Deck 4: Acids and Bases

Question 1

Which of the following compounds is the strongest acid?

A)CH₄
B)CH₃CH₃
C)H₂C=CH₂
D)HC $\equiv$ CH

Answer 1

HC $\equiv$ CH

Question 2

The pK_a of acetic acid, CH₃COOH, is 4.76. What is the value of the equilibrium constant K_eq, for the following equilibrium? [The concentration of water in a dilute aqueous solution is 55 M]

A)"3.2 * 10⁷"
B)"-3.2 * 10^-7"
C)"-3.2 * 10⁷"
D)"3.2 *10^-7"

Answer 2

"3.2 *10^-7"

Question 3

Which of the following is the strongest acid?

A)CH₃OH
B)CH₃CHO
C)CH₃COCH₃
D)CH₃COOH

Answer 3

CH₃COOH

Question 4

Which of the following is the correct order of decreasing basicity (stronger base > weaker base)?

A)NH₃ > MeNH₂ > H₂O > HF
B)MeNH₂ > NH₃ > MeOH > CH₄
C)NH₃ > Me₃N > H₂O > MeOH
D)CH₃COONa > NaOH > NaOMe > NaNMe₂

Question 5

The pK_a of HCl is -7. What is the value of the equilibrium constant, K_eq, for the following equilibrium? [The concentration of water in a dilute aqueous solution is 55 M]

A)"1.8 * 10⁵"
B)"385"
C)"1.8 * 10^-5"
D)"-1.8* 10⁵"

Question 6

Which of the following compounds has the highest pK_a?

A)SiH₄
B)H₂S
C)PH₃
D)HCl

Question 7

Which of the following compounds is the strongest acid?

A)CH₃CH₂CH₂COOH
B)CH₃CH₂CHClCOOH
C)CH₃CHClCH₂COOH
D)ClCH₂CH₂CH₂COOH

Question 8

Which of the following compounds is the strongest acid?

A)CH₃COOH
B)ClCH₂COOH
C)CH₃CH₂OH
D)ClCH₂CH₂OH

Question 9

Which of the following is the strongest acid?

A)HCl
B)HI
C)HF
D)HBr

Question 10

Which of the following is the strongest acid?

A)CH₃NH₂
B)CH₃PH₂
C)CH₃OH
D)CH₃SH

Question 11

Which of the following compounds is the strongest acid?

A)CH₃COOH
B)FCH₂COOH
C)ClCH₂COOH
D)BrCH₂COOH

Question 12

Which of the following is the strongest acid?

A)CH₃CH₃
B)CH₃NH₂
C)CH₃OH
D)CH₃F

Question 13

Which of the following compounds is the strongest acid?

A)CF₃OH
B)CF₃CH₂ CH₂OH
C)CF₃CH₂ CH₂ CH₂OH
D)CF₃CH₂ CH₂ CH₂CH₂OH

Question 14

Which of the following is the strongest base?

A)iodide anion, I^-
B)fluoride anion, F^-
C)bromide anion, Br1^-
D)chloride anion, Cl^-

Question 15

Which of the following compounds is the strongest acid?

A)CH₃OCH₃
B)CH₃CH₂OH
C)CH₃CHO
D)CH₃CO₂H

Question 16

Which of the following is the strongest base?

A)NaOH
B)NaCO₃
C)H₂O
D)CH₃OH

Question 17

Which of the following compounds is the strongest acid?

A)HF
B)H₂O
C)NH₃
D)CH₄

Question 18

Which of the following is easiest to deprotonate?

A)CH₄
B)CH₃CH₃
C)CH₂=CH₂
D)HC $\equiv$ CH

Question 19

Which of the following anions is the strongest base?

A)CH₃COO^-
B)HO^-
C)NH₂^-
D)Cl^-

Question 20

Which of the following anions is the strongest base?

A)NH₂^-
B)NH₃
C)CH₃CH=N^-
D)CH₃C $\equiv$ N

Question 21

Which of the following is a feature of a Lewis acid?

A)proton donor
B)proton acceptor
C)electron pair donor
D)electron pair acceptor

Question 22

Which sets of curved arrows accounts for the protonation of propene with HI?

A)1
B)2
C)3
D)4

Question 23

Which of the following terms describes the role of ethanol in the acid-base reaction shown?

A)Brønsted-Lowry acid
B)Brønsted-Lowry base
C)Lewis acid
D)Lewis base

Question 24

Which of the following is present in the highest concentration upon dissolution of H₂SO₄ in water?

A)H₂SO₄
B)H⁺
C)H₃O⁺
D)HO^-

Question 25

Which set of curved arrows accounts for the deprotonation of an acid (A-H) by a base (:B)?

A)1
B)2
C)3
D)4

Question 26

What is the value of the equilibrium constant, K_eq, for the following reaction?

A)"10¹³"
B)"10^-13"
C)"13"
D)"¹/₁₃"

Question 27

Which of the following terms describes the reactivity of trimethylamine, (CH₃)₃N?

A)Brønsted-Lowry acid and Lewis acid
B)Brønsted-Lowry base and Lewis base
C)Lewis acid and not a Brønsted-Lowry acid
D)Lewis base and not a Brønsted-Lowry base

Question 28

Which of the following terms describes the role of ethene in the acid-base reaction shown?

A)Brønsted-Lowry acid
B)Brønsted-Lowry base
C)Lewis acid
D)Lewis base

Question 29

Which of the following is a feature of a Lewis base?

A)proton donor
B)proton acceptor
C)electron pair donor
D)electron pair acceptor

Question 30

Which of the following is a Lewis acid but not a Brønsted-Lowry acid?

A)CH₃COOH
B)AlCl₃
C)H₂O
D)CH₃OH

Question 31

Which of the following terms describes the role of ethanol in the acid-base reaction shown?

A)Brønsted-Lowry acid
B)Brønsted-Lowry base
C)Lewis acid
D)Lewis base

Question 32

Which species is the conjugate acid in the following acid-base reaction?

A)1
B)2
C)3
D)4

Question 33

Which of the following compounds has the lowest pK_a?

A)H₂O
B)H₂S
C)H₂Se
D)H₂Te

Question 34

Which of the following compounds has the highest pK_a?

A)NH₃
B)H₂O
C)HCl
D)CH₄

Question 35

What is the value of the equilibrium constant, K_eq, for the following reaction?

A)"10⁹"
B)"10^-9"
C)"9"
D)"¹/₉"

Question 36

Which species is the conjugate acid in the following acid-base reaction?

A)1
B)2
C)3
D)4

Question 37

Which of the following compounds has the lowest pK_a?

A)H₂O
B)HBr
C)NH₃
D)CH₄

Question 38

Which of the following terms describes the reactivity of boron tribromide, BBr₃?

A)Brønsted-Lowry acid and Lewis acid
B)Brønsted-Lowry base and Lewis base
C)Lewis acid and not a Brønsted-Lowry acid
D)Lewis base and not a Brønsted-Lowry base

Question 39

Which of the following terms describes the role of ethyne in the acid-base reaction shown?

A)Brønsted-Lowry acid
B)Brønsted-Lowry base
C)Lewis acid
D)Lewis base

Question 40

Which of the following is present in the highest concentration upon dissolution of acetic acid in water?

A)OH^-
B)H₃O⁺
C)CH₃COOH
D)CH₃COOH⁺

Question 41

Which of the following has the highest bond dissociation energy?

A)HF
B)HCl
C)HBr
D)HI

Question 42

Which of the following energy diagrams best represents the changes in energy during addition of HBr to an alkene?

A)1
B)2
C)3
D)4

Question 43

Which of the following has a pK_a value of approximately 25?

A)CH₃CH₃
B)CH₂=CH₂
C)HC $\equiv$ CH
D)CH₃CH₂OH

Question 44

Which of the following equations is correct?

A)" $\Delta$ G ^$\circ$ = $\Delta$ H ^$\circ$ - T $\Delta$ S ^$\circ$ "
B)" $\Delta$ H ^$\circ$ = $\Delta$ G ^$\circ$ - T $\Delta$ S ^$\circ$ "
C)" $\Delta$ G ^$\circ$ = $\Delta$ H ^$\circ$ - $\Delta$ S ^$\circ$ "
D)" $\Delta$ G ^$\circ$ = $\Delta$ H ^$\circ$ - $\Delta$ S ^$\circ$ /T"

Question 45

Which of the following has a pK_a value of approximately 16?

A)HBr
B)CH₃COOH
C)CH₃CH₂OH
D)HC $\equiv$ CH

Question 46

In the following list, there are two organic Lewis bases.

Question 47

Under which of the following conditions will a reaction be spontaneous when $\Delta$ H ^$\circ$ > 0?

A)"T $\Delta$ S ^$\circ$ = 0"
B)"T $\Delta$ S ^$\circ$ > $\Delta$ H ^$\circ$ "
C)"T $\Delta$ S ^$\circ$ < 0 ^$\circ$ "
D)" $\Delta$ G ^$\circ$ = 0"

Question 48

Which of the following concepts can be used to rationalize the observation that acetic acid is a stronger acid than methanol?

A)electronegativity
B)resonance
C)valence shell electron pair repulsion theory
D)Pauli exclusion principle

Question 49

What is the approximate pK_a value of HCl?

A)-7
B)5
C)16
D)51

Question 50

Which of the following statements is not true?

A)"The position of the equilibrium for an exergonic reaction favors products"
B)"The products of an exergonic reaction have a higher Gibbs free energy than the reactants."
C)"The equilibrium constant of a reaction for which $\Delta$ G ^$\circ$ = 0 is 1."
D)" $\Delta$ G ^$\circ$ = $\Delta$ H ^$\circ$ -T $\Delta$ S ^$\circ$ "

Question 51

Which of the following is a definition of the rate-determining step of a reaction mechanism?

A)the first step
B)the last step
C)the step that crosses the highest energy barrier
D)the most exothermic step

Question 52

An acid with a low pK_a is a strong acid and has a weak conjugate base.

Question 53

Which of the following energy diagrams represents the fastest reaction?

A)1
B)2
C)3
D)4

Question 54

What is the approximate pK_a value of acetic acid?

A)-7
B)5
C)16
D)51

Question 55

Which of the following is a feature of a Brønsted-Lowry base?

A)proton donor
B)proton acceptor
C)electron pair donor
D)electron pair acceptor

Question 56

Which of the following is a feature of a Brønsted-Lowry acid?

A)proton donor
B)proton acceptor
C)electron pair donor
D)electron pair acceptor

Question 57

In the following list, there are four Lewis acids, CH₃OH, HCl, BCl₃ and FeBr₃.

Question 58

Which atom in the following structure is preferentially protonated by a strong acid?

A)i
B)ii
C)iii
D)iv

Question 59

Which of the following energy diagrams represents the slowest reaction?

A)1
B)2
C)3
D)4

Question 60

Which of the following is a definition of the activation energy of a reaction?

A)the difference in Gibbs free energy between the reactants and the transition state
B)the difference in Gibbs free energy between the reactants and the intermediate
C)the difference in Gibbs free energy between the reactants and the product
D)the difference in Gibbs free energy between the transition state and the product

Question 61

The following correctly shows the electron flow for the given reaction.

Question 62

A species that lies at an energy maximum during an individual step in a reaction is termed ____________________.

Question 63

Complete the equation below for the protonation of cyclohexene with HCl. Show the movement of pairs of electrons with curved arrows and provide the structures of the conjugate acid and conjugate base.

Question 64

____________________ is defined by the following equation.
$\Delta$ G ^$\circ$ = -RT ln K_eq

Question 65

A reaction in which the free energy of the products is greater than the reactants is termed____________________ .

Question 66

Use curved arrows to show the movement of pairs of electrons in the following acid-base reaction and show the structures of the conjugate acid and conjugate base.

Question 67

Complete the equation below for the protonation of 2-butene with HBr. Show the movement of pairs of electrons with curved arrows and provide the structures of the conjugate acid and conjugate base.

Question 68

Which acid has the strongest conjugate base?

Question 69

Consider the following reaction coordinate diagram. This reaction is endergonic.

Question 70

The following is generic depiction of a reaction using the curve arrow formalism. In this reaction electrons move from C to B and A will have a positive charge in the product.

Question 71

A reaction where $\Delta$ G ^$\circ$ is positive is _____________.

Question 72

Which acid will be almost completely deprotonated by NaOH?

Question 73

Consider the following reaction coordinate diagram. The free energy of activation is represented by the letter C.

Question 74

Use curved arrows to show the movement of pairs of electrons in the following acid-base reaction and show the structures of the conjugate acid and conjugate base.

Question 75

Which acid has the smallest K_a?

Question 76

The structure of the alkaloid ephedrine is shown below. When ephedrine is placed in the presence of an acid, the -OH group will be protonated.

Question 77

Indole is pleasant smelling in highly dilute solutions and has been used in perfumery. When indole is placed in the presence of a strong base the nitrogen atom will be deprotonated.

Question 78

Consider the following reaction coordinate diagram. The transition state is represented by the letter B.

Question 79

Indole is pleasant smelling in highly dilute solutions and has been used in perfumery. Indole can be classified as a Brønsted-Lowry base but not as a Lewis base..

Question 80

The energy needed by reactants to reach the transition state is the____________________,