Deck 15: Aqueous Equilibria-Chemistry of the Water World

Question 1

Which one of the following is NOT a strong acid?

A)nitric acid,HNO₃
B)sulfuric acid,H₂SO₄
C)carbonic acid,H₂CO₃
D)hydrochloric acid,HCl
E)perchloric acid,HClO₄

Answer 1

carbonic acid,H₂CO₃

Question 2

Which of the following is a strong base?

A)NH₃
B)KOH
C)C₅H₅N
D)B(OH)₃
E)N₂H₄

Answer 2

KOH

Question 3

Which one of the following statements is NOT correct?

A)A strong acid solution has a higher concentration than a weak acid solution.
B)A strong acid is ionized to a greater extent than a weak acid.
C)Hydrochloric acid is an example of a strong acid.
D)Acetic acid is an example of a weak acid.
E)The pH of a 0.1 M solution of acetic acid is higher than the pH of a 0.1 M solution of hydrochloric acid.

Answer 3

A strong acid solution has a higher concentration than a weak acid solution.

Question 4

In the Brønsted-Lowry definition of acids and bases,an acid __________

A)is a proton donor.
B)is a proton acceptor.
C)forms stable hydrogen bonds.
D)breaks stable hydrogen bonds.
E)corrodes metals.

Question 5

In the following reaction in aqueous solution,the acid reactant is __________ and its conjugate base product is __________. CH₃COOH(aq)+ NH₃(aq) $\leftrightarrows$ CH₃COO^-(aq)+ NH₄⁺(aq)

A)CH₃COOH; CH₃COO^-
B)CH₃COOH; NH₄⁺
C)NH₃; CH₃COO^-
D)NH₃; NH₄⁺
E)CH₃COOH; H₃O⁺

Question 6

Which one of the following is a strong acid?

A)nitrous acid,HNO₂
B)sulfurous acid,H₂SO₃
C)carbonic acid,H₂CO₃
D)hydrofluoric acid,HF
E)perchloric acid,HClO₄

Question 7

In the following reaction in aqueous solution,the acid reactant is __________,and its conjugate base product is __________. CH₃NH₂(aq)+ HSO₄(aq)^- $\leftrightarrows$ CH₃NH₃⁺(aq)+ SO₄^2-(aq)

A)CH₃NH₂; CH₃NH₃⁺
B)CH₃NH₂; SO₄^2-
C)HSO₄^-; CH₃NH₃⁺
D)HSO₄^-; SO₄^2-
E)HSO₄^-; H₃O⁺

Question 8

In the Brønsted-Lowry definition of acids and bases,a base __________

A)is a proton donor.
B)is a proton acceptor.
C)forms stable hydrogen bonds.
D)breaks stable hydrogen bonds.
E)corrodes metals.

Question 9

Which of the following statements regarding acid and base ionization in water is NOT correct?

A)A hydrogen atom directly bonded to an oxygen atom in a molecule is always significantly more acidic than water.
B)In strong acids,the acidic protons are generally bonded to highly electronegative elements such as O,Cl,Br,or I.
C)When a hydrogen atom is released as an H⁺ ion from an electronegative atom in an acid,the bonding pair of electrons remains on the electronegative atom.
D)Ionization of a strong acid in water is assisted by the strong dipole-dipole interactions between its ionizable H atoms and the O atoms in water molecules.
E)Ionization of water to form hydroxide in the presence of a base is often assisted by strong dipole-dipole interactions between H atoms in water and a lone pair of electrons in the base.

Question 10

Which of the following is a strong acid?

A)HNO₃
B)H₂S
C)HNO₂
D)HCO₃^-
E)HOCl

Question 11

Which of the following is a strong acid?

A)HClO
B)HClO₂
C)HClO₃
D)HClO₄
E)none of these is a strong acid

Question 12

Which of these is a strong acid that ionizes to make a weak acid?

A)H₂SO₃
B)H₂SO₄
C)H₃PO₄
D)HNO₃
E)HCl

Question 13

Which sketch best represents the qualitative molecular view of an aqueous solution of nitrous acid? (Water molecules are not shown explicitly.)

A)
B)
C)
D)
E)none of these

Question 14

In the following reaction in aqueous solution,the acid reactant is __________ and the base reactant is __________. N₂H₄(aq)+ H₂O( ) $\leftrightarrows$ OH^-(aq)+ N₂H₅⁺(aq)

A)N₂H₄; OH^-
B)N₂H₄; H₂O
C)H₂O; N₂H₄
D)H₂O; OH^-
E)N₂H₄; N₂H₅⁺

Question 15

Which statement about nitrous acid and nitric acid is correct?

A)They are both weak acids.
B)They are both strong acids.
C)They both have one ionizable proton.
D)Nitrous acid has the formula HNO₃.
E)Nitric acid has the formula HNO₂.

Question 16

In the following reaction in aqueous solution,the acid reactant is __________ and the base reactant is __________. OH^-(aq)+ C₆H₅NH₃⁺(aq) $\leftrightarrows$ C₆H₅NH₂(aq)+ H₂O( )

A)H₂O; OH^-
B)C₆H₅NH₃⁺; C₆H₅NH₂
C)H₂O; C₆H₅NH₂
D)C₆H₅NH₃⁺; OH^-
E)H₂O; C₆H₅NH₃⁺

Question 17

Which sketch best represents the qualitative molecular view of an aqueous solution of nitric acid? (Water molecules are not shown explicitly.)

A)
B)
C)
D)
E)none of these

Question 18

Which one of the following is NOT a strong base?

A)lithium hydroxide,LiOH
B)sodium hydroxide,NaOH
C)potassium hydroxide,KOH
D)calcium hydroxide,Ca(OH)₂
E)ammonium hydroxide,NH₄OH

Question 19

Which of the following is a strong acid?

A)H₂SO₃
B)H₃PO₄
C)HBrO
D)HF
E)HNO₃

Question 20

In the following reaction in aqueous solution,the acid reactant is __________ and the base reactant is __________. HCOOH(aq)+ H₂O( ) $\leftrightarrows$ HCOO^-(aq)+ H₃O⁺(aq)

A)HCOOH; HCOO^-
B)H₂O; HCOOH
C)H₂O; HCOO^-
D)H₂O; H₃O⁺
E)HCOOH; H₂O

Question 21

Suppose an aqueous solution initially contains one mole of hydrochloric acid and one mole of ammonia.Which of the following statements best describes the solution once it comes to equilibrium?

A)The solution is neutral because the ammonia neutralizes the hydrochloric acid.
B)The solution is highly acidic due to the ionization of HCl,HCl(aq) $\to$ H⁺(aq)+ Cl^-(aq).
C)The solution is slightly acidic due to the equilibrium,NH₄⁺(aq) $\leftrightarrows$ NH₃(aq)+ H⁺(aq).
D)The solution is slightly basic due to the equilibrium,NH₃(aq)+ H₂O( ) $\leftrightarrows$ NH₄⁺(aq)+ OH^-(aq).
E)The solution is slightly basic due to the equilibrium,Cl^-(aq)+ H₂O( ) $\leftrightarrows$ HCl(aq)+ OH^-(aq).

Question 22

Three acids found in foods are lactic acid (in milk products),oxalic acid (in rhubarb),and malic acid (in apples).The pK_a values are LA = 3.88,OA = 1.23,and MA = 3.40.Which list has these acids in order of decreasing acid strength?

A)LA > OA > MA
B)LA > MA > OA
C)OA > MA > LA
D)OA > LA > MA
E)MA > LA > OA

Question 23

The degree of ionization of a weak acid __________ I.varies with the concentration of the acid.
II.depends on the value of K_a.
III.is 100%.
IV.is greater than 50% but less than 100%.

A)I only
B)II only
C)III only
D)both I and II
E)IV only

Question 24

Use the following acid ionization constants to identify the correct decreasing order of base strengths.
HF $\quad$ $\quad$ K_a = 6.8 $\times$ 10^-4
HNO₂ $\quad$ K_a = 4.5 $\times$ 10^-4
HCN $\quad$ K_a = 6.2 $\times$ 10^-10

A)CN^- > NO₂^- > F^-
B)NO₂^- > F^- > CN^-
C)F^- > CN^- > NO₂^-
D)F^- > NO₂^- > CN^-
E)NO₂^- > CN^- > F^-

Question 25

Given the following K_a values,which of the following acids has the strongest conjugate base in water?

A)benzoic
B)chlorous
C)iodic
D)acrylic
E)cyanic

Question 26

Which of the following compounds cannot be a Brønsted-Lowry base?

A)OH^-
B)H₂O
C)NH₃
D)NH₄⁺
E)SH^-

Question 27

Which one of the following is a conjugate acid-base pair?

A)NH₃ and NH₄⁺
B)H₃O⁺ and OH^-
C)NH₂^- and NH₄⁺
D)H₂O and O^2-
E)NaF and F^-

Question 28

Which of the following lists the conjugate acid of HAsO₄^2- first and its conjugate base second?

A)H₃O⁺; AsO₄^3-
B)AsO₄^3-; H₂AsO₄^-
C)H₃AsO₄; AsO₄^3-
D)AsO₄^3-;H₃AsO₄
E)H₂AsO₄^-; AsO₄^3-

Question 29

Solutions of sodium salts of the acids in the following table are prepared with an initial concentration of 0.500 M.Which solution will have the highest pH and be the most basic?

A)NaA
B)NaB
C)NaC
D)NaD
E)All will have the same pH because the concentrations are the same.

Question 30

Which one of the following is NOT a conjugate acid-base pair?

A)NH₃ and NH₄⁺
B)H₃O⁺ and OH^-
C)H₂PO₄^- and HPO₄^2-
D)HS^- and H₂S
E)NH₃ and NH₂^-

Question 31

Which one of the following is NOT a conjugate acid-base pair?

A)NH₃ and NH₂^-
B)HNO₃ and HNO₂
C)HI and I^-
D)H₂PO₄^- and HPO₄^2-
E)H₂O and OH^-

Question 32

Which of the following statements regarding the leveling effect is NOT correct?

A)All strong acids completely ionize in water and appear to have the same strength.
B)All strong bases completely hydrolyze in water and appear to have the same strength.
C)The strongest base that can exist in water is OH^-.
D)The strongest acid that can exist in water is H₃O⁺.
E)All strong acids and bases are equally strong,even in solvents other than water.

Question 33

Three acids found in foods are lactic acid (in milk products),oxalic acid (in rhubarb),and malic acid (in apples).The pK_a values are LA = 3.88,OA = 1.23,and MA = 3.40.Which list has the conjugate bases of these acids in order of decreasing strength?

A)lactate > oxalate > malate
B)oxalate > malate > lactate
C)lactate > malate > oxalate
D)oxalate > lactate > malate
E)malate > lactate > oxalate

Question 34

Which of the following is the conjugate acid of the hydrogen phosphate ion,HPO₄^2-?

A)H₃PO₄
B)H₂PO₄^-
C)HPO₄^2-
D)PO₄^3-
E)H₃O⁺

Question 35

Ammonia (NH₃)acts as a weak base in aqueous solution.What is the acid that reacts with this base when ammonia is dissolved in water?

A)None; there are no acids in pure water.
B)H₂O
C)NH₄⁺
D)Trick question; because no acids are present,ammonia cannot act as a base.
E)oxygen that always is dissolved in water

Question 36

Which one of the following is a conjugate acid-base pair?

A)NaF and F^-
B)HNO₃ and HNO₂
C)HI and I^-
D)NH₄⁺ and NH₂^-
E)H₂O and H₂O₂

Question 37

Given the following K_a values,which of the following acids is the strongest in water?

A)benzoic
B)chlorous
C)iodic
D)acrylic
E)cyanic

Question 38

Which one of the following is NOT correct?

A)HClO₄ is a stronger acid than HClO₃.
B)HClO is a stronger acid than HCl.
C)HClO₂ is a weaker acid than HClO₃.
D)ClO^- is a stronger base than ClO₂^-.
E)ClO₂^- is a stronger base than Cl^-.

Question 39

Solutions of each of the hypothetical acids in the following table are prepared with an initial concentration of 0.100 M.Which of the four solutions will have the lowest pH and be most acidic?

A)HA
B)HB
C)HC
D)HD
E)All will have the same pH because the concentrations are the same.

Question 40

The degree of ionization of a strong acid is __________

A)100%.
B)between 1 and 10%.
C)between 10 and 100%.
D)dependent on the concentration of the acid.
E)dependent the value of K_a.

Question 41

When pure water autoionizes,which species are produced?

A)O^2-,OH^-,H₃O⁺,and H₂O⁺
B)OH^- and H₃O⁺
C)O^2- and H₄O²⁺
D)H⁺ and OH^-
E)2 H⁺ and O^2-

Question 42

Which ending to the statement is NOT correct? The weak acid HY will be stronger than the weak acid HZ if __________

A)more Lewis resonance structures can be written for the Y ion than for the Z ion.
B)Y is more electronegative than Z.
C)the Y ion has more oxygen atoms than the Z ion.
D)the H-Y bond is weaker than the H-Z bond.
E)the H-Y bond is less polar then the H-Z bond.

Question 43

Suppose 0.50 L of a HNO₃ solution has a pH of 3.30.How many moles of HNO₃ must have been initially dissolved in the solution?

A)2.5 $\times$ 10^-4 moles
B)5.0 $\times$ 10^-4 moles
C)1.7 $\times$ 10^-3 moles
D)1.0 $\times$ 10^-3 moles
E)1.8 $\times$ 10^-2 moles

Question 44

Which statement,A-D,is NOT correct? If all are correct,respond E.Pure water at 25°C has __________

A)K_w = 1.0 $\times$ 10^-14.
B)pOH = 7.
C)[H₃O⁺] = [OH^-].
D)pH = 7.
E)A-D are all correct.

Question 45

When [H⁺] = 4.0 $\times$ 10^-9 M in water at 25°C,then __________

A)pH = 9.40.
B)pH = 7.00.
C)pH = -8.40.
D)pH = 8.40.
E)pH = -9.40.

Question 46

A solution with pH of 9.50 has a pOH of __________

A)9.50.
B)0.50.
C)4.50.
D)23.5.
E)19.0.

Question 47

In each of the following,the stronger acid is identified and an explanation is given.All except one are correct statements.Which one is NOT correct?

A)HCl > HF because the HF bond energy is larger than the HCl bond energy.
B)HCO₃^- > H₂CO₃ because the negative charge stabilizes the loss of a proton.
C)CCl₃COOH > CH₃COOH because electronegative substituents stabilize the conjugate base.
D)HBrO₃ > HBrO₂ because of the additional electronegative oxygen atom.
E)ClOH > BrOH because Cl is more electronegative than Br.

Question 48

Which one of the following statements is NOT correct?

A)HIO is a stronger acid than HClO.
B)HClO is a stronger acid than HBrO.
C)HClO₃ is a stronger acid than HClO₂.
D)HPO₄^2- is a weaker acid than H₂PO₄^-.
E)H₂SO₄ is a stronger acid than H₂SO₃.

Question 49

Which expression defines the autoionization constant for water,K_w?

A)[H₃O⁺][OH^-]
B)[H₂O][H₃O⁺]
C)[OH^-][H₂O]
D)[H₄O²⁺][O^2-]
E)[H₂O][H₂O]

Question 50

Suppose 0.035 moles of HCl is dissolved in enough water to produce 750 mL of solution.What is the pH?

A)pH = 4.33
B)pH = 7.00
C)pH = 1.58
D)pH = -4.33
E)pH = 1.33

Question 51

The pH of a popular soft drink is 3.40; what is its hydronium ion concentration?

A)5.0 $\times$ 10^-4 M
B)4.0 $\times$ 10^-4 M
C)2.5 $\times$ 10³ M
D)1.0 $\times$ 10^-7 M
E)5.0 $\times$ 10^-5 M

Question 52

Which one of the following is NOT related to the water autoionization constant,K_w? If all are related,respond E.

A)[H₃O⁺] [OH^-]
B)1.0 *10^-14 at 25°C
C)2H₂O $\leftrightarrows$ H₃O⁺ + OH^-
D)pH = 7 at 25°C
E)A-D are all related to K_w.

Question 53

Sometimes liquid ammonia,NH₃,is used as a solvent rather than water.Which expression defines the ammonia autoionization counterpart of K_w?

A)[H₃O⁺][OH^-]
B)[NH₃][NH₄⁺]
C)[NH₂^-][NH₄⁺]
D)[H₃O⁺][NH₂^-]
E)[NH₄⁺][OH^-]

Question 54

Which of the following statements regarding acidity,basicity,pH,and pOH is NOT correct?

A)[H⁺] = [OH^-] in a neutral solution,and the pH = 7 at 25°C.
B)[H⁺] > [OH^-] in an acidic solution,and the pH < 7 at 25°C.
C)[H⁺] < [OH^-] in an basic solution,and the pH > 7 at 25°C.
D)If [H⁺] increases in a solution,[OH^-] must decrease.
E)If the pH of a solution increases,its [H⁺] increases.

Question 55

Which of the following shows a relationship expressed in the correct number of significant figures?

A)[H⁺] = 0.1270 M; pH = 0.8962
B)pH = 2.273; [H⁺] = 5.333 $\times$ 10^-3 M
C)[H⁺] = 1.80 $\times$ 10^-2 M; pH = 1.74
D)pH = 8.9; [H⁺] = 1.3 $\times$ 10^-9 M
E)pH = 4.0; [H⁺] = 1 $\times$ 10^-4 M

Question 56

Pure water at any temperature has __________

A)a pH less than 7.
B)a pOH more than 7.
C)[H₃O⁺] = [OH^-].
D)pH = 7.
E)no hydronium ions in it.

Question 57

Carbon dioxide in the atmosphere in rainwater often lowers the pH to 5.0-5.6.The rainwater is __________

A)neutral.
B)acidic.
C)basic.
D)gray.
E)poisonous.

Question 58

In evaluating the pH of an aqueous weak acid solution,__________ usually can be ignored.

A)the concentration of the weak acid
B)the concentration of hydronium ion produced by the autoionization of water
C)the reaction of the weak acid with water
D)the concentration of the ionized hydronium ion
E)the concentration of the conjugate base

Question 59

When [H⁺] = 1.0 $\times$ 10^-7 M in water at 25°C,then __________

A)pH = 1.
B)pH = 10^-7.
C)[OH^-] = 1.0 $\times$ 10^-7 M.
D)[OH^-] = 1.0 $\times$ 10⁷ M.
E)[OH^-] = 0 M.

Question 60

Which one of the following,A-D,is correct? If all are correct,respond E.

A)K₂SO₃ is a stronger base than KHSO₃.
B)K₂CO₃ is a weaker base than KHCO₃.
C)NaHSO₃ is a stronger acid than NaHSO₄.
D)Na₂HPO₄ is a weaker base than NaH₂PO₄.
E)All of these statements are correct.

Question 61

Codeine (C₁₈H₂₁NO₃,299.4 g/mol)is a weak base.Suppose a 2.00 g pain tablet containing 30.0 mg codeine is dissolved in water to produce a 0.100 L solution with a pH of 9.470.Based on this information,determine the value of K_b for codeine.

A)8.6 $\times$ 10^-6
B)3.4 $\times$ 10^-9
C)9.3 $\times$ 10^-7
D)2.9 $\times$ 10^-2
E)8.7 $\times$ 10^-7

Question 62

The first disinfectant used by Joseph Lister was called carbolic acid.This substance now is known as phenol,C₆H₅OH (pK_a = 9.9).What is the pH of a 0.10 M solution of phenol?

A)3.5
B)10.0
C)6.5
D)5.5
E)4.5

Question 63

The pH of a 0.250 M cyanuric acid solution is 3.690.What is the value of K_a?

A)8.17 $\times$ 10^-4
B)1.04 $\times$ 10^-8
C)1.67 $\times$ 10^-7
D)2.04 $\times$ 10^-4
E)5.10 $\times$ 10^-5

Question 64

In an experiment,0.438 L of 0.152 M NaOH is diluted with water to a final volume of 3.00 L.What is the pH of the dilute solution?

A)1.654
B)13.182
C)1.295
D)12.705
E)12.346

Question 65

A cup of coffee has a hydroxide ion concentration of 1 $\times$ 10^-10 M.What is the pH of this coffee?

A)1.0 $\times$ 10^-4
B)4.0
C)10.0
D)7.0
E)-10.0

Question 66

The acid ionization equilibrium constant,K_a,describes which of the following reactions (where HA is a generic weak acid)?

A)HA + OH^- $\leftrightarrows$ H₂O + A^-
B)HA + H₂O $\leftrightarrows$ H₃O⁺ + A^-
C)HA + H₃O⁺ $\leftrightarrows$ H₂A⁺ + H₂O
D)HA + H₂A⁺ $\leftrightarrows$ H₂A⁺ + HA
E)H₃O⁺ + A^- $\leftrightarrows$ HA + H₂O

Question 67

The concentration of acetic acid (pK_a = 4.75)in vinegar is about 1.0 M.With this information,what do you predict the pH of vinegar to be?

A)4.75
B)2.4
C)4.0 $\times$ 10^-3
D)7.0
E)5.35

Question 68

Identify the expression that results after multiplying K_a of HA and K_b of A^-.

A)
B)
C)
D)
E)

Question 69

A solution with a pOH of 4.30 has a [H⁺] of __________

A)6.8 $\times$ 10^-9 M.
B)3.2 $\times$ 10^-4 M.
C)4.8 $\times$ 10^-5 M.
D)2.0 $\times$ 10^-10 M.
E)4.3 M.

Question 70

What is the pH of a 0.500 M solution of trimethylamine (pK_b = 4.13)?

A)2.22
B)11.8
C)0.00609
D)4.42
E)5.91

Question 71

What is the pH of a 0.010 M acetic acid solution? (K_a for acetic acid is 1.76 $\times$ 10^-5.)

A)2.00
B)4.74
C)2.74
D)3.38
E)6.74

Question 72

A 0.100 M monoprotic weak acid solution has a pH of 3.00.What is the pK_a of this acid?

A)5.00
B)0.10
C)3.00
D)9.99
E)6.00

Question 73

The base ionization constant K_b describes which of the following reactions for a weak base,B,in aqueous solution?

A)B + H⁺ $\leftrightarrows$ BH⁺
B)B + H₃O⁺ $\leftrightarrows$ BH⁺ + H₂O
C)B + H₂O $\leftrightarrows$ BH⁺ + OH^-
D)B + OH^- $\leftrightarrows$ BH^- + O^2-
E)BH⁺ + OH^- $\leftrightarrows$ B + H₂O

Question 74

Which of the following is the K_b expression for the conjugate base of hydrocyanic acid,HCN?

A)
B)
C)
D)
E)

Question 75

A solution with a pOH of 6.92 has an [OH^-] of __________

A)1.2 $\times$ 10^-7 M.
B)9.2 $\times$ 10^-6 M.
C)6.8 $\times$ 10^-6 M.
D)7.1 M.
E)6.9 M.

Question 76

Which of the following is the K_a expression for the conjugate acid of trimethylamine,(CH₃)₃N?

A)
B)
C)
D)
E)

Question 77

Piperidine,C₅H₁₁N,is a weak base in water.If a 0.120 M piperidine solution has a pH of 12.077,what is the K_b of piperidine?

A)4.78 $\times$ 10^-2
B)2.98 $\times$ 10^-3
C)1.19 $\times$ 10^-3
D)1.31 $\times$ 10^-3
E)6.98 $\times$ 10^-12

Question 78

What is the hydronium ion concentration of a 0.010 M acetic acid solution? (K_a for acetic acid is 1.76 $\times$ 10^-5.)

A)1.8 $\times$ 10^-3
B)1.8 $\times$ 10^-5
C)1.0 $\times$ 10^-2
D)1.8 $\times$ 10^-7
E)4.2 $\times$ 10^-4

Question 79

Boric acid frequently is used as an eyewash to treat eye infections.The pH of a 0.050 M boric acid solution is 5.28.What is the value of K_a?

A)5.3 $\times$ 10^-6
B)5.5 $\times$ 10^-10
C)5.4 $\times$ 10^-8
D)5.8 $\times$ 10^-4
E)5.3 $\times$ 10^-12

Question 80

The acidic ingredient in vinegar is acetic acid.If the pH of a particular brand of vinegar is 2.40 and the molar concentration of acetic acid in the vinegar is 0.85 M,determine the value of K_a for acetic acid.

A)2.5 $\times$ 10^-5
B)5.0 $\times$ 10^-5
C)4.7 $\times$ 10^-3
D)1.9 $\times$ 10^-5
E)7.4 $\times$ 10^-3