Deck 17: The Chemistry of Acids and Bases

Question 1

Which are the Brønsted-Lowry acids in the following equilibrium?
CH₃COO^-(aq)+ H₂O(l) 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

Answer 1

H₂O and CH₃COOH

Question 2

According to the Brønsted-Lowry definition,an acid

A) increases the H₃O⁺ 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.

Answer 2

is a proton donor.

Question 3

Which of the following statements is/are consistent with the Brønsted-Lowry concept of acids and bases?
1)A conjugate acid-base pair may differ by only one proton.
2)A Brønsted-Lowry base is defined as a hydroxide ion donor.
3)Brønsted-Lowry acid-base reactions are restricted to aqueous solutions.

A) 1 only
B) 2 only
C) 3 only
D) 1 and 2
E) 1,2,and 3

Answer 3

1 only

Question 4

Which is NOT an amphiprotic species in water?

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

Question 5

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 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

Which of the following species is amphiprotic in aqueous solution?

A) NH₄⁺
B) H₃O⁺
C) HCl
D) CN^-
E) H₂O

Question 8

The autoionization of pure water,as represented by the equation below,is known to be endothermic ( $\Delta$ _rH > 0.Which of the following correctly states what occurs as the temperature of pure water is raised?
H₂O(l)+ H₂O(l) H₃O⁺(aq)+ OH^-(aq) $\Delta$ _rH > 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 9

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

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

Question 10

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

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

Question 11

What is the conjugate $\underline{\text{ base }}$ of HPO₄^2-in aqueous solution?

A) not possible
B) PO₄^3-
C) HPO₄^2-
D) H₂PO₄^2-
E) H₃PO₄

Question 12

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

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

Question 13

In the following reaction,
HCO₃^-(aq)+ H₂O( ) 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.

Question 14

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 15

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 16

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

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

Question 17

At 50°C the autoionization constant for pure water,K_w,is .What is the H₃O⁺ concentration in pure water at 50°C?

A) M
B) 1.01 $\times$ 10^-7 M
C) M
D) M
E) 1.01 $\times$ 10^-14 M

Question 18

Which of the following expressions is not equivalent to pH?

A) -log [H⁺(aq)]
B)
C) 14.0 - pOH
D)
E) -log K_w

Question 19

What volume of water must be added to 14.8 mL of a pH 2.0 solution of HNO₃ in order to change the pH to 4.0?

A) 14.8 mL
B) 147 mL
C) 1.47 $\times$ 10³ mL
D) 37 mL
E) 85 mL

Question 20

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

A) NH₃(aq)+ H₂O(l) NH₄⁺(aq)+ OH^-(aq)
B) NH₃(aq)+ H₂O(l) NH₂^-(aq)+ H₃O⁺(aq)
C) NH₃(aq)+ H₃O⁺(aq) NH₄⁺(aq)+ H₂O(l)
D) NH₃(aq)+ OH^-(aq) NH₂^-(aq)+ H₂O(l)
E) NH₃(aq)+ H₂O(l) NH₂^-(aq)+ H₃O⁺(aq)

Question 21

What is the pOH of 0.067 M HI(aq)at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)?

A) 2.70
B) 12.83
C) 11.30
D) 15.17
E) 1.17

Question 22

What is the hydroxide-ion concentration in a solution formed by combining 200.mL of 0.15 M HCl with 300.mL of 0.091 M NaOH at 25°C?
HCl(aq)+ NaOH(aq) $\to$ NaCl(aq)+ H₂O(l)

A) 1.7 $\times$ 10^-13 M
B) 0.091 M
C) 1.9 $\times$ 10^-12 M
D) 0.055 M
E) 1.0 $\times$ 10^-7 M

Question 23

The H₃O⁺ concentration of a solution is 2.5 $\times$ 10^-6 M.What is the pH of the solution?

A) 6.81
B) 3.77
C) 2.00
D) 5.60
E) 10.60

Question 24

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

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

Question 25

What is the pH of a solution prepared by dissolving 0.581 L of HCl(g),measured at STP,in enough water such that the total volume of the solution is 2.00 L? (R = 0.0821 L · atm/K·mol)

A) 1.887
B) 12.113
C) 1.586
D) 7.000
E) 12.414

Question 26

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

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

Question 27

Which one of the following aqueous solutions will have a pH of 2.00 at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 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 28

A solution has a hydroxide-ion concentration of 0.0030 M.What is the pOH of the solution at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)

A) 11.48
B) 2.52
C) 7.00
D) 8.19
E) 5.81

Question 29

What is the H₃O⁺ concentration in 0.0042 M Ba(OH)₂(aq)at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)?

A) 8.4 $\times$ 10^-3 M
B) 4.2 $\times$ 10^-3 M
C) 1.2 $\times$ 10^-12 M
D) 2.4 $\times$ 10^-12 M
E) 1.0 $\times$ 10^-7 M

Question 30

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

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

Question 31

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

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

Question 32

What is the pH of a 0.016 M HClO₄(aq)at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)

A) 15.80
B) 4.14
C) 12.20
D) 1.80
E) 9.86

Question 33

What is the pH of a solution prepared by dissolving 0.923 g of NaOH(s)in 5.50 L of water? (K_w = 1.01 $\times$ 10^-14)

A) 1.637
B) 12.363
C) 7.000
D) 11.623
E) 2.377

Question 34

The concentration of H₃O⁺ in a solution is 7 $\times$ 10^-4 M at 25°C.What is its hydroxide-ion concentration? (K_w = 1.01 $\times$ 10^-14)

A) 7 $\times$ 10^-4 M
B) 1 $\times$ 10^-10 M
C) 2 $\times$ 10^-10 M
D) 3 $\times$ 10^-10 M
E) 1 $\times$ 10^-11 M

Question 35

What is the H₃O⁺ concentration in 0.0047 M NaOH(aq)at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)

A) 2.1 $\times$ 10^-12 M
B) 4.7 $\times$ 10^-3 M
C) 1.0 $\times$ 10^-14 M
D) 1.0 $\times$ 10^-7 M
E) 4.7 $\times$ 10^-17 M

Question 36

What is the OH^- concentration of an aqueous solution with a pH of 2.77? (K_w = 1.01 $\times$ 10^-14)

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

Question 37

What is the H₃O⁺ concentration of 0.0017 M NaOH(aq)at 25 ^$\circ$ C? (K_w = 1.01 $\times$ 10^-14)

A) 5.9 $\times$ 10^-12 M
B) 1.7 $\times$ 10^-3 M
C) 1.0 $\times$ 10^-14 M
D) 1.0 $\times$ 10^-7 M
E) 1.7 $\times$ 10^-17 M

Question 38

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) $\to$ NaCl(aq)+ H₂O(l)

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

Question 39

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 40

What is the pH of the final solution when 25 mL of 0.021 M HCl has been added to 35 mL of 0.036 M HCl at 25°C?

A) 3.3
B) 1.9
C) 1.5
D) 2.7
E) 3.5

Question 41

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

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

Question 42

The K_a for the monoprotic acid hypochlorous acid is 3.5 $\times$ 10^-8.What is K_b for the hypochlorite ion,the conjugate base of hypochlorous acid?

A) 2.9 $\times$ 10^-7
B) 3.5 $\times$ 10^-8
C) 2.9 $\times$ 10⁷
D) 3.5 $\times$ 10⁶
E) 3.5 $\times$ 10^-22

Question 43

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

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

Question 44

What is the equilibrium pH of an initially 0.64 M solution of the monoprotic acid benzoic acid at 25°C (K_a = )?

A) 2.20
B) 7.00
C) 1.90
D) 12.10
E) 5.10

Question 45

Consider the K_a values for the following acids:
Cyanic acid,HOCN,3.5 $\times$ 10^-4
Formic acid,HCHO₂,1.7 $\times$ 10^-4
Lactic acid,HC₃H₅O₃,1.3 $\times$ 10^-4
Propionic acid,HC₃H₅O₂,1.3 $\times$ 10^-5
Benzoic acid,HC₇H₅O₂,6.3 $\times$ 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 46

What is the equilibrium constant for the following reaction,
HCO₂H(aq)+ CN^-(aq) 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 $\times$ 10^-4 and the acid dissociation constant for HCN is 4.0 $\times$ 10^-10.

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

Question 47

Which ionic compound forms a pH-neutral aqueous solution at 25 ^$\circ$ C?

A) KHCO₃
B) LiCl
C) KOCl
D) NH₄Cl
E) K₂S

Question 48

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) $\leftrightarrows$ NH₄⁺(aq)+ CN^-(aq)
Given the following equilibrium constants,which statement best describes the reaction once equilibrium is established? (K_w = 1.01 $\times$ 10^-14)
NH₄⁺ $~~~~~~~~$ K_a = 5.6 $\times$ 10^-10
HCN $~~~~~~~~$$~ ~$ K_a = 4.0 $\times$ 10^-10

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

Question 49

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

A) 4.4 $\times$ 10^-4
B) 2.3 $\times$ 10³
C) 4.4 $\times$ 10^-10
D) 4.4 $\times$ 10⁴
E) 2.3 $\times$ 10^-11

Question 50

Consider the K_a values for the following acids:
Cyanic acid,HOCN,3.5 $\times$ 10^-4
Formic acid,HCHO₂,1.7 $\times$ 10^-4
Lactic acid,HC₃H₅O₃,1.3 $\times$ 10^-4
Propionic acid,HC₃H₅O₂,1.3 $\times$ 10^-5
Benzoic acid,HC₇H₅O₂,6.3 $\times$ 10^-5
Which has the strongest conjugate base?

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

Question 51

What is the OH^- concentration in 0.48 M CH₃CO₂^-(aq)? (K_b of CH₃CO₂^- = 5.6 $\times$ 10^-10)

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

Question 52

The complete reaction of an acid and base is as follows.HClO₄(aq)+ LiOH(aq) $\to$ H₂O( )+ LiClO₄(aq)
What is the equilibrium constant for the net ionic reaction at 25 ^$\circ$ C?

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

Question 53

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

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

Question 54

At 25 ^$\circ$ 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 55

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

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

Question 56

At 25 ^$\circ$ C,all of the following ionic compounds produce a basic aqueous solution,except ____.

A) KSH
B) Na₃PO₄
C) LiNO₂
D) KHSO₃
E) KCH₃CO₂

Question 57

What is the equilibrium hydronium ion concentration of an initially 5.4 M solution of hypochlorous acid,HOCl,at 25°C (K_a = )?

A) M
B) M
C) M
D) M
E) M

Question 58

Which acid-base reaction results in an acidic solution?

A) HNO₃(aq)+ CsOH(aq) $\to$ H₂O( )+ CsNO₃(aq)
B) HI(aq)+ LiOH(aq) $\to$ H₂O( )+ LiI(aq)
C) HBr(aq)+ NaOH(aq) $\to$ H₂O( )+ NaBr(aq)
D) H₂SO₃(aq)+ LiOH(aq) H₂O( )+ LiHSO₃(aq)
E) HF(aq)+ LiOH(aq) H₂O( )+ LiF(aq)

Question 59

Given that K_a for the weak acid HA is 3.46 $\times$ 10^-8,calculate K for the reaction of HA with OH^-.HA(aq)+ OH^-(aq). A^-(aq)+ H₂O( )

A) 3.46
B) 3.46 $\times$ 10⁶
C) 3.46 $\times$ 10^-22
D) 2.89 $\times$ 10²¹
E) 2.89 $\times$ 10^-7

Question 60

Given the equilibrium constants for the equilibria,

Determine K_c for the following equilibrium.

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

Question 61

What is the hydroxide-ion concentration of a 0.250 M sodium oxalate (Na₂C₂O₄)solution? For oxalic acid (H₂C₂O₄),K_a1 = 5.6 $\times$ 10^-2 and K_a2 = 5.1 $\times$ 10^-5.(K_w = 1.01 $\times$ 10^-14)

A) 7.0 $\times$ 10^-6 M
B) 1.0 $\times$ 10^-7 M
C) 9.4 $\times$ 10^-2 M
D) 3.5 $\times$ 10^-3 M
E) 2.1 $\times$ 10^-7 M

Question 62

Calculate the pH of a 0.04 M solution of ascorbic acid (K_a1 = 7.9 $\times$ 10^-5; K_a2 is 1.6 $\times$ 10^-12).

A) 11.2
B) 2.8
C) 5.5
D) 8.5
E) 11.8

Question 63

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 ^$\circ$ C? (K_a of HF = 7.2 $\times$ 10^-4)

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

Question 64

All of the following compounds are acids containing chlorine.Which compound is the weakest acid?

A) HCl
B) HClO
C) HClO₂
D) HClO₃
E) HClO₄

Question 65

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

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

Question 66

A 0.10 M solution of a weak monoprotic acid has a hydronium-ion concentration of 4.6 $\times$ 10^-4 M.What is the acid-ionization constant,K_a,for this acid?

A) 2.1 $\times$ 10^-2
B) 3.2 $\times$ 10^-3
C) 4.6 $\times$ 10^-4
D) 2.1 $\times$ 10^-6
E) 5.5 $\times$ 10^-5

Question 67

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

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

Question 68

Rank the following in order of decreasing acid strength in aqueous solution: HCl,HOCl,HOBr,HOI.

A) HCl > HClO > HBrO > HIO
B) HIO > HBrO > HClO > HCl
C) HCl > HIO > HBrO > HClO
D) HClO > HCl > HBrO > HIO
E) HClO > HBrO > HCl > HIO

Question 69

Which of the following statements is INCORRECT?

A) H₃PO₄ is a stronger acid than H₂PO₄^-.
B) HClO₃ is a stronger acid than HClO₂.
C) HNO₃ is a stronger acid than HNO₂.
D) [Fe(H₂O)₆]²⁺ is a stronger acid than [Fe(H₂O)₆]³⁺.
E) HOCl is stronger acid than HOBr.

Question 70

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

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

Question 71

What is the equilibrium pH of a 0.835 M solution of H₃PO₄(aq)? (K_a1 = 7.5 $\times$ 10^-3,K_a2 = 6.2 $\times$ 10^-8,K_a3 = 4.8 $\times$ 10^-13)

A) 1.12
B) 3.64
C) 12.32
D) 6.20
E) 7.21

Question 72

What is the equilibrium pOH of an initially 5.4 M solution of hypochlorous acid,HOCl,at 25°C (K_a = ; K_w = 1.01 $\times$ 10^-14)?

A) 10.60
B) 7.42
C) 10.45
D) 10.76
E) 4.13

Question 73

The pH of a solution of 2.2 M H₂A (K_a1 = 1.0 $\times$ 10^-6 and K_a2 is 1.0 $\times$ 10^-10)is:

A) 10.00
B) 2.83
C) 11.17
D) 5.66
E) 7.00

Question 74

What is the hydroxide-ion concentration in a 0.22 M solution of Na₂CO₃? For carbonic acid,K_a1 = 4.2 $\times$ 10^-7 and K_a2 = 4.8 $\times$ 10^-11.(K_w = 1.0 $\times$ 10^-14)

A) 6.8 $\times$ 10^-3 M
B) 2.0 $\times$ 10^-4 M
C) 7.2 $\times$ 10^-5 M
D) 4.2 $\times$ 10^-9 M
E) 3.2 $\times$ 10^-6 M

Question 75

What is the equilibrium concentration of H₂C₂O₄ in a 0.230 M oxalic acid,H₂C₂O₄,solution? For oxalic acid,K_a1 = 5.6 $\times$ 10^-2 and K_a2 = 5.1 $\times$ 10^-5.

A) 1.4 $\times$ 10^-1 M
B) 1.1 $\times$ 10^-1 M
C) 2.3 $\times$ 10^-1 M
D) 5.1 $\times$ 10^-5 M
E) 8.9 $\times$ 10^-2 M

Question 76

Calculate the pH of the following aqueous solution:
0)29 M H₂S (pK_a1 = 7.00; pK_a2 = 12.89)

A) 10.23
B) 6.46
C) 3.77
D) 7.54
E) 7.00

Question 77

Carbonic acid is a diprotic acid,H₂CO₃,with K_a1 = 4.2 $\times$ 10^-7 and K_a2 = 4.8 $\times$ 10^-11 at 25°C.The ion product for water is K_w = 1.0 $\times$ 10^-14 at 25°C.What is the OH^- concentration of a solution that is 0.18 M in Na₂CO₃?

A) 6.1 $\times$ 10^-3 M
B) 2.1 $\times$ 10^-4 M
C) 6.5 $\times$ 10^-5 M
D) 2.9 $\times$ 10^-6 M
E) 2.7 $\times$ 10^-4 M

Question 78

What is the pH of the solution which results from mixing 75 mL of 0.50 M NH₃(aq)and 75 mL of 0.50 HCl(aq)at 25 ^$\circ$ C? (K_b for NH₃ = 1.8 $\times$ 10^-5)

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

Question 79

What is the pH of a 0.11 M solution of methylamine (CH₃NH₂,K_b = 4.4 $\times$ 10^-4)at 25^oC? (K_w = 1.01 $\times$ 10^-14)

A) 5.80
B) 0.96
C) 11.83
D) 13.04
E) 2.17

Question 80

What is the pH of a 0.28 M solution of sodium propionate,NaC₃H₅O₂,at 25°C? (propionic acid,HC₃H₅O₂,is monoprotic and has a K_a = 1.3 $\times$ 10^-5 at 25°C..K_w = 1.01 $\times$ 10^-14 )

A) 6.26
B) 4.83
C) 11.10
D) 7.74
E) 9.17