Question 1

Which of the following aryl amines is the strongest base?
A)Aniline
B)p-Trimethylammonium aniline
C)p-Methoxyaniline
D)p-Trifluoromethylaniline
E)p-Chloroaniline

Accepted Answer

p-Methoxyaniline is the strongest base among the given options because the methoxy group is an electron-donating group via resonance, which increases the electron density on the nitrogen atom, making it more basic.

Question 2

Which of the following bases has a conjugate acid with the smallest pK_a? A)p-Methylaniline B)p-Methoxyaniline C)Hexylamine D)p-Nitroaniline E)Dipropylamine

Accepted Answer

p-Nitroaniline has a conjugate acid with the smallest pKa because the nitro group is a strong electron-withdrawing group. This increases the stability of the conjugate acid by delocalizing the positive charge, thus making it a stronger acid compared to the other options.

Question 3

Arrange the following compounds in order of increasing basicity (least to most)in aqueous solution: 
A)IV < II < I < III
B)III < II < IV < I
C)II < I < III < IV
D)II < III < I < IV
E)Cannot be determined from information given

Accepted Answer

The basicity of a compound depends on the availability of lone pair electrons. In compound IV, nitrogen is connected to two electronegative oxygen atoms, making the nitrogen less basic. In compound II, nitrogen is connected to a less electronegative carbon atom, making the lone pair electrons more available, making it more basic than IV. In compound I, there are two nitrogen atoms, making it more basic than II. In compound III, the nitrogen is part of a ring, making it the most basic among the four compounds. Therefore, the order of increasing basicity is II < I < III < IV, which is given by choice C.

Question 4

Which of these would be predicted to have the largest pK_a? A)I B)II C)III D)IV E)V

Accepted Answer

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Question 5

Which of these is the weakest acid? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

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Question 6

Arrange the following compounds in order of increasing basicity (least to most)in aqueous solution: 
A)IV < II < I < III
B)III < II < IV < I
C)II < I < III < IV
D)II < III < I < IV
E)Cannot be determined from information given

Accepted Answer

Basicity is related to the availability of lone pair of electrons on the nitrogen atom. In compound I, the nitrogen atom is participating in resonance with the adjacent carbonyl group, which reduces the availability of lone pair of electrons, making it the least basic. In compound IV, the nitrogen atom has two electron-withdrawing groups, i.e. the carbonyl group and the nitro group, making it the most basic compound. Compound II has one electron-withdrawing group, i.e. the carbonyl group, making it more basic than compound I but less basic than compound III. Compound III has no electron-withdrawing groups and contains a secondary amine, which is more basic than primary amine (compound II). Therefore, the correct order of increasing basicity is II < I < III < IV.

Question 7

Arrange the following amines in order of decreasing basicity (most to least)in aqueous solution: 
A)IV > II > I > III
B)III > II > IV > I
C)III > I > II > IV
D)II > III > I > IV
E)Cannot be determined from information given

Accepted Answer

The basicity of amines depends on the availability of lone pair electrons on nitrogen. The more the availability, the higher the basicity will be. 
In compound III, there are two lone pairs of electrons on the nitrogen atom that are readily available for reaction, making it the most basic. 
In compound I, there is only one lone pair of electrons, making it less basic than III. 
In compound II, the nitrogen is part of an aromatic ring, which delocalizes the lone pair of electrons and makes it less available for reaction. 
In compound IV, the nitrogen is part of a tertiary amine, which has an alkyl group bonded to it that reduces the availability of lone pairs, and therefore decreases its basicity even further. Thus, the correct order of basicity is III > I > II > IV.

Question 8

Which of these would be predicted to have the smallest pK_a? A)I B)II C)III D)IV E)V

Accepted Answer

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Question 9

Which of the following compounds would be the weakest base? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

In order to determine the weakest base among the given compounds, we need to identify the compound with the most stable conjugate acid. The conjugate acid of compound I (HI) is a strong acid, meaning it will be almost completely dissociated in water, resulting in a stable conjugate base (I-). Therefore, compound I will be the weakest base among the given choices. The other compounds have weaker conjugate acids, meaning their conjugate bases will be more basic.

Question 10

Which of the following compounds would be the strongest base? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

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Question 11

Which of the following bases has a conjugate acid with the smallest pK_a? A)I B)II C)III D)IV E)V

Accepted Answer

The smaller the pKa of the conjugate acid, the stronger the base. The larger the anion, the more stable it is, leading to weaker basicity. Iodide (I-) is larger than the rest of the anions listed, resulting in the least stable anion and the strongest base. Thus, its conjugate acid (HI) will have the smallest pKa, making choice A the best answer.

Question 12

Which of the following bases has a conjugate acid with the largest pK_a? A)I B)II C)III D)IV E)V

Accepted Answer

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Question 13

Which of the following aryl amines is the weakest base?
A)Aniline
B)p-Trimethylammonium aniline
C)p-Methoxyaniline
D)p-Trifluoromethylaniline
E)p-Chloroaniline

Accepted Answer

p-Trimethylammonium aniline has a positive charge on the nitrogen atom, making it less basic and more acidic than aniline, p-Methoxyaniline, p-Trifluoromethylaniline, and p-Chloroaniline. Therefore, it is the weakest base among the given options.

Question 14

Which would be the weakest base?
A)p-Methylaniline
B)p-Methoxyaniline
C)Hexylamine
D)p-Nitroaniline
E)Dipropylamine

Accepted Answer

p-Nitroaniline is the weakest base among the options given. This is because the nitro group (-NO2) is a strong electron-withdrawing group. It pulls electron density away from the aniline nitrogen, which decreases the nitrogen's ability to donate its lone pair of electrons, thus weakening its basicity.

Question 15

In aqueous solution,which of the following bases has the conjugate acid that possesses the smallest value for pK_a? A)C₆H₅NH₂ B)NH₃ C)(CH₃CH₂)₃N D)(CH₃CH₂)₂NH E)CH₃CH₂CH₂NH₂

Accepted Answer

The conjugate acid of $CH_3CH_2NH_2$ (choice A) is $CH_3CH_2NH_3^+$, which has a smaller pKa (or pKS) value compared to the conjugate acids of the other bases listed. This is because the ethyl group is less electron-donating compared to the more alkylated amines, making the conjugate acid more stable and thus more acidic.

Question 16

Which of these is the strongest acid? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

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Question 17

Which of the following bases has a conjugate acid with the smallest pK_a? A)I B)II C)III D)IV E)Cannot be determined from information given

Accepted Answer

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Question 18

Which of these is the strongest acid? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

The strength of an acid depends on its ability to donate a proton (H+ ion). In option B, the presence of four -NO2 groups increases the electron-withdrawing effect and destabilizes the O-H bond, making it easier to release a proton. Therefore, option II is the strongest acid.

Question 19

Arrange the following amines in order of increasing basicity (least to most)in aqueous solution: 
A)IV < II < I < III
B)III < II < IV < I
C)III < I < II < IV
D)II < III < I < IV
E)Cannot be determined from information given

Accepted Answer

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Question 20

Which of these compounds is soluble in dilute sodium hydroxide solution? 
A)I
B)II
C)III
D)IV
E)V

Accepted Answer

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Quiz 20: Amines

Which of the following aryl amines is the strongest base?

Which of the following bases has a conjugate acid with the smallest pK_a?

Arrange the following compounds in order of increasing basicity (least to most) in aqueous solution:

Which of these would be predicted to have the largest pK_a?

Which of these is the weakest acid?

Arrange the following compounds in order of increasing basicity (least to most) in aqueous solution:

Arrange the following amines in order of decreasing basicity (most to least) in aqueous solution:

Which of these would be predicted to have the smallest pK_a?

Which of the following compounds would be the weakest base?

Which of the following compounds would be the strongest base?

Which of the following bases has a conjugate acid with the smallest pK_a?

Which of the following bases has a conjugate acid with the largest pK_a?

Which of the following aryl amines is the weakest base?

Which would be the weakest base?

In aqueous solution,which of the following bases has the conjugate acid that possesses the smallest value for pK_a?

Which of these is the strongest acid?

Which of the following bases has a conjugate acid with the smallest pK_a?

Which of these is the strongest acid?

Arrange the following amines in order of increasing basicity (least to most) in aqueous solution:

Which of these compounds is soluble in dilute sodium hydroxide solution?

Quiz 20: Amines

Which of the following aryl amines is the strongest base?

Which of the following bases has a conjugate acid with the smallest pKa?

Arrange the following compounds in order of increasing basicity (least to most) in aqueous solution:

Which of these would be predicted to have the largest pKa?

Which of these is the weakest acid?

Arrange the following compounds in order of increasing basicity (least to most) in aqueous solution:

Arrange the following amines in order of decreasing basicity (most to least) in aqueous solution:

Which of these would be predicted to have the smallest pKa?

Which of the following compounds would be the weakest base?

Which of the following compounds would be the strongest base?

Which of the following bases has a conjugate acid with the smallest pKa?

Which of the following bases has a conjugate acid with the largest pKa?

Which of the following aryl amines is the weakest base?

Which would be the weakest base?

In aqueous solution,which of the following bases has the conjugate acid that possesses the smallest value for pKa?

Which of these is the strongest acid?

Which of the following bases has a conjugate acid with the smallest pKa?

Which of these is the strongest acid?

Arrange the following amines in order of increasing basicity (least to most) in aqueous solution:

Which of these compounds is soluble in dilute sodium hydroxide solution?

Which of the following bases has a conjugate acid with the smallest pK_a?

Which of these would be predicted to have the largest pK_a?

Which of these would be predicted to have the smallest pK_a?

Which of the following bases has a conjugate acid with the smallest pK_a?

Which of the following bases has a conjugate acid with the largest pK_a?

In aqueous solution,which of the following bases has the conjugate acid that possesses the smallest value for pK_a?

Which of the following bases has a conjugate acid with the smallest pK_a?