Q: A solution is prepared by dissolving 0.10 M HCl in water. What is the pH of this solution at 25°C?

$$\text{pH} = -\log(0.10) = 1.00$$

Q: Which of the following acids is classified as a strong acid?

Hydrochloric acid ($$\text{HCl})$$

Q: Which equation correctly represents the autoionization of water?

$$\text{H}_2\text{O} + \text{H}_2\text{O} \rightleftharpoons \text{H}_3\text{O}^+ + \text{OH}^-$$

Q: Calculate the pH of a 0.025 M NaOH solution at 25°C.

$$\text{pH} = 14 - (-\log(0.025)) = 12.40$$

Q: Which equation represents the Henderson–Hasselbalch equation for calculating the pH of a buffer?

$$\text{pH} = \text{p}K_a + \log\left(\frac{[\text{A}^-]}{[\text{HA}]}\right)$$

Question 1

Which of the following statements best describes the Arrhenius definition of acids and bases?

Accepted Answer

Acids produce H+ ions in aqueous solution, and bases produce OH− ions in aqueous solution.

Question 2

A solution is prepared by dissolving 0.10 M HCl in water. What is the pH of this solution at 25°C?

Accepted Answer

$$	ext{pH} = -\log(0.10) = 1.00$$

Question 3

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

Accepted Answer

Hydrochloric acid ($$	ext{HCl})$$

Question 4

Which equation correctly represents the autoionization of water?

Accepted Answer

$$	ext{H}_2	ext{O} + 	ext{H}_2	ext{O} ightleftharpoons 	ext{H}_3	ext{O}^+ + 	ext{OH}^-$$

Question 5

A buffer solution is most effective when:

Accepted Answer

The concentrations of acid and base are approximately equal.

Question 6

Which of the following best explains why HF is a weak acid while HCl is a strong acid?

Accepted Answer

HF has a stronger H–F bond, making it harder to ionize.

Question 7

What is the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 8

Calculate the pH of a 0.025 M NaOH solution at 25°C.

Accepted Answer

$$	ext{pH} = 14 - (-\log(0.025)) = 12.40$$

Question 9

Which of the following is a property of bases?

Accepted Answer

Bases feel slippery and turn red litmus paper blue.

Question 10

A student mixes 0.10 M acetic acid and 0.10 M sodium acetate in water. What is the primary function of this mixture?

Accepted Answer

To create a buffer solution that resists changes in pH.

Question 11

Which equation represents the Henderson–Hasselbalch equation for calculating the pH of a buffer?

Accepted Answer

$$	ext{pH} = 	ext{p}K_a + \log\left(\frac{[	ext{A}^-]}{[	ext{HA}]}ight)$$

Question 12

During the titration of a weak acid with a strong base, what is the pH at the equivalence point?

Accepted Answer

The pH is greater than 7.

Question 13

Which of the following salts will produce a basic solution when dissolved in water?

Accepted Answer

NaF

Question 14

What is the effect of adding a common ion (such as sodium acetate) to a solution of acetic acid?

Accepted Answer

It decreases the concentration of $$	ext{H}_3	ext{O}^+$$ and increases the pH.

Question 15

Which of the following statements about polyprotic acids is correct?

Accepted Answer

The first ionization constant ($$K_{a1}) is $$always greater than the second ($$K_{a2}).$$

Question 16

Which of the following best describes the relationship between electronegativity and oxyacid strength?

Accepted Answer

The more electronegative the central atom, the stronger the oxyacid.

Question 17

A solution has $$[	ext{H}_3	ext{O}^+] = 1.0 	imes 10$$^{-9}$$ M. What is its pH?

Accepted Answer

$$	ext{pH} = -\log(1.0 	imes 10$$^{-9}$$) = 9$$

Question 18

Which of the following is true about the pH scale?

Accepted Answer

A pH of 7 is neutral.

Question 19

Which of the following best describes the action of a buffer when a strong acid is added?

Accepted Answer

The buffer's conjugate base reacts with the added acid to form more weak acid.

Acid-Base Equilibria: Mini-Textbook Study Guide for Biology Students

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