Q: What is the correct expression for the ion product of water ($$K_w) at 25$$°C?

$$K_w = [H_3O^+][OH^-] = 1.0 \times 10$$^{-14}$$

Q: A solution has a pH of 4.35. What is the hydronium ion concentration in this solution?

$$[H_3O^+] = 10$$^{-4.35}$$ \text{ M}$$

Q: If the pH of a solution is 11.28, what is the hydroxide ion concentration?

$$[OH^-] = 10$$^{-2.72}$$ \text{ M}$$

Q: A 0.015 M solution of HCl is prepared. What is the hydroxide ion concentration in this solution at 25°C?

$$[OH^-] = \frac{1.0 \times 10$$^{-14}$$}{0.015} = 6.7 \times 10$$^{-13}$$ \text{ M}$$

Q: Which equation correctly relates pH and pOH in aqueous solution at 25°C?

$$\text{pH} + \text{pOH} = 14.00$$

Q: A student measures the pH of a solution of acetic acid (CH3COOH) and finds it to be 2.89. What is the hydronium ion concentration?

$$[H_3O^+] = 10$$^{-2.89}$$ \text{ M}$$

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 based on the number of ionizable protons?

Accepted Answer

Citric acid; polyprotic

Question 2

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

Accepted Answer

An acid is a proton donor and a base is a proton acceptor.

Question 3

Which pair of species constitutes a conjugate acid–base pair?

Accepted Answer

NH4+ and NH3

Question 4

What is the correct expression for the ion product of water ($$K_w) at 25$$°C?

Accepted Answer

$$K_w = [H_3O^+][OH^-] = 1.0 	imes 10$$^{-14}$$

Question 5

A solution has a pH of 4.35. What is the hydronium ion concentration in this solution?

Accepted Answer

$$[H_3O^+] = 10$$^{-4.35}$$ 	ext{ M}$$

Question 6

If the pH of a solution is 11.28, what is the hydroxide ion concentration?

Accepted Answer

$$[OH^-] = 10$$^{-2.72}$$ 	ext{ M}$$

Question 7

Which of the following statements about strong acids is correct?

Accepted Answer

Strong acids are completely ionized in aqueous solution.

Question 8

A 0.015 M solution of HCl is prepared. What is the hydroxide ion concentration in this solution at 25°C?

Accepted Answer

$$[OH^-] = \frac{1.0 	imes 10$$^{-14}$$}{0.015} = 6.7 	imes 10$$^{-13}$$ 	ext{ M}$$

Question 9

Which equation correctly relates pH and pOH in aqueous solution at 25°C?

Accepted Answer

$$	ext{pH} + 	ext{pOH} = 14.00$$

Question 10

Which of the following acids is classified as a weak acid?

Accepted Answer

CH3COOH

Question 11

What happens to the degree of ionization of a weak acid as the solution becomes more dilute?

Accepted Answer

It increases.

Question 12

Which formula represents the acid ionization constant ($$K_a) $$for a monoprotic acid HA?

Accepted Answer

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

Question 13

A student measures the pH of a solution of acetic acid (CH3COOH) and finds it to be 2.89. What is the hydronium ion concentration?

Accepted Answer

$$[H_3O^+] = 10$$^{-2.89}$$ 	ext{ M}$$

Question 14

Which of the following statements about polyprotic acids is correct?

Accepted Answer

The first ionization constant ($$K_{a1}) is $$usually much larger than subsequent $$K_a$$ values.

Question 15

For a 3.0 M solution of phosphoric acid ($$H_3PO_4$$), which ion is present in the highest concentration after the first ionization step?

Accepted Answer

$$H_2PO_4^-$$

Question 16

Which of the following molecules is amphiprotic?

Accepted Answer

H2O

Question 17

A solution contains 0.100 M CH3COOH. If the percent ionization is found to be 1.3%, what is the concentration of ionized CH3COOH?

Accepted Answer

$$0.0013 	imes 0.100 	ext{ M} = 0.0013 	ext{ M}$$

Question 18

Which of the following best describes the relationship between $$K_a$$ and acid strength?

Accepted Answer

A larger $$K_a$$ means a stronger acid.

Question 19

Which of the following is a real-world application of acid–base chemistry?

Accepted Answer

Determining the pH of blood to diagnose medical conditions.

Acids and Bases: Concepts, Ionization, and Calculations

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