Question 1

Which of the following statements best describes the Brønsted-Lowry definition of an acid?

Accepted Answer

A substance that donates a hydrogen ion (proton; H+) to a base.

Question 2

Which equation correctly represents the acid dissociation constant ($$K_a) $$for the reaction $$\mathrm{H_2O} + \mathrm{HA} \rightleftharpoons \mathrm{H_3O^+} + \mathrm{A^-}$$?

Accepted Answer

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

Question 3

Which of the following functional groups is most likely to behave as an acid in aqueous solution?

Accepted Answer

Carboxylic acid

Question 4

A drug molecule contains both a carboxylic acid and a secondary amine. What term best describes its acid/base properties?

Accepted Answer

Amphoteric

Question 5

Which of the following statements about pKa is correct?

Accepted Answer

The smaller the value of pKa, the stronger the acid.

Question 6

Arrange the following acids in order of increasing acidity: HF, HCl, HBr, HI.

Accepted Answer

HF \u003c HCl \u003c HBr \u003c HI

Question 7

Which property is most directly influenced by the electronegativity of the atom attached to hydrogen in an acid?

Accepted Answer

Acidity

Question 8

What effect do electron withdrawing groups (EWGs) have on the acidity of a molecule?

Accepted Answer

EWGs increase acidity by stabilizing the conjugate base.

Question 9

Which of the following is a common acidic functional group found in drugs and is resonance stabilized upon ionization?

Accepted Answer

Carboxylic acid

Question 10

Phenols are considered weak acids compared to carboxylic acids. What is the primary reason for this difference?

Accepted Answer

Carboxylic acids have greater resonance stabilization in their conjugate base.

Question 11

Which of the following drugs is used in the UK as a sodium salt due to its acidic nature and poor water solubility?

Accepted Answer

Warfarin

Question 12

If the pKa of a drug is 4 and the pH of the stomach is 2, what is the predominant form of the drug in the stomach?

Accepted Answer

Unionized (acid form)

Question 13

Which of the following statements about the conjugate base of a strong acid is correct?

Accepted Answer

It has little affinity for the proton.

Question 14

Which factor explains why HI is a stronger acid than HF, despite fluorine being more electronegative?

Accepted Answer

HI has a weaker H-I bond, making proton loss easier.

Question 15

Which of the following is NOT an electron withdrawing group (EWG)?

Accepted Answer

-$$CH_3$$

Question 16

A molecule with a pKa of 2 is considered:

Accepted Answer

A reasonably strong acid

Question 17

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

Accepted Answer

Resonance stabilizes the conjugate base, increasing acidity.

Question 18

Which of the following statements about the solubility of drug salts is correct?

Accepted Answer

Sodium salts of weak acids are more soluble than the free acid.

Question 19

Which of the following acids has the highest pKa value?

Accepted Answer

$$CH_4$$

Acids, Bases, and the Chemistry of Organic Functional Groups

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