Chapter 14 Acids and BBases

Solid calcium hydroxide is dissolved in water until the pH of the solution is 11.44. The hydroxide ion concentration [OH-] of the solution is: 3.6 × 10-12 M 5.5×10-3M 2.8×10-3M 1.4×10-3M none of these

2.8×10-3M

The equilibrium constant for the reaction NH4+ + OH- NH3 + H2O is: A) B) C) D)

A)

Calculate the pH of 0.203 M HNO3(aq). A) 0.693B) 2.030C) -1.140 D) 13.797

A) 0.693

For nitrous acid, HNO2, Ka = 4.0 × 10-4. Calculate the pH of 0.27 M HNO2. A) 1.98B) 0.57C) 3.97 D) 12.02

A) 1.98

Calculate the pH of a 0.13 M solution of HOCl, Ka = 3.5 × 10-8. A) 4.17B) 8.34C) 9.83 D) 3.76

A) 4.17

The pH of a 1.0 M aqueous solution of NaCl is: A) 7.0 B) greater than 7.0 C) less than 7.0 D) not enough information given

A) 7.0

Identify the strongest base. A) CH3O-B) CH3OHC) CN- D) H2O

A) CH3O-

Using the following Ka values, indicate the correct order of base strength. HNO2 Ka = 4.0 × 10-4HF Ka =7.2×10-4HCN Ka = 6.2 × 10-10 A) CN- >NO2- >F- >H2O>Cl- B) Cl- >H2O>F->NO2- >CN- C) CN- >F- >NO2- >Cl- >H2O D) H2O>CN- >NO2- >F- >Cl-

A) CN- >NO2- >F- >H2O>Cl-

Which of the following species is present in the greatest concentration in a 0.100 M H2SO4 solution in H2O? A) H3O+ B) HSO4- C) H2SO4 D) All species are in equilibrium and therefore have the same concentration. E) SO42-

A) H3O+

Which is the strongest acid of the following? A) HClO2B) HClOC) HBrO D) HIO

A) HClO2

For the equilibrium that exists in an aqueous solution of nitrous acid (HNO2, a weak acid), the equilibrium constant expression is:

A) K=[H+][NO2-]/[HNO2]

Which of the following indicates the most basic solution? A) [H+]=1×10-10M B) pOH = 6.7 C) [OH-]=7×10-5M D) pH=4.2 E) At least two of the solutions are equally basic.

A) [H+]=1×10-10M

A solution in which the pOH is 12.1 would be described as A) very acidic B) slightly acidic C) neutral D) very basic E) slightly basic

A) very acidic

Calculate the pH of a 0.031 M strong acid solution. A) -1.51B) 1.51C) 12.49 D) 15.51

B) 1.51

Calculate the pH of a 0.51 M solution of KOH. A) 14.00B) 13.71C) 0.29 D) 0.51

B) 13.71

In a solution prepared by dissolving 0.100 mole of propanoic acid in enough water to make 1.00 L of solution, the pH is observed to be 2.832. The Ka for propanoic acid (HC3H5O2) is: A) 1.47 × 10-3 B) 2.20 × 10-5 C) 1.49 × 10-2 D) 4.55 × 10-10

B) 2.20 × 10-5

If an acid, HA, is 14.7% dissociated in a 1.0 M solution, what is the Ka for this acid? A) 1.7 × 10-1 B) 2.5 × 10-2 C) 1.5 × 10-1 D) 3.9 × 101

B) 2.5 × 10-2

A 8.5 × 10-3 M solution of a weak acid is 4.6% dissociated at 25°C. In a 8.5 × 10-4 M solution, the percentage of dissociation would be A) the same B) > 4.6% C) < 4.6% D) need to know the Ka of the acid to answer this

B) > 4.6%

HA and HB are both weak acids in water, and HA is a stronger acid than HB. Which of the following statements is correct? A) A- is a stronger base than B-, which is a stronger base than H2O, which is a stronger base than Cl-. B) B- is a stronger base than A-, which is a stronger base than H2O, which is a stronger base than Cl-. C) B- is a stronger base than A-, which is a stronger base than Cl-, which is a stronger base than H2O. D) Cl- is a stronger base than A-, which is a stronger base than B-, which is a stronger base than H2O.

B) B- is a stronger base than A-, which is a stronger base than H2O, which is a stronger base than Cl-.

In which of the following reactions does the H2PO4- ion act as an acid? A) H3PO4 + H2O → H3O+ + H2PO4- B) H2PO4- + H2O → H3O+ + HPO42- C) H2PO4- + OH- → H3PO4 + O2- D) The ion cannot act as an acid.

B) H2PO4- + H2O → H3O+ + HPO42-

The dihydrogenphosphate ion, H2PO4-, has both a conjugate acid and a conjugate base. These are, respectively: A) H3PO4, PO43- B) H3PO4, HPO42- C) H2PO4-, HPO42- D) HPO42-, PO43-

B) H3PO4, HPO42-

The following three equations represent equilibria that lie far to the right. HNO3(aq) + CN-(aq) HCN(aq) + NO3-(aq) ____ 17. HCN(aq) + OH-(aq)H2O(l) + CH3O-(aq) CH3OH(aq) + OH-(aq) Identify the strongest acid. A) HCNB) HNO3C) H2O D) OH-

B) HNO3

Consider the reaction HOCl + F- HF + OCl- Given that Ka for HOCl is 3.5 × 10-8 and the Ka for HF is 7.2 × 10-4 (both at 25°C), which of the following is true concerning K for the above reaction at 25°C? A) K is greater than 1. B) K is less than 1. C) Kisequalto1. D) Cannot be determined with the above information.

B) K is less than 1.

If you know Kb for ammonia, NH3, you can calculate the equilibrium constant, Ka, for the following reaction: NH4+ NH3 + H+ by the equation:A) Ka=Kw×KbB) Ka=Kw/Kb C) Ka=1/Kb D) Ka=Kb/Kw

B) Ka=Kw/Kb

Which of the following is not true for a solution at 25°C that has a hydroxide concentration of 2.5 × 10-6 M? A) Kw =1×10-14 B) The solution is acidic. C) The solution is basic. D) The [H+] is 4.0 × 10-9 M. E) The Kw is independent of what the solution contains.

B) The solution is acidic.

Consider the following reactions: a) Al3+ + 6H2O Al(OH2)63+ b) Al(OH2)63+ Al(OH)(OH2)52+ + H+ c) OCl- + H2O HOCl + OH- d) CN- + H+ HCNWhich is associated with the definition of Ka? A) aB) bC) c D) d

B) b

sodium oxide (Na2O) A) acidic B) basic C) neutral D) cannot tell

B) basic

solid sodium carbonate (Na2CO3) A) acidic B) basic C) neutral D) cannot tell

B) basic

The pH of a 1.0 M sodium acetate solution is: A) 7.0 B) greater than 7.0 C) less than 7.0 D) not enough information given

B) greater than 7.0

Acetic acid, (HC2H3O2) is a weak acid (Ka = 1.8 × 10-5). Calculate the pH of a 15.1 M HC2H3O2 solution. A) -1.18 B) 3.57 C) 1.78 D) 1.18

C) 1.78

Calculate the [H+] in a solution that has a pH of 2.73. A) 2.7M B) 11.3 M C) 1.9×10-3M D) 5.4 × 10-12 M E) none of these

C) 1.9×10-3M

Calculate the pOH of a 4.9 M solution of HCl. A) -0.69B) 13.31C) 14.69 D) 0.69

C) 14.69

The pH of a 0.118 M solution of an aqueous weak acid (HA) is 3.20. The Ka for the weak acid is: A) 5.4 × 10-3 B) 4.0 × 10-7 C) 3.4 × 10-6 D) 3.2

C) 3.4 × 10-6

The pKa of HOCl is 7.5. Calculate the pH of a 0.31 M solution of HOCl. A) 7.50B) 6.50C) 4.00 D) 10.00

C) 4.00

Saccharin is a monoprotic acid. If the pH of a 4.41 × 10-3 M solution of this acid is 2.53, what is the Ka of saccharin? A) 8.7 × 10-6 B) 2.0 × 10-3 C) 6.0 × 10-3 D) 2.9 × 10-3

C) 6.0 × 10-3

What is the pOH of pure water at 65oC? (Kw at 65oC = 1.20 × 10-13) A) 7.540B) 7.000C) 6.460 D) 12.921

C) 6.460

The pH of a solution at 25°C in which [OH-] = 3.9 × 10-5 M is: A) 4.41 B) 3.90 C) 9.59 D) 4.80 E) none of these

C) 9.59

The equilibrium constants (Ka) for HCN and HF in H2O at 25°C are 6.2 × 10-10 and 7.2 × 10-4, respectively. The relative order of base strengths is: A) F- >H2O>CN- B) H2O>F- >CN- C) CN- >F- >H2O D) F- >CN- >H2O

C) CN- >F- >H2O

Which of the following reactions is associated with the definition of Kb? A) Zn(OH2)62+ [Zn(OH2)5OH]+ + H+ B) CN-+H+ HCN C) F-+H2OD) Cr3+ + 6H2O HF+OH- Cr(OH2)63+

C) F-+H2OD) Cr3+ + 6H2O

Which of the following is a conjugate acid/base pair? A) HCl/OCl-B) H2SO4/SO42-C) NH4+/NH3 D) H3O+/OH-

C) NH4+/NH3

The autoionization of water, as represented by the below equation, is known to be endothermic. Which of the following correctly states what occurs as the temperature of water is raised? H2O(l) + H2O(l) H3O+(aq) + OH-(aq) A) The pH of the water does not change, and the water remains neutral. B) The pH of the water decreases, and the water becomes more acidic. C) The pH of the water decreases, and the water remains neutral. D) The pH of the water increases, and the water becomes more acidic.

C) The pH of the water decreases, and the water remains neutral.

Which is associated with the definition of Kb? A) aB) bC) c D) d

C) c

Select the answer that best describes an aqueous solution made from each of the following substances: solid sodium nitrate (NaNO3) A) acidic B) basic C) neutral D) cannot tell

C) neutral

Which of the following would give the highest pH when dissolved in water to form a 0.10 M solution? A) a strong acid B) a weak acid C) the potassium salt of a weak acid D) the potassium salt of a strong acid

C) the potassium salt of a weak acid

Consider the reaction HNO2(aq) + H2O(l) H3O+(aq) + NO2-(aq). Which species is a conjugate base? A) HNO2(aq) B) H2O(l) C) two of these D) NO2-(aq)

C) two of these

The equilibrium constant for the reaction A- + H+=HA A) Ka B) Kb C)1/Ka D)Kw/Kb

C)1/Ka

Calculate the [H+] in a solution that has a pH of 9.88. A) 4.1M B) 9.9M C) 7.6×10-5M D) 1.3 × 10-10 M E) none of these

D) 1.3 × 10-10 M

HA is called: What is the equilibrium constant for the following reaction? N3- + H3O+ HN3 + H2O The Ka value for HN3 = 1.9 × 10-5. A) 5.3 × 10-10 B) 1.9 × 10-9 C) 1.9 × 10-5 D) 5.3 × 104

D) 5.3 × 104

The salt BX, when dissolved in water, produces an acidic solution. Which of the following could be true? A) HX is a weak acid. B) HX is a strong acid. C) The cation B+ is a weak acid. D) All of the above could be true.

D) All of the above could be true.

Which of the following statements are true? A) The pH of a strong acid is always lower than the pH of a weak acid. B) The pH of a solution can never be negative. C) For a conjugate acid-base pair, Ka = 1/Kb. D) All of the statements A-C are false.

D) All of the statements A-C are false.

For which of the following 0.10 M diprotic acids would the second dissociation affect the pH significantly? A) H2A;Ka1 =4.2×10-2,Ka2 =1.8×10-7 B) H2B; Ka1 =2.4×10-4,Ka2 =6.1×10-8 C) H2C; Ka1 =1.3×10-4,Ka2 =5.2×10-9 D) H2D;Ka1 =1.8×10-3,Ka2 =9.3×10-4 E) The second dissociation never affects the pH significantly.

D) H2D;Ka1 =1.8×10-3,Ka2 =9.3×10-4

For the stepwise dissociation of aqueous H3PO4, which of the following is not a conjugate acid-base pair? A) HPO42- and PO43- B) H3PO4 and H2PO4- C) H2PO4- and HPO42- D) H2PO4- and PO43-

D) H2PO4- and PO43-

The hydrogen sulfate or bisulfate ion HSO4- can act as either an acid or a base in water solution. In which of the following equations does HSO4- act as an acid? A) HSO4- + H2O → H2SO4 + OH- B) HSO4- + H3O+ → SO3 + 2H2O C) HSO4- + OH- → H2SO4 + O2- D) HSO4- + H2O → SO42- + H3O+

D) HSO4- + H2O → SO42- + H3O+

You have 100.0 mL of a solution of hydrochloric acid that has a pH of 3.00. You add 100.0 mL of water to this solution. What is the resulting pH of the solution? A) The pH = 5.00 (the average of 3.00 and 7.00). B) The pH = 10.00 (3.00 + 7.00 = 10.00). C) The pH = 3.00 (water is neutral and does not affect the pH). D) None of the above is correct, but the pH must be greater than 3.00.

D) None of the above is correct, but the pH must be greater than 3.00.

The sodium salt, NaA, of a weak acid is dissolved in water; no other substance is added. Which of these statements (to a close approximation) is true? A) [H+] = [A-] B) [H+] = [OH-] C) [A-] = [OH-] D) [HA] = [OH-]

D) [HA] = [OH-]

Which of the following would produce a basic aqueous solution? A) SO2 B) KCl C) NH4Cl D) none of these

D) none of these

Which factor listed below is most important in determining the strength of an oxyacid? A) the size of the molecule B) the ability of the molecule to change atomic orientation C) the identity of the central atom in the molecule D) the number of oxygen atoms present in the molecule

D) the number of oxygen atoms present in the molecule

The hydrogen halides (HF, HCl, HBr, and HI) are all polar molecules. The strength of the acid each forms in water is based on which of the following? A) the polarity of the molecule B) the size of the molecule C) the strength of the bond D) two of these

D) two of these

At 65°C, the ion-product constant of water, Kw, is 1.20 × 10-13. The pH of pure water at 65°C is: 7.000 6.560 5.880 6.460

D)6.460

Which of the following is the equilibrium constant expression for the dissociation of the weak acid HOCl? A) K= B) K = [H+][OCl-] C) K= D) K=

D)K=[H+][OCl-]/[HOCl]

As water is heated, its pH decreases. This means that: The water is no longer neutral.[H+] > [OH-][OH-] > [H+] None of these.

D)None of these.

Assuming that the value for K in the above reaction is greater than 1, this means that HF is a stronger acid than HOCl.

F