Question 1

Which of the following statements best describes an Arrhenius acid?

Accepted Answer

A substance that dissociates in water to give $\mathrm{H_3O^+}$ ions.

Question 2

Which of the following is the correct expression for the acid dissociation constant $K_a$ for the generic acid $HA$ in water?

Accepted Answer

$K_a = \frac{[H_3O^+][A^-]}{[HA]}$

Question 3

Which of the following compounds is expected to be the strongest acid based on periodic trends?

Accepted Answer

$\mathrm{HF}$

Question 4

Which of the following statements about conjugate acids and bases is correct?

Accepted Answer

A conjugate acid is formed when a base accepts a proton.

Question 5

Which of the following factors will increase the acidity of a molecule?

Accepted Answer

Increasing the size of the atom bearing the negative charge in the conjugate base.

Question 6

Which of the following best explains why acetic acid ($\mathrm{CH_3COOH}$) is more acidic than ethanol ($\mathrm{CH_3CH_2OH}$)?

Accepted Answer

The conjugate base of acetic acid is stabilized by resonance.

Question 7

Which of the following is a correct statement about the relationship between acid strength and conjugate base strength?

Accepted Answer

A strong acid has a weak conjugate base.

Question 8

Which of the following functional groups contains a carbonyl group bonded to a nitrogen atom?

Accepted Answer

Amide

Question 9

Which of the following molecules is amphoteric in water?

Accepted Answer

$\mathrm{H_2O}$

Question 10

Which of the following best describes a Lewis acid?

Accepted Answer

A species that accepts a pair of electrons.

Question 11

Which of the following compounds is an example of an ether?

Accepted Answer

$\mathrm{CH_3OCH_3}$

Question 12

Which of the following statements about acid-base equilibria is correct?

Accepted Answer

The equilibrium always favors the formation of the weaker acid and weaker base.

Question 13

Which of the following functional groups is present in both aldehydes and ketones?

Accepted Answer

Carbonyl group ($C=O$)

Question 14

Which of the following changes will most likely increase the acidity of a carboxylic acid?

Accepted Answer

Replacing a hydrogen on the alpha carbon with a chlorine atom.

Question 15

Which of the following best explains why $\mathrm{HI}$ is a stronger acid than $\mathrm{HF}$, even though fluorine is more electronegative than iodine?

Accepted Answer

The bond between H and I is weaker and easier to break than the bond between H and F.

Question 16

Which of the following is the correct $pK_a$ value for water ($\mathrm{H_2O}$)?

Accepted Answer

$pK_a = 15.7$

Question 17

Which of the following is a correct example of a Brønsted–Lowry base?

Accepted Answer

$\mathrm{NH_3}$

Question 18

Which of the following best describes the effect of resonance on acidity?

Accepted Answer

Resonance delocalization of negative charge in the conjugate base increases acidity.

Question 19

Which of the following is the correct order of acidity for the following compounds: $\mathrm{CH_4}$, $\mathrm{NH_3}$, $\mathrm{H_2O}$, $\mathrm{HF}$?

Accepted Answer

$\mathrm{HF} > \mathrm{H_2O} > \mathrm{NH_3} > \mathrm{CH_4}$

Question 20

Which of the following is a correct example of a nucleophile in a Lewis acid-base reaction?

Accepted Answer

$\mathrm{Cl^-}$ attacking $\mathrm{CH_3Cl}$

Acids, Bases, and Functional Groups in Organic Chemistry

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