which of the following statements is not true regarding resonance structures?

A) All resonance structures must have the same number of electrons
B) All resonance structures must differ in the hybridization of atoms.
C) All resonance structures must have the same arrangement of atoms
D) All resonance structures must be valid Lewis structures

Question 25

In aromatic nitration reactions, nitric acid (HNO₃) is used in conjunction with the stronger acid, sulfuric acid, H₂SO₄, to form an intermediate. Which of the following could be the formula for this intermediate?

A) NO₃−
B) H₃SO₄⁺
C) H₂NO₃⁺
D) HNO₂

Question 26

Draw the conjugate base of each species.

Question 27

Identify the reactants and product in the reaction below as acids or bases and specify whether they are Lewis and/or Brønsted-Lowry.

Question 28

Write an equation for the reaction of boron trifluoride, an important reagent in organic chemistry, with trimethylamine. Represent the movement of electrons with a curved arrow, and show the formal charges on the atoms in the product.

Question 29

The condensed structure for dimethyl ether looks symmetrical. However, dimethyl ether has a dipole moment. Draw a structure that explains this and indicate the expected direction of the molecular dipole moment. dimethyl ether

Question 30

Use the curved arrow method to show the electron movement, and label the acid, base, conjugate acid, and conjugate base.

Question 31

Rank the following in order of decreasing importance as a contributing resonance structure to the molecular structure of acetone, CH₃COCH₃ (more important > less important). A B C

A) A > B > C
B) A > C > B
C) B > A > C
D) C > A > B

Question 32

Which is the strongest base (pK_a values given for conjugate acid)?

A) NH₃ (pK_a = 9.2)
B) CH₃O− (pK_a = 16)
C)
(pK_a = −6.5)
D) CH₃CO₂− (pK_a = 4.7)
E) H− (pK_a = 35)

Question 33

Consider the molecules below to answer the following question.CH₃CH₂NH₂

Refer to instructions. Which of the following is an accurate description of the noncovalent interactions between like molecules?

A) Only 1 exhibits hydrogen bonding.
B) Only 2 exhibits hydrogen bonding.
C) Only 3 exhibits hydrogen bonding.
D) Only 1 and 2 exhibit hydrogen bonding.
E) All of these exhibit hydrogen bonding.

Question 34

Complete this acid-base reaction, and label the acid, base, conjugate base, and conjugate acid.

Question 35

Draw two resonance forms for the cyclopentadienyl radical.

Question 36

Draw a Lewis structure for each of the following.
a)hydroxylammonium ion: ⁺NH₃OH.
b)azide ion: (N₃−)

Question 37

Indole is pleasant smelling in highly dilute solutions and has been used in perfumery. Use the structure of indole, below, to answer the following question(s).
Refer to instructions. Indole can function as a Lewis base in the presence of strong acid. Formulate a reaction, using a generic acid (HA), showing electron flow with arrows, that demonstrates this reactivity of indole.

Question 38

Which of the following molecules has a dipole moment?

A)

B)

C)

D)

Question 39

Of the bonds found in which is the most polar?

A) C−F
B) O−H
C) C−H
D) C−O

Question 40

Consider the molecules below to answer the following question.CH₃CH₂NH₂

The following is the structure of vitamin C. This compound

A) is hydrophilic.
B) exhibits dispersion forces.
C) exhibits hydrogen bonding.
D) would be soluble in water.
E) all of these.

Question 41

Consider the molecules below to answer the following question.CH₃CH₂NH₂

Which of the following exhibits only dispersion forces? A B C D

A) only A
B) only B
C) only C
D) only D
E) all except B