Question 1

Which acid is primarily responsible for the sour taste in citrus fruits, as shown in the first image, and what is its classification in terms of proton donation?

Accepted Answer

Citric acid; polyprotic acid

Question 2

According to the Brønsted–Lowry theory, which statement best describes an acid?

Accepted Answer

An acid is a substance that donates a proton ($$H^+).$$

Question 3

Given the molecular model in the second image, which molecule is represented and what functional group is responsible for its acidic properties?

Accepted Answer

Acetic acid; carboxyl group

Question 4

Which equation correctly represents the self-ionization of water?

Accepted Answer

$$2 \mathrm{H_2O}(l) \rightleftharpoons \mathrm{H_3O^+}(aq) + \mathrm{OH^-}(aq)$$

Question 5

If the pH of a solution is measured as 1.20 (see image with pH meters), what is the concentration of hydronium ions $$[\mathrm{H_3O^+}] in $$the solution?

Accepted Answer

$$[\mathrm{H_3O^+}] = 10$$^{-1.20}$$ \ \mathrm{M}$$

Question 6

Which molecule, shown in the fifth image, is an example of an amino acid and can act as both an acid and a base in aqueous solution?

Accepted Answer

Glycine

Question 7

For a weak acid, which of the following statements is true regarding its degree of ionization as the solution becomes more dilute?

Accepted Answer

The degree of ionization increases with dilution.

Question 8

Which equation correctly relates pH and hydronium ion concentration?

Accepted Answer

$$\mathrm{pH} = -\log [\mathrm{H_3O^+}]$$

Question 9

Which molecule, shown in the ninth image, is responsible for the acidity in vinegar?

Accepted Answer

Acetic acid

Question 10

A solution of sodium acetate ($$\mathrm{NaCH_3COO}) in $$water is expected to be:

Accepted Answer

Basic, because acetate ion is a weak base

Question 11

Which molecule, shown in the tenth image, is fluoroacetic acid, and why is it stronger than acetic acid?

Accepted Answer

It is fluoroacetic acid; the fluorine atom increases acidity by withdrawing electrons.

Question 12

Which molecule, shown in the twelfth image, is a hydrated metal ion and acts as a Lewis acid in water?

Accepted Answer

$$Al(H2O)6^3+$$

Question 13

Which of the following is the correct relationship between the acid ionization constant ($$K_a) $$and the base ionization constant ($$K_b) $$for a conjugate acid–base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 14

Which molecule, shown in the eighth image, is pyridine, and what is its role in acid–base chemistry?

Accepted Answer

It is pyridine; it acts as a weak base due to the lone pair on nitrogen.

Question 15

Which of the following statements about polyprotic acids is correct?

Accepted Answer

The first ionization step has the largest $$K_a$$ value.

Question 16

Which molecule, shown in the thirteenth image, is lactic acid, and what functional group makes it an acid?

Accepted Answer

It is lactic acid; the carboxyl group ($$-COOH) $$makes it an acid.

Question 17

Which of the following best describes the effect of a highly charged, small metal ion (such as $$\mathrm{Al$$^{3+}$$}) on $$the pH of an aqueous solution?

Accepted Answer

It decreases the pH by acting as a Lewis acid and hydrolyzing water.

Acids and Bases: Concepts, Calculations, and Molecular Structure

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