Question 1

Ammonia is a .

Accepted Answer

A)   weak acid
B)   strong acid
C)   strong base
D)   salt
E)   weak base

Question 2

HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0 °C. The Ka of HZ is .

Accepted Answer

A)   1.4 × 10- 10
B)   2.8 × 10- 12
C)   1.2 × 10- 5
D)   9.9 × 10- 2
E)   6.9 × 10- 9

Question 3

Ka for HCN is 4.9 × 10- 10. What is the pH of a 0.068 M aqueous solution of sodium cyanide?

Accepted Answer

A)   0.74
B)   2.9
C)   7.0
D)   13
E)   11

Question 4

The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0 °C is 4.48. What is the value of Ka for HBrO?

Accepted Answer

A)   3.3 × 10- 5 
B)   6.0 × 10- 5 
C)   1.1 × 10- 9 
D)   3.0 × 104 
E)   2.0 × 10- 9

Question 5

A 0.15 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 5.35. The value of Ka for HA is .

Accepted Answer

A)   7.1 × 10- 9
B)   1.4 × 10- 10
C)   3.3 × 104
D)   3.0 × 10- 5
E)   1.8 × 10- 5

Question 6

What is the pH of an aqueous solution at 25.0 °C in which [H+] is 0.00250 M?

Accepted Answer

A)   3.40
B)   2.60
C)   - 2.60
D)   2.25
E)   - 3.40

Question 7

A solution of formic acid is 3.0% dissociated at 25.0 oC. What is the original concentration (in M) of the formic acid solution? The Ka at 25.0 oC for formic acid is 1.8 × 10- 4.

Accepted Answer

Question 8

What is the conjugate acid of NH3?

Accepted Answer

A)   NH3+ 
B)   NH4OH
C)   NH3 
D)   NH4+ 
E)   NH2+

Question 9

Calculate the pH of 0.726 M anilinium hydrochloride (C6H5NH3Cl)  solution in water, given that Kb for aniline is 3.83 × 10- 4.

Accepted Answer

A)   12.2
B)   12.4
C)   5.36
D)   8.64
E)   1.77

Question 10

The molar concentration of hydronium ion in pure water at 25°C is .

Accepted Answer

A)   1.00
B)   1.0 × 10- 14
C)   0.00
D)   7.00
E)   1.0 × 10- 7

Question 11

An aqueous solution contains 0.10 M NaOH. The solution is _.

Accepted Answer

A)   highly colored
B)   basic
C)   acidic
D)   very dilute
E)   neutral

Question 12

The base- dissociation constant of ethylamine (C2H5NH2)  is 6.4 × 10- 4 at 25.0 °C. The of [H+] in a 1.6 × 10- 2 M solution of ethylamine is M.

Accepted Answer

A)   3.2 × 10- 3
B)   2.9 × 10- 3
C)   11.46
D)   3.1 × 10- 12
E)   3.5 × 10- 12

Question 13

The acid- dissociation constants of phosphoric acid (H3PO4)  are Ka1 = 7.5 × 10- 3, Ka2 = 6.2 × 10- 8, and Ka3 = 4.2 × 10- 13 at 25.0 °C. What is the molar concentration of phosphate ion in a 2.5 M aqueous solution of phosphoric acid?

Accepted Answer

A)   0.13
B)   2.5 × 10- 5
C)   2.0 × 10- 19
D)   9.1 × 10- 5
E)   8.2 × 10- 9

Question 14

Which one of the following is the weakest acid?

Accepted Answer

A)   HCN (Ka = 4.9 × 10- 10) 
B)   Acetic acid (Ka = 1.8 × 10- 5) 
C)   HF (Ka = 6.8 × 10- 4) 
D)   HNO2 (Ka = 4.5 × 10- 4) 
E)   HClO (Ka = 3.0 × 10- 8)

Question 15

According to the Arrhenius concept, an acid is a substance that .

Accepted Answer

A)   causes an increase in the concentration of H+ in aqueous solutions
B)   tastes bitter
C)   can accept a pair of electrons to form a coordinate covalent bond
D)   is capable of donating one or more H+
E)   reacts with the solvent to form the cation formed by autoionization of that solvent

Question 16

The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO)  is 3.0 × 10- 8. At equilibrium, the molarity of H3O+ in a 0.010 M solution of HClO is .

Accepted Answer

A)   2.00
B)   0.010
C)   1.7 × 10- 5
D)   5.8 × 10- 10
E)   4.76

Question 17

A 0.0035- M aqueous solution of a particular compound has pH = 2.46. The compound is
)

Accepted Answer

A)   a weak acid
B)   a strong base
C)   a salt
D)   a strong acid
E)   a weak base

Question 18

A 7.0 × 10- 3 M aqueous solution of Ca(OH) 2 at 25.0 °C has a pH of .

Accepted Answer

A)   1.4 × 10- 2
B)   12.15
C)   7.1 × 10- 13
D)   11.85
E)   1.85

Question 19

A substance that is capable of acting as both an acid and as a base is .

Accepted Answer

A)   conjugated
B)   amphoteric
C)   miscible
D)   autosomal
E)   saturated

Question 20

Ka for HX is 7.5 × 10- 12. What is the pH of a 0.15 M aqueous solution of NaX?

Accepted Answer

A)   8.0
B)   12
C)   7.9
D)   6.0
E)   1.9

Exam 16: Acid-Base Equilibria

A 0.15 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 5.35. The value of Ka for HA is .

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Calculate the pH of 0.726 M anilinium hydrochloride (C6H5NH3Cl) solution in water, given that Kb for aniline is 3.83 × 10- 4.

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The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10- 8. At equilibrium, the molarity of H3O+ in a 0.010 M solution of HClO is .

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A solution of formic acid is 3.0% dissociated at 25.0 oC. What is the original concentration (in M) of the formic acid solution? The Ka at 25.0 oC for formic acid is 1.8 × 10- 4.

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Ka for HX is 7.5 × 10- 12. What is the pH of a 0.15 M aqueous solution of NaX?

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The base- dissociation constant of ethylamine (C2H5NH2) is 6.4 × 10- 4 at 25.0 °C. The of [H+] in a 1.6 × 10- 2 M solution of ethylamine is M.

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Ka for HCN is 4.9 × 10- 10. What is the pH of a 0.068 M aqueous solution of sodium cyanide?

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What is the pH of an aqueous solution at 25.0 °C in which [H+] is 0.00250 M?

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HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0 °C. The Ka of HZ is .

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What is the conjugate acid of NH3?

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Ammonia is a .

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Which one of the following is the weakest acid?

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An aqueous solution contains 0.10 M NaOH. The solution is _.

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The acid- dissociation constants of phosphoric acid (H3PO4) are Ka1 = 7.5 × 10- 3, Ka2 = 6.2 × 10- 8, and Ka3 = 4.2 × 10- 13 at 25.0 °C. What is the molar concentration of phosphate ion in a 2.5 M aqueous solution of phosphoric acid?

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A substance that is capable of acting as both an acid and as a base is .

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A 0.0035- M aqueous solution of a particular compound has pH = 2.46. The compound is )

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A 7.0 × 10- 3 M aqueous solution of Ca(OH) 2 at 25.0 °C has a pH of .

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According to the Arrhenius concept, an acid is a substance that .

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The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0 °C is 4.48. What is the value of Ka for HBrO?

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The molar concentration of hydronium ion in pure water at 25°C is .

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A 0.15 M aqueous solution of the weak acid HA at 25.0 °C has a pH of 5.35. The value of K_afor HA is .

Correct Answer
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Calculate the pH of 0.726 M anilinium hydrochloride (C₆H₅NH₃Cl) solution in water, given that K_bfor aniline is 3.83 × 10^-⁴.

Correct Answer
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The acid- dissociation constant at 25.0 °C for hypochlorous acid (HClO) is 3.0 × 10^-⁸. At equilibrium, the molarity of H₃O⁺in a 0.010 M solution of HClO is .

Correct Answer
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A solution of formic acid is 3.0% dissociated at 25.0 ^oC. What is the original concentration (in M) of the formic acid solution? The K_aat 25.0 ^oC for formic acid is 1.8 × 10^-⁴.

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K_afor HX is 7.5 × 10^-¹². What is the pH of a 0.15 M aqueous solution of NaX?

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The base- dissociation constant of ethylamine (C₂H₅NH₂) is 6.4 × 10^-⁴at 25.0 °C. The of [H⁺] in a 1.6 × 10^-²M solution of ethylamine is M.

Correct Answer
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K_afor HCN is 4.9 × 10^-¹⁰. What is the pH of a 0.068 M aqueous solution of sodium cyanide?

Correct Answer
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What is the pH of an aqueous solution at 25.0 °C in which [H⁺] is 0.00250 M?

Correct Answer
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HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0 °C. The K_aof HZ is .

Correct Answer
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What is the conjugate acid of NH₃?

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The acid- dissociation constants of phosphoric acid (H₃PO₄) are K_a1= 7.5 × 10^-³, K_a2= 6.2 × 10^-⁸, and K_a3= 4.2 × 10^-¹³at 25.0 °C. What is the molar concentration of phosphate ion in a 2.5 M aqueous solution of phosphoric acid?

Correct Answer
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A 7.0 × 10^-³M aqueous solution of Ca(OH) ₂at 25.0 °C has a pH of .

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The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0 °C is 4.48. What is the value of K_afor HBrO?

Correct Answer
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