Question 1

Which of the following aqueous systems has the highest pH?

Accepted Answer

A)   0.1 M HA, pKa = 11.89
B)   0.1 M HMO, pKa = 8.23
C)   0.1 M HA, pKa = 4.55
D)   0.1 M HBO, pKa = 2.43
E)   pure water

Question 2

Given: H2O(aq)  + H2O(l)  2O(aq)  + H2O(l)      H3O+(aq)  + OH-(aq)  H°rxn > 0 When the temperature of a sample of pure water is raised above 25 °C, A)  the hydronium ion concentration will be greater than the hydroxide ion concentration. B)  the hydronium ion concentration will be less than the hydroxide ion concentration. C)  the value of Kw will increase. D)  the hydronium ion concentration could change to 1.0 × 10-10 M. E)  the hydroxide ion concentration could change to 1.0 × 10-10 M." class="answers-bank-image d-inline" rel="preload" >   H3O+(aq)  + OH-(aq)  H°rxn > 0
When the temperature of a sample of pure water is raised above 25 °C,

Accepted Answer

A)   the hydronium ion concentration will be greater than the hydroxide ion concentration.
B)   the hydronium ion concentration will be less than the hydroxide ion concentration.
C)   the value of Kw will increase.
D)   the hydronium ion concentration could change to 1.0 × 10-10 M.
E)   the hydroxide ion concentration could change to 1.0 × 10-10 M.

Question 3

Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. What is the Ka for the acid?

Accepted Answer

A)   0.36
B)   2.4 × 10-2
C)   7.8 × 10-3
D)   1.5 × 10-5
E)   none of the above

Question 4

A 1.25 M solution of the weak acid HA is 9.2% dissociated. What is the pH of the solution?

Accepted Answer

A)   0.64
B)   0.94
C)   1.13
D)   2.16
E)   none of the above

Question 5

Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H3O+] for a 0.20 M solution of picric acid?

Accepted Answer

A)   0.022 M
B)   0.052 M
C)   0.15 M
D)   0.29 M
E)   none of the above

Question 6

What is the value of Kb for the cyanide anion, CN-? Ka(HCN)  = 6.2 × 10-10

Accepted Answer

A)   1.6 × 10-4
B)   1.6 × 10-5
C)   3.8 × 10-4
D)   3.8 × 10-5
E)   6.2 × 104

Question 7

Phosphoric acid, H3PO4, is a triprotic acid, for which Ka1 = 7.2 × 10-3, Ka2 = 6.3 × 10-8 and Ka3 = 4.2 × 10-13. What is the value of Kb for the hydrogen phosphate anion, HPO42-?

Accepted Answer

A)   6.3 × 10-8
B)   4.2 × 10-13
C)   1.4 × 10-12
D)   1.6 × 10-7
E)   2.4 × 10-2

Question 8

Select the correct relationship among the concentrations of species present in a 1.0 M aqueous solution of the weak acid represented by HA.

Accepted Answer

A)   [H2O] > [A-] ~ [H3O+] > [HA] > [OH-]
B)   [H2O] > [HA] > [A-] > [H3O+] > [OH-]
C)   [HA] > [H2O] > [A-] > [H3O+] > [OH-]
D)   [H2O] > [HA] > [A-] ~ [H3O+] > [OH-]
E)   [HA] > [H2O] > [A-] ~ [H3O+] > [OH-]

Question 9

Hydroxylamine, HONH2, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has Kb of 9.1 × 10-9. What is the pH of a 0.025 M HONH2 solution?

Accepted Answer

A)   2.90
B)   4.82
C)   9.18
D)   9.91
E)   11.10

Question 10

Select the pair of substances in which an acid is listed followed by its conjugate base.

Accepted Answer

A)   H+, HCl
B)   NH3, NH4+
C)   HPO42-, H2PO4-
D)   HCO3-, CO32-
E)   CH3COOH, CH3COOH2+

Question 11

What is the pH of a 0.050 M LiOH solution?

Accepted Answer

A)   
B)   1.30
C)   3.00
D)   11.00
E)   12.70

Question 12

The chloride ion, Cl-, is a typical Lewis acid.

Accepted Answer

A) True 
 B)False

Question 13

What is the pH of a 0.20 M HCl solution?

Accepted Answer

A)   
B)   0.70
C)   1.61
D)   12.39
E)   13.30

Question 14

The substance NH3 is considered

Accepted Answer

A)   a weak acid.
B)   a weak base.
C)   a strong acid.
D)   a strong base.
E)   a neutral compound.

Question 15

Define an acid according to the Lewis theory. Write a balanced equation in support of this definition, in which the acid is neither an Arrhenius acid nor a Brønsted-Lowry acid.

Accepted Answer

According to Lewis, an acid is...

Question 16

What is the pH of a 0.0035 M KOH solution?

Accepted Answer

A)   2.46
B)   5.65
C)   8.35
D)   11.54
E)   none of the above

Question 17

All Lewis acids contain at least one proton.

Accepted Answer

A) True 
 B)False

Question 18

Select the pair of substances which is not a conjugate acid-base pair.

Accepted Answer

A)   H3O+, H2O
B)   HNO2, NO2-
C)   H2SO4, HSO4-
D)   H2S, S2-
E)   NH3, NH2-

Question 19

Farmers who raise cotton once used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 × 10-4, K2 = 5.6 × 10-8, and K3 = 3 × 10-13. What is the pH of a 0.500 M solution of arsenic acid?

Accepted Answer

A)   0.85
B)   1.96
C)   3.90
D)   4.51
E)   none of the above

Question 20

In order to be a Brønsted-Lowry base, a species must contain a proton.

Accepted Answer

A) True 
 B)False

Exam 18: Acid-Base Equilibria

All Lewis acids contain at least one proton.

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Select the correct relationship among the concentrations of species present in a 1.0 M aqueous solution of the weak acid represented by HA.

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Which of the following aqueous systems has the highest pH?

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What is the pH of a 0.0035 M KOH solution?

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Select the pair of substances which is not a conjugate acid-base pair.

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Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H3O+] for a 0.20 M solution of picric acid?

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Hydroxylamine, HONH2, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has Kb of 9.1 × 10-9. What is the pH of a 0.025 M HONH2 solution?

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In order to be a Brønsted-Lowry base, a species must contain a proton.

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What is the pH of a 0.20 M HCl solution?

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Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. What is the Ka for the acid?

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What is the value of Kb for the cyanide anion, CN-? Ka(HCN) = 6.2 × 10-10

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Given: H2O(aq) + H2O(l) H3O+(aq) + OH-(aq) H°rxn > 0 When the temperature of a sample of pure water is raised above 25 °C,

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A 1.25 M solution of the weak acid HA is 9.2% dissociated. What is the pH of the solution?

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Define an acid according to the Lewis theory. Write a balanced equation in support of this definition, in which the acid is neither an Arrhenius acid nor a Brønsted-Lowry acid.

Correct AnswerverifiedAccording to Lewis, an acid is...View AnswerShow Answer

The substance NH3 is considered

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The chloride ion, Cl-, is a typical Lewis acid.

Correct AnswerverifiedShow Answer

Farmers who raise cotton once used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 × 10-4, K2 = 5.6 × 10-8, and K3 = 3 × 10-13. What is the pH of a 0.500 M solution of arsenic acid?

Correct AnswerverifiedShow Answer

Phosphoric acid, H3PO4, is a triprotic acid, for which Ka1 = 7.2 × 10-3, Ka2 = 6.3 × 10-8 and Ka3 = 4.2 × 10-13. What is the value of Kb for the hydrogen phosphate anion, HPO42-?

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What is the pH of a 0.050 M LiOH solution?

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Select the pair of substances in which an acid is listed followed by its conjugate base.

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Picric acid has been used in the leather industry and in etching copper. However, its laboratory use has been restricted because it dehydrates on standing and can become shock sensitive. It has an acid dissociation constant of 0.42. What is the [H₃O⁺] for a 0.20 M solution of picric acid?

Correct Answer
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Hydroxylamine, HONH₂, readily forms salts such as hydroxylamine hydrochloride which are used as antioxidants in soaps. Hydroxylamine has K_b of 9.1 × 10^-9. What is the pH of a 0.025 M HONH₂solution?

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Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. What is the K_a for the acid?

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What is the value of K_b for the cyanide anion, CN^-? K_a(HCN) = 6.2 × 10^-10

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Given: H₂O(aq) + H₂O(l) H₃O⁺(aq) + OH^-(aq) H°_rxn > 0 When the temperature of a sample of pure water is raised above 25 °C,

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According to Lewis, an acid is...
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The substance NH₃is considered

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The chloride ion, Cl^-, is a typical Lewis acid.

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Farmers who raise cotton once used arsenic acid, H₃AsO₄, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K₁= 2.5 × 10^-4, K₂= 5.6 × 10^-8, and K₃= 3 × 10^-13. What is the pH of a 0.500 M solution of arsenic acid?

Correct Answer
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Phosphoric acid, H₃PO₄, is a triprotic acid, for which K_a1 = 7.2 × 10^-3, K_a2 = 6.3 × 10^-8 and K_a3= 4.2 × 10^-13. What is the value of K_b for the hydrogen phosphate anion, HPO₄^2-?

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