Deck 16: Aqueous Acidbase Equilibriums

Question 1

In Brønsted-Lowry terms, a base is any substance that can donate a proton.

Answer 1

False

Question 2

Which of the following solutions is basic?

A) [H⁺] = 6.2 × 10^-6
B) [H⁺] = 9.3 × 10^-5
C) [H⁺] = 2.2 × 10^-8
D) [H⁺] = 8.5 × 10^-4
E) [H⁺] = 1.0 × 10^-7

Answer 2

[H⁺] = 2.2 × 10^-8

Question 3

Which of the following solutions is acidic?

A) $\left[ \mathrm { H } ^ { + } \right] = 4.5 \times 10 ^ { - 9 }$
B) $\left[ \mathrm { H } ^ { + } \right] = 2.6 \times 10 ^ { - 5 }$
C) $\left[ \mathrm { H } ^ { + } \right] = 3.8 \times 10 ^ { - 8 }$
D) $\left[ \mathrm { H } ^ { + } \right] = 8.5 \times 10 ^ { - 9 }$
E) $\left[ \mathrm { H } ^ { + } \right] = 6.6 \times 10 ^ { - 12 }$

Answer 3

$\left[ \mathrm { H } ^ { + } \right] = 2.6 \times 10 ^ { - 5 }$

Question 4

State the variation in pH in acidic, basic, and neutral solutions.

Question 5

Which of the following is true of a base?

A) It is a substance that dissociates in water to produce $\mathrm { H } ^ { + }$ ions.
B) It has a pH value lesser than 7.
C) It is an electron-pair acceptor.
D) It is any substance that can donate a proton.
E) It usually has one or more lone pairs of electrons.

Question 6

If the pOH of a solution is 8.53, what is its [OH^-] ion concentration?

A) 6.26×10^-8
B) 3.85×10^-10
C) 9.23×10^-8
D) 1.44×10^-7
E) 2.95×10^-9

Question 7

What is the pOH of a solution if its $\left[ \mathrm { OH } ^ { - } \right]$ concentration is $6.2 \times 10 ^ { - 3 }$ ?

A) 8.8
B) 7.3
C) 2.2
D) 4.6
E) 5.8

Question 8

Which of the following is true of an acid?

A) It is a substance that dissociates in water to produce hydroxide ions.
B) It always has a corresponding conjugate base with one fewer proton.
C) It is any substance that can accept a proton.
D) It is an electron-pair donor.
E) It has a pH value greater than 7.

Question 9

If the pK_w for water at $65 ^ { \circ } \mathrm { C }$ is 10.4, the K_w at the same temperature is _____.

A) 3.26 × 10^-13
B) 6.83 × 10^-11
C) 3.97 × 10^-13
D) 4.00 × 10^-11
E) 8.82 × 10^-12

Question 10

In pure water, the concentrations of the hydronium ion and the hydroxide ion are equal.

Question 11

An acid-base reaction involves the reaction of a proton with a hydroxide ion to form _____.

Question 12

What is the pH of water, if its [ $\mathrm { H } _ { 3 } \mathrm { O } ^ { + }$ ] concentration is 3.00 × $10 ^ { - 3 }$ ?

A) 4.07
B) 7.04
C) 5.53
D) 2.52
E) 3.01

Question 13

The ion-product constant of liquid water ( $K _ { w }$ ) remains constant irrespective of the change in temperature.

Question 14

If the pH of a solution is equal to 4.76, the solution's [H⁺] ion concentration is _____.

A) 3.65 × 10^-6 M
B) 8.94 × 10^-5 M
C) 6.36 × 10^-5 M
D) 1.32 × 10^-6 M
E) 1.74 × 10^-5 M

Question 15

If the $\mathrm { p } K _ { w }$ of a neutral solution is 13.6, what is its pH?

A) 3.69
B) 4.54
C) 13.6
D) 6.81
E) 2.38

Question 16

If the $K _ { w }$ for water at $80 ^ { \circ } \mathrm { C }$ is $5.60 \times 10 ^ { - 11 }$ , the $\mathrm { p } K _ { w }$ for water at the same temperature is _____.

A) 12.8
B) 10.3
C) 13.9
D) 9.80
E) 7.50

Question 17

If the concentrations of the hydronium ion and hydroxide ion are equal to 1.025 × $10 ^ { - 7 }$ M each, the ion-product constant of liquid water is _____.

A) 1.051 × $10 ^ { - 14 }$
B) 1.141 × $10 ^ { - 13 }$
C) 1.261 × $10 ^ { - 15 }$
D) 1.571 × $10 ^ { - 7 }$
E) 1.891 × $10 ^ { - 7 }$

Question 18

The pH of any neutral solution is equal to the solution's $\mathrm { p } K _ { w }$ at that temperature.

Question 19

State three differences between an acid and a base based on the definitions of Arrhenius, Brønsted-Lowry, and Lewis.

Question 20

The pH of a solution can be monitored using an acid-base indicator.

Question 21

The larger the acid ionization constant, the stronger the acid and the higher the H⁺ concentration at equilibrium.

Question 22

The Lewis definition of acids and bases focuses on accepting or donating pairs of _____ rather than protons.

Question 23

The pH of a solution with 2.5 × 10^-6 M [H⁺] ion concentration is equal to _____.

Question 24

The K_a of an acid is _____, if its pK_a is equal to 5.74 at $60 ^ { \circ } \mathrm { C }$ .

A) 2.45×10^-3
B) 6.67×10^-5
C) 5.98×10^-6
D) 1.82×10^-6
E) 3.68×10^-5

Question 25

Chemists use an analogous _____ to describe the hydroxide ion concentration of the solution.

Question 26

HCl donates a proton to a water molecule thereby forming Cl⁻. Thus, HCl and Cl⁻ constitute a conjugate acid-base pair.

Question 27

In the reaction $\mathrm { HCl } + \mathrm { H } _ { 2 } \mathrm { Of } \quad \mathrm { H } _ { 3 } \mathrm { O } ^ { + } + \mathrm { Cl } ^ { - }$ , the number of conjugate acid-base pairs is ____.

A) zero
B) one
C) two
D) three
E) four

Question 28

A proton reacts with a water molecule to form the _____ ion.

Question 29

The $\mathrm { p } K _ { a }$ of acetic acid at $30 ^ { \circ } \mathrm { C }$ is _____, if its acid ionization constant is $3.2 \times 10 ^ { - 6 }$ .

A) 5.5
B) 2.7
C) 3.6
D) 4.8
E) 6.4

Question 30

Water is _____, meaning that it can behave as either an acid or a base, depending on the nature of the other reactant.

Question 31

If the pK_b of a conjugate base is equal to 10.9 at $45.0 ^ { \circ } \mathrm { C }$ , the value of its K_b is _____.

A) 1.26 × 10^-11
B) 6.25 × 10^-10
C) 4.89 × 10^-11
D) 2.35 × 10^-10
E) 9.84 × 10^-11

Question 32

Which of the following is true of the effect of a metal ion on the acidity of water?

A) The decrease in electron density makes it difficult for the water molecule to lose a proton.
B) The positive charge on the metal ion attracts electron density from the oxygen atoms of the water molecules.
C) A divalent ion has the same effect on the electron density as a monovalent ion of the same radius.
D) The larger the metal ion, the shorter the internuclear distance to the oxygen atom of the water molecule.
E) The larger the metal ion, the greater the effect of the metal on the electron density distribution in the water molecule.

Question 33

If the base dissociation constant of a butyrate ion at 25^oC is $2.20 \times 10 ^ { - 9 }$ , what is its pK_b?

A) 12.5
B) 11.6
C) 10.0
D) 7.44
E) 8.66

Question 34

Which of the following aqueous solutions of compounds is most likely to be neutral?
a. KCN
b. KCl
c. CH₃CO₂H
d. HCOOH
e. ₃

Question 35

The conjugate base of a strong acid is a very strong base.

Question 36

In pure water, the concentrations of the hydronium ion and hydroxide ion are equal, and the solution is therefore _____.

Question 37

The $\mathrm { p } K _ { a }$ of hydrochloric acid is _____, if the $\mathrm { p } K _ { b }$ of its conjugate base is 8.56 at $25 ^ { \circ } \mathrm { C }$ .

A) 6.78
B) 5.44
C) 4.32
D) 3.56
E) 2.24

Question 38

An acid-base equilibrium always favors the side with the stronger acid and base.

Question 39

In aqueous solutions, acids and bases can be defined in terms of the transfer of a proton from an acid to a base.

Question 40

Which of the following in the reaction $\mathrm { HCl } + \mathrm { H } _ { 2 } \mathrm { Of } \quad \mathrm { H } _ { 3 } \mathrm { O } ^ { + } + \mathrm { Cl } ^ { - }$ constitute a conjugate acid-base pair?

A) $\mathrm { HCl } \text { and } \mathrm { H } _ { 2 } \mathrm { O }$
B) $\mathrm { H } _ { 2 } \mathrm { O } \text { and } \mathrm { Cl } ^ { - }$
C) $\mathrm { HCl } \text { and } \mathrm { H } _ { 3 } \mathrm { O } ^ { + }$
D) $\mathrm { H } _ { 3 } \mathrm { O } ^ { + } \text {and } \mathrm { Cl } ^ { - }$
E) $\mathrm { H } _ { 2 } \mathrm { O } \text { and } \mathrm { H } _ { 3 } \mathrm { O } ^ { + }$

Question 41

The phenomenon in which a 0.1M aqueous solution of any strong acid contains 0.1M H₃O⁺, regardless of the identity of the strong acid is called the _____.

Question 42

Electron delocalization in the conjugate base decreases acid strength.

Question 43

The most important parameter for predicting the effect of a metal ion on the acidity of coordinated water molecules is the _____ of the metal ion.

Question 44

Which of the following acids will most likely be the strongest?

A) Acid A: pK_a = 5.68
B) Acid B: pK_a = 6.89
C) Acid C: pK_a = 2.45
D) Acid D: pK_a = 3.25
E) Acid E: pK_a = 4.50

Question 45

The base ionization constant (K_b) is also called the _____.

Question 46

Acid strengths of binary hydrides increase as we go down a column of the periodic table.

Question 47

A(n) _____ takes place when atoms or groups of atoms in a molecule other than those to which H is bonded induces a change in the distribution of electrons within the molecule.

Question 48

Which of the following bases will most likely be the strongest?

A) Base A: pK_b = 12.89
B) Base B: pK_b = 10.23
C) Base C: pK_b = 9.50
D) Base D: pK_b = 7.68
E) Base E: pK_b = 8.42

Question 49

Any inductive effect that withdraws electron density from an O-H bond increases the acidity of the compound.

Question 50

_____ such as H₂SO₄, H₃PO₄, and H₂CO₃ contain more than one ionizable proton, and the protons are donated in a stepwise manner.

Question 51

Explain the concept of conjugate acid-base pairs with an example.

Question 52

Reactions in which a salt reacts with water to give an acidic or basic solution are called _____ reactions.

Question 53

Which of the following binary hydrides has the lowest acid strength?

A) H₂Pb
B) H₂O
C) H₂S
D) H₂Se
E) H₂Te

Question 54

The larger the atom to which hydrogen is bonded, the stronger the bond.

Question 55

How does bond strength affect the acidity of a substance?

Question 56

Explain the variation in acid strength due to inductive effect.

Question 57

A(n) _____ can be defined as the reaction of an acid and a base to produce a salt and water.

Question 58

Explain the leveling effect phenomenon.

Question 59

_____ is the only common oxoacid in which a hydrogen atom is bonded to the central atom rather than oxygen.

A) Sulfuric acid
B) Nitric acid
C) Phosphorous acid
D) Carbonic acid
E) Nitrous acid

Question 60

Acid strengths of binary hydrides decrease as we go from left to right across a row of the periodic table.

Question 61

When a strong base is added to a solution of a polyprotic acid, the least acidic group is titrated first.

Question 62

The analytical concentration of an acid or a base is the final concentration.

Question 63

We use the stoichiometry of the neutralization reaction to calculate the amounts of acid and conjugate base present in solution after the neutralization reaction has occurred.

Question 64

The concentrations of the species in the reaction can be obtained by measuring the electrical conductivity of the solution.

Question 65

What volume of 0.500 M HCl is required if 25.0 mL of 0.400 M NaOH is added to it in order to achieve complete titration?

A) 20.0 mL
B) 10.0 mL
C) 30.0 mL
D) 5.00 mL
E) 15.0 mL

Question 66

The percent ionization in a solution of a weak base increases as the K_a or the K_b decreases.

Question 67

Given: pK_w = 14.00 If the values of pK_a and pK_b are 3.85 and 4.85 respectively, the value of pK is _____.

A) 5.30
B) -5.30
C) -1.00
D) 1.00
E) 8.70

Question 68

The percent ionization in a solution of a weak acid increases as the analytical concentration decreases.

Question 69

In the solution if the analytical concentration of the base is equal to 0.256M and its percent ionization is 2.5%, the value of the [OH]^- concentration is _____.

A) 4.8 × 10^-4M
B) 1.2 × 10^-3M
C) 2.4 × 10^-4M
D) 8.8 × 10^-3M
E) 6.4 × 10^-3M

Question 70

If the $\left[ \mathrm { OH } ^ { - } \right]$ concentration is equal to 0.023M and the analytical concentration of the same base is equal to 0.494 M, its percentage ionization is _____.

A) 4.7%
B) 2.6%
C) 3.5%
D) 6.8%
E) 8.2%

Question 71

If the analytical concentration of the acid is equal to 0.450 M and its percent ionization is 4.20%, the [H⁺] concentration in the acid is _____.

A) 3.24×10^-6M
B) 5.85×10^-3M
C) 1.89×10^-2M
D) 8.56×10^-3M
E) 6.25×10^-4M

Question 72

The pH at the midpoint of the titration of a weak acid is equal to the pK_a of the weak acid.

Question 73

Given: K_w = 1×10^-14 If the values of K_a and K_b are 3.5×10^-4 and 2.6×10^-4 respectively, the value of the equilibrium constant is _____.

A) 8.4×10⁴
B) 3.6×10⁶
C) 5.5×10⁷
D) 9.1×10⁶
E) 2.2×10⁴

Question 74

NaOH is an example of a monobasic strong base.

Question 75

The _____ is defined as the total concentration of all forms of an acid or a base that are present in solution, regardless of their state of protonation.

Question 76

The shape of the titration curve involving a strong acid and a strong base depends only on their identities, not their concentrations.

Question 77

For the equation $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } ( \mathrm { aq } ) f \mathrm { H } ^ { + } ( \mathrm { aq } ) + \mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } ^ { - } ( \mathrm { aq } )$ , if the final concentrations of [H⁺], [CH₃CO₂^?], and [CH₃CO₂H] are 0.0014 M, 0.0036 M, and 1.00M respectively the value of K_a is _____.

A) 3.5 ×10^-6
B) 5.0 ×10^-6
C) 1.3×10^-5
D) 4.5×10^-5
E) 8.0 × 10^-5

Question 78

If 50.0 mL of 0.600 M KOH is added to 80.0 mL of HNO₃ to reach the equivalence point, the molarity of HNO₃ is _____ M.

A) 0.720
B) 0.375
C) 0.545
D) 0.250
E) 0.825

Question 79

For the equation $\mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } ( \mathrm { aq } ) f \mathrm { H } ^ { + } ( \mathrm { aq } ) + \mathrm { CH } _ { 3 } \mathrm { CO } _ { 2 } ^ { - } ( \mathrm { aq } )$ , if the final concentrations of [H⁺], [CH₃CO₂^?], and [CH₃CO₂H] are 0.0014M, 0.0036M, and 1.00M respectively the value of pK_a is _____.

A) 2.7
B) 3.2
C) 6.8
D) 4.6
E) 5.3

Question 80

If the [H⁺] concentration of an acid is equal to 4.8 ×10^-3 M and the analytical concentration of the same acid is equal to 0.240 M, its percent ionization is _____.

A) 13%
B) 1.0%
C) 3.5%
D) 2.0%
E) 5.8%