Deck 17: Principles of Chemical Reactivity: the Chemistry of Acids and Bases

Question 1

Which equation depicts the hydrogen phosphate ion behaving as a Brønsted-Lowry base in water?

A) HPO₄^2-(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ H₂PO₄^-(aq) + OH^-(aq)
B) HPO₄^2-(aq) + OH^-(aq) $\rightleftharpoons$ PO₄^3-(aq) + H₂O( $\ell$ )
C) HPO₄^2-(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ PO₄^3-(aq) + H₃O⁺(aq)
D) 2 HPO₄^2-(aq) + O^2-(aq) $\rightleftharpoons$ PO₄^3-(aq) + H₂O( $\ell$ )
E) 2 HPO₄^2-(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ 2 H₂O( $\ell$ ) + P₂O₇(s)

Answer 1

HPO₄^2-(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ H₂PO₄^-(aq) + OH^-(aq)

Question 2

At 50°C the autoionization constant for pure water, K_w, is $5.48 \times 10 ^ { - 14 }$ . What is the H₃O⁺ concentration in pure water at 50°C?

A) $5.48 \times 10 ^ { - 14 }$ M
B) 1.01 × 10^-7 M
C) $1.17 \times 10 ^ { - 7 }$ M
D) $2.34 \times 10 ^ { - 7 }$ M
E) 1.01 × 10^-14 M

Answer 2

$2.34 \times 10 ^ { - 7 }$ M

Question 3

Which of the following statements about the reaction below is correct?
HCO₃^-(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ CO₃^2-(aq) + H₃O⁺(aq)

A) H₃O⁺ is an acid and HCO₃^- is its conjugate base.
B) HCO₃^- is an acid and CO₃^2- is its conjugate base.
C) HCO₃^- is an acid and H₂O is its conjugate base.
D) H₂O is an acid and CO₃^2- is its conjugate base.
E) H₃O⁺ is an acid and CO₃^2- is its conjugate base.

Answer 3

HCO₃^- is an acid and CO₃^2- is its conjugate base.

Question 4

Which of the following is the correct equation for the reaction of ammonia in water?

A) NH₃(aq) + H₂O(l) $\rightleftharpoons$ NH₄⁺(aq) + OH?(aq).
B) NH₃(aq) + H₂O(l) $\rightleftharpoons$ NH₂?(aq) + H₃O⁺(aq)
C) NH₃(aq) + H₃O⁺(aq) $\rightleftharpoons$ NH₄⁺(aq) + H₂O(l).
D) NH₃(aq) + OH?(aq) $\rightleftharpoons$ NH₂?(aq) + H₂O(l)
E) NH₃(aq) + H₂O(l) $\rightleftharpoons$ NH₂?(aq) + H₃O⁺(aq) .

Question 5

A Brønsted-Lowry base is defined as a hydroxide ion donor.

Question 6

Which of the following substances is never a Brønsted-Lowry base in an aqueous solution?

A) potassium hydroxide, NaOH(g)
B) sodium hydrogen phosphate, Na₂HPO₄(s)
C) sodium phosphate, Na₃PO₄(s)
D) ammonium chloride, NH₄Cl(g)
E) sodium bicarbonate, NaHCO₃(s)

Question 7

What is the conjugate base of [Fe(H₂O)₆]³⁺(aq)?

A) H₃O⁺
B) [Fe(H₂O)₆]²⁺
C) [Fe(H₂O)₅H₃O]⁴⁺
D) [Fe(H₂O)₅OH]²⁺
E) [Fe(H₂O)₅]³⁺

Question 8

Which of the following equations shows that isoquinoline, C₉H₇N, behaves as a Brønsted-Lowry base in water?

A) C₉H₇N(aq) + H₂O(l) $\rightleftharpoons$ C₉H₇NH⁺(aq) + OH-(aq)
B) C₉H₇N(aq) + H₂O(l) $\rightleftharpoons$ C₉H₆N^-(aq) + H₃O⁺(aq)
C) C₉H₇N(aq) + OH?(aq) $\rightleftharpoons$ C₉H₆N?(aq) + H₂O(l)
D) C₉H₇N(aq) + H₃O⁺(aq) $\rightleftharpoons$ C₉H₇NH⁺(aq) + H₂O(l)
E) C₉H₇NH⁺(aq) + H₂O(l) $\rightleftharpoons$ C₉H₇N(aq) + H₃O⁺(aq)

Question 9

Which of the following does not behave as an amphiprotic species in water?

A) HClO₃
B) HSO₃^-
C) H₃O⁺
D) HS^-
E) HCO₃^-

Question 10

According to the Brønsted-Lowry definition, a base

A) increases the OH- concentration in an aqueous solution.
B) is a strong electrolyte.
C) is a proton acceptor.
D) increases the pH of a solution.
E) is a proton donor.

Question 11

Which of the following pairs of species is not a conjugate acid-base pair?

A) HOCl and OCl^-
B) HNO₂ and NO₂⁺
C) O^2- and OH^-
D) HSO₄^- and SO₄^2-
E) H₂CO₃ and HCO₃^-

Question 12

Which equation depicts aqueous hydrogen sulfide behaving as a Brønsted-Lowry base in water?

A) H₂S(aq) + 2 OH^-(aq) $\rightleftharpoons$ SO₂(aq) + 2 H₂(g)
B) H₂S(aq) + H₃O⁺(aq) $\rightleftharpoons$ H₃S⁺(aq) + H₂O( $\ell$ )
C) H₂S(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ HS^-(aq) + H₃O⁺(aq)
D) HS^-(aq) + H₃O⁺(aq) $\rightleftharpoons$ H₂S(aq) + H₂O( $\ell$ )
E) H₂S(aq) + H₂O( $\ell$ ) $\rightleftharpoons$ H₃S⁺⁺(aq) + OH^-(aq)

Question 13

Which of the following substances is never a Brønsted-Lowry acid in an aqueous solution?

A) sodium dihydrogen phosphate, NaH₂PO₄(s)
B) sodium acetate, NaCH₃CO₂(s)
C) ammonium nitrate, NH₄NO₃(s)
D) hydrogen bromide, HCl(g)
E) sodium bicarbonate, NaHCO₃(s)

Question 14

Molecules or ions that can alternately behave as either a Brønsted-Lowry acid or base are called

A) polyanions.
B) hydronium ions.
C) polyprotic acids or bases.
D) conjugate acids or bases.
E) amphiprotic.

Question 15

Which are the Brønsted-Lowry bases in the following equilibrium?
CH₃COO^-(aq) + H₂O(l) $\rightleftharpoons$ CH₃COOH(aq) + OH^-(aq)

A) CH₃COO^- and OH^-
B) H₂O and OH^-
C) H₂O, CH₃COOH, and OH^-
D) CH₃COO^- and CH₃COOH
E) H₂O and CH₃COOH

Question 16

Which of the following statements is/are consistent with the Brønsted-Lowry concept of acids and bases?

Question 17

What is the conjugate base of HPO₄^3- in aqueous solution?

A) not possible
B) PO₄^3-
C) HPO₄2−
D) H₂PO₄−
E) H₃PO₄

Question 18

A conjugate acid-base pair consists of two species that may differ by one proton.

Question 19

Which of the following species is amphiprotic in aqueous solution?

A) CHNH₃⁺
B) H₃O⁺
C) HF
D) OCl−
E) H₂PO₄-

Question 20

Which one of the following aqueous solutions will have a pH of 2.00 at 25 °C? (K_w = 1.01 × 10^-14)

A) 0.020 M HNO₃
B) 2.0 M NaOH
C) 10.0 M HBr
D) 10.0 M KCl
E) 0.010 M HCl

Question 21

What is the H₃O⁺ concentration in 0.0072 M NaOH(aq) at 25 °C? (K_w = 1.01 × 10^-14)

A) 1.4 × 10^-12 M
B) 7.2 × 10^-3 M
C) 1.0 × 10^-14 M
D) 1.0 × 10^-7 M
E) 7.2 × 10^-17 M

Question 22

What is the hydronium-ion concentration in a solution formed by combining 750 mL of 0.10 M NaOH with 250 mL of 0.30 M HCl? NaOH(aq) + HCl(aq) → NaCl(aq) + H₂O(l)

A) 0.075 M
B) 1.7 × 10^-13 M
C) 1.0 × 10^-7 M
D) 0.30 M
E) 0.10 M

Question 23

The H₃O⁺ concentration of a solution is 5.9 × 10^-6 M. What is the pH of the solution?

A) 6.44
B) 3.40
C) 2.00
D) 5.23
E) 9.74

Question 24

Which of the following is the correct hydroxide ion (OH^-) concentration of an aqueous solution with a pH of 2.77? (K_w = 1.01 × 10^-14)

A) 5.9 × 10^-12 M
B) 1.7 × 10^-3 M
C) 5.2 × 10^-2 M
D) 1.1 × 10¹ M
E) 5.9 × 10² M

Question 25

An aqueous solution with a pH of 10.60 is diluted from 1.0 L to 2.0 L. What is the pH of the diluted solution?

A) 5.30
B) 9.60
C) 10.30
D) 10.60
E) 10.90

Question 26

The autoionization of pure water, as represented by the equation below, is known to be endothermic (?_r? > 0). Which of the following correctly states what occurs as the temperature of pure water is raised?
H₂O(l) + H₂O(l) $\rightleftharpoons$ H₃O⁺(aq) + OH^-(aq) ?_r? > 0

A) K_w decreases, and the hydronium ion concentration decreases.
B) K_w decreases, and the hydronium ion concentration increases.
C) K_w and the hydronium ion concentration do not change.
D) K_w increases, and the hydronium ion concentration decreases.
E) K_w increases, and the hydronium ion concentration increases.

Question 27

What is the OH^- concentration of an aqueous solution with a pH of 9.83? (K_w = 1.01 × 10^-14)

A) 1.3 × 10^-10 M
B) 6.8 × 10^-5 M
C) 6.8 × 10^-1 M
D) 1.5 × 10^-2 M
E) 7.4 × 10⁹ M

Question 28

What is the pOH of 0.074 M HI(aq) at 25 °C?
(K_w = 1.01 × 10^-14)?

A) 2.60
B) 12.87
C) 11.40
D) 15.13
E) 1.13

Question 29

What volume of water must be added to 14.4 mL of a pH 2.0 solution of HNO₃ in order to change the pH to 4.0?

A) 14.4 mL
B) 143 mL
C) 1.43 × 10³ mL
D) 36 mL
E) 86 mL

Question 30

The pH of a solution at 25 °C in which [OH^-] = 3.9 × 10^-5 M is _____. (K_w = 1.01 × 10^-14)

A) 4.41
B) 3.90
C) 9.59
D) 4.80
E) None of these

Question 31

What is the pH of the final solution when 25 mL of 0.021 M HCl has been added to 35 mL of 0.035 M HCl at 25°C?

A) 3.4
B) 1.9
C) 1.5
D) 2.8
E) 3.5

Question 32

What is the H₃O⁺ concentration in 0.0055 M Ba(OH)₂(aq) at 25 °C? (K_w = 1.01 × 10^-14)?

A) 1.1 × 10^-2 M
B) 5.5 × 10^-3 M
C) 9.1 × 10^-13 M
D) 1.8 × 10^-12 M
E) 1.0 × 10^-7 M

Question 33

Which of the following expressions is not equivalent to the formula of pH?

A) -log [H⁺(aq)]
B) $\log \frac { 1 } { \left[ H ^ { + } ( a q ) \right] }$
C) 14.0 - pOH
D) $- \log \frac { K _ { w } } { \left[ \mathrm { OH } ^ { - } \right] }$
E) -log K_w

Question 34

The concentration of H₃O⁺ in a solution is 5 × 10^-4 M at 25°C. What is its hydroxide-ion concentration? (K_w = 1.01 × 10^-14)

A) 5 × 10^-4 M
B) 2 × 10^-10 M
C) 3 × 10^-10 M
D) 4 × 10^-10 M
E) 2 × 10^-11 M

Question 35

What is the pH of a solution prepared by dissolving 0.523 g of NaOH(s) in 5.50 L of water? (K_w = 1.01 × 10^-14)

A) 1.884
B) 12.116
C) 7.000
D) 11.376
E) 2.624

Question 36

Which of the following is the correct hydronium ion ,H₃O⁺,concentration of 0.0013 M KOH(aq) at 25 °C? (K_w = 1.01 × 10^-14)

A) 7.7 × 10^-12 M
B) 1.3 × 10^-3 M
C) 1.0 × 10^-14 M
D) 1.0 × 10^-7 M
E) 1.3 × 10^-17 M

Question 37

A solution has a hydroxide ion concentration of 0.0040 M. Calculate the pOH of the solution at 25 °C. (K_w = 1.01 × 10^-14)

A) 11.60
B) 2.40
C) 7.00
D) 8.48
E) 5.52

Question 38

What is the pH of a solution prepared by dissolving 0.459 L of HCl(g), measured at STP, in enough water such that the total volume of the solution is 5.50 L? (R = 0.0821 L · atm/K·mol)

A) 2.429
B) 11.571
C) 1.689
D) 7.000
E) 12.311

Question 39

What is the pH of a 0.046 M HClO₄(aq) at 25 °C? (K_w = 1.01 × 10^-14)

A) 15.34
B) 3.08
C) 12.66
D) 1.34
E) 10.92

Question 40

Given the equilibrium constants for the equilibria, H₂O(l) $\rightleftharpoons$ H₃O⁺(aq); K = $5.69 \times 10 ^ { - 10 }$ 2CH₃COOH(aq) + 2H₂O(l) $\rightleftharpoons$ 2CH₃COO?(aq) + 2H₃O⁺(aq); K = $3.06 \times 10 ^ { - 10 }$ determine K_c for the following equilibrium.
CH₃COOH(aq) + NH₃(aq) $\rightleftharpoons$ CH₃COO?(aq) + NH₄⁺(aq)

A) 3.08 × 10⁴
B) 3.25 × 10^-5
C) 9.96 × 10^-15
D) 1.00 × 10¹⁴
E) 1.75 × 10^-5

Question 41

Which acid-base reaction results in acidic solution?

A) HBr(aq) + KOH(aq) ? H₂O( $\ell$ ) + KBr(aq)
B) HNO₃(aq) + LiOH(aq) ? H₂O( $\ell$ ) + LiNO₃(aq)
C) HCl(aq) + KOH(aq) ? H₂O( $\ell$ ) + KCl(aq)
D) H₂SO₄(aq) + CsOH(aq) $\rightleftharpoons$ H₂O( $\ell$ ) + CsHSO₄(aq)
E) HF(aq) + RbOH(aq) $\rightleftharpoons$ H₂O( $\ell$ ) + RbF(aq)

Question 42

Given the following equilibrium constants,
K_a (HSO₄^-) = 1.2 × 10^-2
K_b (CH₃CO₂^-) = 5.6 × 10^-10
K_w = 1.00 × 10^-14
determine the equilibrium constant for the reaction below at 25 °C.
HSO₄^-(aq) + CH₃CO₂^-(aq) $\rightleftharpoons$ SO₄^2-(aq) + CH₃CO₂H(aq)

A) 6.7 × 10^-12
B) 2.1 × 10^-7
C) 1.5 × 10^-3
D) 6.7 × 10²
E) 2.1 × 10⁷

Question 43

The complete reaction of an acid and base is as follows.
HNO₃(aq) + LiOH(aq) ? H₂O( $\ell$ ) + LiNO₃(aq)
What is the equilibrium constant for the net ionic reaction at 25 °C?

A) 1.01 × 10^-14
B) 1.01 × 10^-7
C) 1.01 × 10⁷
D) 1.01 × 10¹⁴
E) more information required

Question 44

Given that K_a for the weak acid HA is 3.49 × 10^-8, calculate K for the reaction of HA with OH^-. HA(aq) + OH?(aq) D A?(aq) + H₂O( $\ell$ )

A) 3.49
B) 3.49 × 10⁶
C) 3.49 × 10^-22
D) 2.87 × 10²¹
E) 2.87 × 10^-7

Question 45

What is K_a at 25°C for the following equilibrium given K_b (CH₃NH₂) = 4.4 × 10^-4 at 25°C.? CH₃NH₃⁺(aq) + H₂O(l) $\rightleftharpoons$ CH₃NH₂(aq) + H₃O⁺(aq)

A) 4.4 × 10^-4
B) 2.3 × 10³
C) 4.4 × 10^-10
D) 4.4 × 10⁴
E) 2.3 × 10^-11

Question 46

Which of the following ionic compounds does not produce a basic aqueous solution at 25 °C?

A) LiCN
B) Na₃PO₄
C) LiNO₂
D) KHSO₃
E) LiCH₃CO₂

Question 47

What is the hydroxide-ion concentration in a solution formed by combining 200. mL of 0.15 M HCl with 300. mL of 0.090 M NaOH at 25°C? HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

A) 1.7 × 10^-13 M
B) 0.090 M
C) 1.7 × 10^-12 M
D) 0.054 M
E) 1.0 × 10^-7 M

Question 48

At 25 °C, all of the following ions produce an acidic solution, except ____.

A) NH₄⁺
B) HSO₃^-
C) HPO₄^2-
D) [Fe(H₂O)₆]³⁺
E) [Al(H₂O)₆]³⁺

Question 49

Aqueous solutions of ammonia (NH₃) and hydrogen cyanide (HCN) react to produce ammonium cyanide, (NH₄CN) according to the following equilibrium reaction. NH3(aq) + HCN(aq) D NH₄⁺(aq) + CN?(aq)
Given the following equilibrium constants, which statement best describes the reaction once equilibrium is established? (K_w = 1.01 × 10^-14)
$$\begin{array} { l l } \mathrm { NH } _ { 4 } ^ { + } & K _ { \mathrm { a } } = 5.6 \times 10 ^ { - 10 } \\\mathrm { HCN } & K _ { \mathrm { a } } = 4.0 \times 10 ^ { - 10 }\end{array}$$

A) The reaction is product favored.
B) The reaction is reactant favored.
C) The reaction is neither product nor reactant favored.

Question 50

What is the equilibrium constant for the following reaction,
HCO₂H(aq) + CN^-(aq) $\rightleftharpoons$ HCO₂^-(aq) + HCN(aq)
And does the reaction favor the formation of reactants or products? The acid dissociation constant, K_a, for HCO₂H is 1.8 × 10^-4 and the acid dissociation constant for HCN is 4.0 × 10^-10.

A) K = 1.00. The reaction favors neither the formation of reactants nor products.
B) K = 2.2 × 10^-6. The reaction favors the formation of products.
C) K = 2.2 × 10^-6. The reaction favors the formation of reactants.
D) K = 4.5 × 10⁵. The reaction favors the formation of products.
E) K = 4.5 × 10⁵. The reaction favors the formation of reactants.

Question 51

Which of the following ionic compounds forms a neutral aqueous solution at 25 °C?

A) NaHSO₃
B) LiClO₃
C) KOCl
D) NH₄F
E) Li₂S

Question 52

Hydrofluoric acid has a pK_a value of 3.14. What is the value of pK_b for fluoride ion?

A) 1.4 × 10^-11
B) 7.2 × 10^-4
C) 3.14
D) 10.86
E) 17.14

Question 53

Given the following acid dissociation constants:
K_a (H₃PO₄) = 7.5 × 10^-3
K_a (NH₄⁺) = 5.6 × 10^-10
Determine the equilibrium constant for the reaction below at 25 °C.
H₃PO₄(aq) + NH₃(aq) $\rightleftharpoons$ NH₄⁺(aq) + H₂PO₄?(aq)

A) 4.2 × 10^-12
B) 7.5 × 10^-8
C) 4.2 × 10²
D) 1.3 × 10⁷
E) 2.4 × 10¹¹

Question 54

Consider the reaction CO₃^2-(aq) + H₂O(l) $\rightleftharpoons$ HCO₃^-(aq) + OH^-(aq). K_b for CO₃^2- is 2.1 × 10^-4 at 25°C. What is K_a for the HCO₃^- ion at 25°C?

A) 4.8 × 10³
B) 4.8 × 10^-11
C) 2.1 × 10^-4
D) 7.2 × 10^-12
E) 9.2 × 10^-8

Question 55

Consider the K_a values for the following acids: Cyanic acid,
HOCN, 3.5 × 10^-4
Formic acid, HCHO₂, 1.7 × 10^-4
Lactic acid, HC₃H₅O₃, 1.3 × 10^-4
Propionic acid, HC₃H₅O₂, 1.3 × 10^-5
Benzoic acid, HC₇H₅O₂, 6.3 × 10^-5
Which of the following is the strongest acid?

A) Cyanic acid
B) Propionic acid
C) Bemzoic acid
D) Formic acid
E) Lactic acid

Question 56

H₃PO₃ is a diprotic weak acid. What is the balanced equilibrium defined as K_b2 of H₃PO₃?

A) H₃PO₃(aq) + H₂O(l) $\rightleftharpoons$ H₃O⁺(aq) + H₂PO₃^-(aq)
B) H₂PO₃^-(aq) + H₂O(l) $\rightleftharpoons$ H₃O⁺(aq) + HPO₃^2-(aq)
C) HPO₃^2-(aq) + H₂O(l) $\rightleftharpoons$ OH^-(l) + H₂PO₃^-(aq)
D) H₂PO₃^-(aq) + H₂O(l) $\rightleftharpoons$ OH^-(l) + H₃PO₃(aq)
E) HPO₃^2-(aq) + H₂O(l) $\rightleftharpoons$ OH^-(aq) + H₃PO₃(aq)

Question 57

What is the hydronium-ion concentration of a 0.25 M solution of HCN (K_a = 4.9 × 10^-10) at 25°C?

A) 1.6 × 10^-4 M
B) 3.3 × 10^-6 M
C) 2.1 × 10^-6 M
D) 1.1 × 10^-5 M
E) 4.4 × 10^-5 M

Question 58

The equilibrium constant, K_a,for a monoprotic acid (benzoic acid) is
6.3 × 10^-5. Which of the following is the correct value of K_b for the benzoate ion, the conjugate base of benzoic acid?

A) 1.6 × 10^-10
B) 6.3 × 10^-5
C) 1.6 × 10⁴
D) 6.3 × 10⁹
E) 6.3 × 10^-19

Question 59

Consider the K_a values for the following acids: Cyanic acid,
HOCN, 3.5 × 10^-4
Formic acid, HCHO₂, 1.7 × 10^-4
Lactic acid, HC₃H₅O₃, 1.3 × 10^-4
Propionic acid, HC₃H₅O₂, 1.3 × 10^-5
Benzoic acid, HC₇H₅O₂, 6.3 × 10^-5
Given initially equimolar solutions of each weak acid, which solution will have the highest pH once equilibrium is established?

A) HOCN
B) HC₇H₅O₂
C) HC₃H₅O₂
D) HC₃H₅O₃
E) HCHO₂

Question 60

Which of the following is the correct hydroxide ion concentration in 0.48 M CH₃CO₂^-(aq)? (K_b of CH₃CO₂^- = 5.6 × 10^-10)

A) 2.7 × 10^-10 M
B) 6.2 × 10^-10 M
C) 1.1 × 10^-5 M
D) 1.6 × 10^-5 M
E) 2.4 × 10^-5 M

Question 61

Which of the following species is the strongest acid in an aqueous solution?

A) CH₃CH₂CO₂H
B) CH₂ClCO₂H
C) CH₃CO₂H
D) CCl₃CO₂H
E) CHCl₂CO₂H

Question 62

What is the pH of a 0.33 M solution of methylamine (CH₃NH₂, K_b = 4.4 × 10^-4) at 25^oC? (K_w = 1.01 × 10^-14)

A) 5.56
B) 0.48
C) 12.07
D) 13.52
E) 1.93

Question 63

Carbonic acid is a diprotic acid, H₂CO₃, with K_a1 = 4.2 × 10^-7 and K_a2 = 4.8 × 10^-11 at 25°C. The ion product for water is K_w = 1.0 × 10^-14 at 25°C. What is the OH^- concentration of a solution that is 0.39 M in Na₂CO₃?

A) 9.0 × 10^-3 M
B) 2.1 × 10^-4 M
C) 9.6 × 10^-5 M
D) 4.3 × 10^-6 M
E) 4.0 × 10^-4 M

Question 64

What is the pH of the solution that results from mixing 75 mL of 0.50 M NH₃(aq) and 75 mL of 0.50 HCl(aq) at 25 °C? (K_b for NH₃ = 1.8 × 10^-5)

A) 0.60
B) 2.67
C) 4.74
D) 4.93
E) 9.26

Question 65

Calculate the pH of a 1.7 M solution of H₂A (K_a1 = 1.0 × 10^-6 and K_a2 is 1.0 × 10^-10).

A) 10.00
B) 2.88
C) 11.12
D) 5.77
E) 7.00

Question 66

Calculate the pH of a 0.09 M solution of ascorbic acid (K_a1 = 7.9 × 10^-5; K_a2 is 1.6 × 10^-12).

A) 11.4
B) 2.6
C) 5.1
D) 8.9
E) 11.8

Question 67

What is the equilibrium pH of an initially 0.83 M solution of the monoprotic acid 3-chloropropanoic acid at 25°C (K_a = $7.8 \times 10 ^ { - 5 }$ )?

A) 2.10
B) 7.00
C) 1.79
D) 12.21
E) 5.21

Question 68

What is the pH of a 0.42 M solution of sodium propionate, NaC₃H₅O₂, at 25°C? (propionic acid, HC₃H₅O₂, is monoprotic and has a K_a = 1.3 × 10^-5 at 25°C.. K_w = 1.01 × 10^-14 )

A) 6.06
B) 4.75
C) 11.10
D) 7.94
E) 9.25

Question 69

What is the equilibrium concentration of H₂C₂O₄ in a 0.170 M oxalic acid, H₂C₂O₄, solution? For oxalic acid, K_a1 = 5.6 × 10^-2 and K_a2 = 5.1 × 10^-5.

A) 9.6 × 10^-2 M
B) 9.8 × 10^-2 M
C) 1.7 × 10^-1 M
D) 5.1 × 10^-5 M
E) 7.4 × 10^-2 M

Question 70

What is the equilibrium hydronium ion concentration of an initially 4.5 M solution of hypoiodous acid, HOI, at 25°C (K_a = $2.3 \times 10 ^ { - 11 }$ )?

A) $1 \times 10 ^ { - 5 }$ M
B) $1 \times 10 ^ { - 7 }$ M
C) $7.2 \times 10 ^{- 6}$ M
D) $1.4 \times 10 ^ { - 5 }$ M
E) $2.26 \times 10 ^{- 6}$ M

Question 71

What is the equilibrium pH of an initially 4.9 M solution of hypoiodous acid, HOI, at 25°C (K_a = $2.3 \times 10 ^ { - 11 }$ ; K_w = 1.01 × 10^-14)?

A) 4.97
B) 7.00
C) 5.12
D) 4.82
E) 8.34

Question 72

Calculate the pH of the following aqueous solution: 0.17 M H₂S (pK_a1 = 7.00; pK_a2 = 12.89)

A) 10.12
B) 6.23
C) 3.88
D) 7.77
E) 7.00

Question 73

What is the equilibrium pH of a 0.700 M solution of H₃PO₄(aq)? (K_a1 = 7.5 × 10^-3, K_a2 = 6.2 × 10^-8, K_a3 = 4.8 × 10^-13)

A) 1.16
B) 3.68
C) 12.32
D) 6.24
E) 7.21

Question 74

What is the hydroxide-ion concentration of a 0.190 M sodium oxalate (Na₂C₂O₄) solution? For oxalic acid (H₂C₂O₄), K_a1 = 5.6 × 10^-2 and K_a2 = 5.1 × 10^-5. (K_w = 1.01 × 10^-14)

A) 6.1 × 10^-6 M
B) 1.0 × 10^-7 M
C) 7.9 × 10^-2 M
D) 3.1 × 10^-3 M
E) 1.8 × 10^-7 M

Question 75

What is the hydroxide-ion concentration in a 0.10 M solution of Na₂CO₃? For carbonic acid, K_a1 = 4.2 × 10^-7 and K_a2 = 4.8 × 10^-11. (K_w = 1.0 × 10^-14)

A) 4.6 × 10^-3 M
B) 2.0 × 10^-4 M
C) 4.9 × 10^-5 M
D) 4.2 × 10^-9 M
E) 2.2 × 10^-6 M

Question 76

What is the pH of the solution which results from mixing 50.0 mL of 0.30 M HF(aq) and 50.0 mL of 0.30 M NaOH(aq) at 25 °C? (K_a of HF = 7.2 × 10^-4)

A) 1.98
B) 5.84
C) 8.16
D) 10.85
E) 12.02

Question 77

The pH of aqueous 0.10 M pyridine (C₅H₅N) ion is 9.09. What is the K_b of this base?

A) 8.0 × 10^-10
B) 1.5 × 10^-9
C) 9.0 × 10^-6
D) 1.6 × 10^-5
E) 1.2 × 10^-5

Question 78

What is the pH of 0.010 M aqueous hypochlorous acid? (K_a of HOCl = 3.5 × 10^-8)

A) 2.00
B) 4.50
C) 4.73
D) 6.54
E) 7.45

Question 79

A 0.10 M solution of a weak monoprotic acid has a hydronium-ion concentration of 8.0 × 10^-4 M. What is the acid-ionization constant, K_a, for this acid?

A) 2.8 × 10^-2
B) 7.5 × 10^-3
C) 8.0 × 10^-4
D) 6.4 × 10^-6
E) 9.6 × 10^-5

Question 80

Which of the following statements is true of the acid-base properties of common cations and anions in aqueous solutions?

A) The anions that are conjugate bases of strong acids are strong bases.
B) The acid-base behavior of anions of polyprotic acids is independent of the extent of deprotonation.
C) Alkali metal and alkali earth cations have no measurable effect on solution pH.
D) Basic anions are conjugate bases of acidic cations.
E) Basic cations are conjugate bases of weak acids.