Deck 17: Acids, Bases, and Buffer Solutions: Life in an Aqueous Environment

Question 1

Which one of the following is the correct expression for the ion product of water?

A)
B)
C)
D)
E) log pH * log pOH

Answer 1

Question 2

The pH of human blood is 7.4. Therefore the hydrogen ion concentration in human blood is which of the following?

A) 7.4 M
B) 2.5*10⁷ M
C) 1.6*10³ M
D) 4.0*10^-8 M
E) 7.4* 10^-7 M

Answer 2

4.0*10^-8 M

Question 3

The pH of a 0.005 M solution of hydrobromic acid is which of the following?

A) 1.3
B) 2.1
C) 2.3
D) 2.0
E) 5.0

Answer 3

C

Question 4

A solution of HCl at concentration of 4 *10^-4 mol L^-1 has a pH of which of the following?

A) 2.67
B) 3.21
C) 3.40
D) 4.31
E) 4.0

Question 5

Given the pK_a for ammonium ion is 9.26, what is the pH of 1 L of
Solution which contains 5.35 g of NH₄Cl, and contains the ammonium ion at a concentration of 0.2 mol L^-1? (Molar mass of NH₄Cl = 54.5 g mol^-1.)

A) 7.00
B) 7.65
C) 8.96
D) 9.56
E) 9.95

Question 6

Which of the following acids would you use to make an effective buffer for a reaction at pH 8?

A) Ethanoic acid; K_a = 1.7 *10^-5
B) Diphosphoric acid; K_a = 1.4* 10^-7
C) Tris-hydroxmethylaminoethane; K_a = 8.3 *10^-9
D) Ammonium chloride; K_a = 5.6 *10^-10
E) Sodium bicarbonate; K_a = 5.3 * 10^-11

Question 7

A 0.1 M solution of ethanoic acid is 1.34% ionized. What is the value of K_a for ethanoic acid?

A) K_a = 5.3*10^-11
B) K_a = 1.82* 10^-5
C) K_a = 1.34 *10^-6
D) K_a = 2.67 * 10^-2
E) K_a = 3.01 * 10^-4

Question 8

If the concentration of [OH^-] in an aqueous solution is 0.3 M, what is the pH of that solution?

A) 8.96
B) 10.87
C) 1.45
D) 3.67
E) 13.48

Question 9

Look at the following equilibrium reaction:
Match each chemical species with the term that best describes its role in this reaction scheme.
-Conjugate acid

A) A
B) B
C) C
D) D

Question 10

Look at the following equilibrium reaction:
Match each chemical species with the term that best describes its role in this reaction scheme.
-A
B) B
C) C
D) D

Question 11

Look at the following equilibrium reaction:
Match each chemical species with the term that best describes its role in this reaction scheme.
-A
B) B
C) C
D) D

Question 12

Look at the following equilibrium reaction:
Match each chemical species with the term that best describes its role in this reaction scheme.
-Conjugate base

A) A
B) B
C) C
D) D

Question 13

Which of the following reactions depict the behaviour of an acid? Select any that apply.

A) NH₃ + H⁺ ⇌ NH₄⁺
B) CH₃OOH^{- +} ⇌CH₃COOH
C) CH₃COOH ⇌ CH3COO^- + H⁺
D) H₂O ⇌ H⁺ + OH^-
E) H₂O + H⁺ ⇌ H₃O⁺

Question 14

Which of the following depicts a neutralization reaction?

A) CH₃CH₂COOH ⇌ CH₃CH₂COO^- + H⁺
B) CH₃CH₂COOH + N_aOH $\rightarrow$ CH₃CH₂COONa + H₂O
C) CH₃CH₂COOH + CH₃OH $\rightarrow$ CH₃CH₂COOCH₃ + H₂O
D) CH₃CH₂COOH + H₂O ⇌ CH₃CH₂COO^- + H₃O⁺

Question 15

Which of the following is the weakest acid?

A) Boric acid, K_a = 7.3*10^-10
B) Benzoic acid, K_a = 6.3 *10^-5
C) Sulfurous acid, K_a = 1.2 *10^-2
D) Ethanoic acid, K_a = 1.8 *10^-5
E) Formic acid, K_a = 1.8 *0 10^-4

Question 16

Which of the following statements about buffer solutions are true? Select any that apply.

A) A buffer solution must contain a strong acid.
B) A buffer solution undergoes a neutralization reaction to consume excess OH^- ions.
C) The conjugate acid present in the buffer solution consumes excess H⁺ ions.
D) The components of the buffer solution must be present at high concentrations.
E) A buffer solution can only resist changes in pH when small quantities of an acid or base are added to it.

Question 17

Match the type of compound with the biological environment into which it is most likely to partition.
-Strong acid

A) Bloodstream
B) Lipid membrane

Question 18

Match the type of compound with the biological environment into which it is most likely to partition.
-Weak acid

A) Bloodstream
B) Lipid membrane

Question 19

Match the following amino acids with the most appropriate description of the extent of ionization of their side chains when the pH of their environment has a value of 10.0
-Lysine (pK_a 10.5)

A) Roughly 50% ionized
B) Less than 50% ionized
C) More than 50% ionized

Question 20

Match the following amino acids with the most appropriate description of the extent of ionization of their side chains when the pH of their environment has a value of 10.0
-Arginine (pK_a 12.5)

A) Roughly 50% ionized
B) Less than 50% ionized
C) More than 50% ionized

Question 21

Match the following amino acids with the most appropriate description of the extent of ionization of their side chains when the pH of their environment has a value of 10.0
-Glutamic acid (pK_a 4.1)

A) Roughly 50% ionized
B) Less than 50% ionized
C) More than 50% ionized