Question 1

Hydrofluoric acid has a pKa value of 3.14.What is the value of pKb for fluoride ion?

Accepted Answer

A)  1.4 × 10-11 
B)  7.2 × 10-4 
C)  3.14 
D)  10.86 
E)  17.14 
A)  1.4 × 10-11 
B)  7.2 × 10-4 
C)  3.14 
D)  10.86 
E)  17.14

Question 2

Arrange the following acids in order of decreasing acid strength in aqueous solution: HBr,HOCl,HOBr,and HOI.

Accepted Answer

A)  HBr > HClO > HBrO > HIO 
B)  HIO > HBrO > HClO > HBr 
C)  HBr > HIO > HBrO > HClO 
D)  HClO > HBr > HBrO > HIO 
E)  HClO > HBrO > HBr > HIO 
A)  HBr > HClO > HBrO > HIO 
B)  HIO > HBrO > HClO > HBr 
C)  HBr > HIO > HBrO > HClO 
D)  HClO > HBr > HBrO > HIO 
E)  HClO > HBrO > HBr > HIO

Question 3

All of the following species behave as Lewis acids EXCEPT ____.

Accepted Answer

A)  BH3 
B)  Al3+ 
C)  SO2 
D)  Al(OH)3 
E)  NH3 
A)  BH3 
B)  Al3+ 
C)  SO2 
D)  Al(OH)3 
E)  NH3

Question 4

Identify from the following list of molecules and ions which behave as Lewis acids: CO2,NH3,BCl3,and Fe3+.

Accepted Answer

A)  CO2 and NH3 
B)  NH3 and BCl3 
C)  CO2 and Fe3+ 
D)  CO2,BCl3,and Fe3+ 
E)  CO2,NH3,BCl3,and Fe3+ 
A)  CO2 and NH3 
B)  NH3 and BCl3 
C)  CO2 and Fe3+ 
D)  CO2,BCl3,and Fe3+ 
E)  CO2,NH3,BCl3,and Fe3+

Question 5

What is Ka at 25°C for the following equilibrium given Kb (CH3NH2)= 4.4 × 10-4 at 25°C.? CH3NH3+(aq)+ H2O(l)   CH3NH2(aq)+ H3O+(aq)

Accepted Answer

A)  4.4 × 10-4 
B)  2.3 × 103 
C)  4.4 × 10-10 
D)  4.4 × 104 
E)  2.3 × 10-11 
A)  4.4 × 10-4 
B)  2.3 × 103 
C)  4.4 × 10-10 
D)  4.4 × 104 
E)  2.3 × 10-11

Question 6

What is the equilibrium pH of an initially 4.9 M solution of hypoiodous acid,HOI,at 25°C (Ka =   ; Kw = 1.01 × 10-14)?

Accepted Answer

A)  4.97 
B)  7.00 
C)  5.12 
D)  4.82 
E)  8.34 
A)  4.97 
B)  7.00 
C)  5.12 
D)  4.82 
E)  8.34

Question 7

What is the conjugate base of [Fe(H2O)6]3+(aq)?

Accepted Answer

A)  H3O+ 
B)  [Fe(H2O)6]2+ 
C)  [Fe(H2O)5H3O]4+ 
D)  [Fe(H2O)5OH]2+ 
E)  [Fe(H2O)5]3+ 
A)  H3O+ 
B)  [Fe(H2O)6]2+ 
C)  [Fe(H2O)5H3O]4+ 
D)  [Fe(H2O)5OH]2+ 
E)  [Fe(H2O)5]3+

Question 8

What is the pH of the solution that results from mixing 75 mL of 0.50 M NH3(aq)and 75 mL of 0.50 HCl(aq)at 25 °C? (Kb for NH3 = 1.8 × 10-5)

Accepted Answer

A)  0.60 
B)  2.67 
C)  4.74 
D)  4.93 
E)  9.26 
A)  0.60 
B)  2.67 
C)  4.74 
D)  4.93 
E)  9.26

Question 9

Which of the following is the correct hydroxide ion (OH-)concentration of an aqueous solution with a pH of 2.77? (Kw = 1.01 × 10-14)

Accepted Answer

A)  5.9 × 10-12 M 
B)  1.7 × 10-3 M 
C)  5.2 × 10-2 M 
D)  1.1 × 101 M 
E)  5.9 × 102 M 
A)  5.9 × 10-12 M 
B)  1.7 × 10-3 M 
C)  5.2 × 10-2 M 
D)  1.1 × 101 M 
E)  5.9 × 102 M

Question 10

What is the pH of a 0.42 M solution of sodium propionate,NaC3H5O2,at 25°C? (propionic acid,HC3H5O2,is monoprotic and has a Ka = 1.3 × 10-5 at 25°C..Kw = 1.01 × 10-14 )

Accepted Answer

A)  6.06 
B)  4.75 
C)  11.10 
D)  7.94 
E)  9.25 
A)  6.06 
B)  4.75 
C)  11.10 
D)  7.94 
E)  9.25

Question 11

According to the Brønsted-Lowry definition,a base

Accepted Answer

A)  increases the OH- concentration in an aqueous solution. 
B)  is a strong electrolyte. 
C)  is a proton acceptor. 
D)  increases the pH of a solution. 
E)  is a proton donor. 
A)  increases the OH- concentration in an aqueous solution. 
B)  is a strong electrolyte. 
C)  is a proton acceptor. 
D)  increases the pH of a solution. 
E)  is a proton donor.

Question 12

The concentration of H3O+ in a solution is 5 × 10-4 M at 25°C.What is its hydroxide-ion concentration? (Kw = 1.01 × 10-14)

Accepted Answer

A)  5 × 10-4 M 
B)  2 × 10-10 M 
C)  3 × 10-10 M 
D)  4 × 10-10 M 
E)  2 × 10-11 M 
A)  5 × 10-4 M 
B)  2 × 10-10 M 
C)  3 × 10-10 M 
D)  4 × 10-10 M 
E)  2 × 10-11 M

Question 13

What is the hydroxide-ion concentration in a 0.10 M solution of Na2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.(Kw = 1.0 × 10-14)

Accepted Answer

A)  4.6 × 10-3 M 
B)  2.0 × 10-4 M 
C)  4.9 × 10-5 M 
D)  4.2 × 10-9 M 
E)  2.2 × 10-6 M 
A)  4.6 × 10-3 M 
B)  2.0 × 10-4 M 
C)  4.9 × 10-5 M 
D)  4.2 × 10-9 M 
E)  2.2 × 10-6 M

Question 14

Given that Ka for the weak acid HA is 3.49 × 10-8,calculate K for the reaction of HA with OH-. HA(aq)+ OH−(aq)D A−(aq)+ H2O(   )

Accepted Answer

A)  3.49 
B)  3.49 × 106 
C)  3.49 × 10-22 
D)  2.87 × 1021 
E)  2.87 × 10-7 
A)  3.49 
B)  3.49 × 106 
C)  3.49 × 10-22 
D)  2.87 × 1021 
E)  2.87 × 10-7

Question 15

Given the following acid dissociation constants: Ka (H3PO4)= 7.5 × 10-3
Ka (NH4+)= 5.6 × 10-10
Determine the equilibrium constant for the reaction below at 25 °C.
H3PO4(aq)+ NH3(aq)   NH4+(aq)+ H2PO4−(aq)

Accepted Answer

A)  4.2 × 10-12 
B)  7.5 × 10-8 
C)  4.2 × 102 
D)  1.3 × 107 
E)  2.4 × 1011 
A)  4.2 × 10-12 
B)  7.5 × 10-8 
C)  4.2 × 102 
D)  1.3 × 107 
E)  2.4 × 1011

Exam 17: Principles of Chemical Reactivity: the Chemistry of Acids and Bases

Hydrofluoric acid has a pKa value of 3.14.What is the value of pKb for fluoride ion?

Arrange the following acids in order of decreasing acid strength in aqueous solution: HBr,HOCl,HOBr,and HOI.

All of the following species behave as Lewis acids EXCEPT ____.

Identify from the following list of molecules and ions which behave as Lewis acids: CO2,NH3,BCl3,and Fe3+.

What is Ka at 25°C for the following equilibrium given Kb (CH3NH2)= 4.4 × 10-4 at 25°C.? CH3NH3+(aq)+ H2O(l) CH3NH2(aq)+ H3O+(aq)

What is the equilibrium pH of an initially 4.9 M solution of hypoiodous acid,HOI,at 25°C (Ka = ; Kw = 1.01 × 10-14)?

What is the conjugate base of [Fe(H2O)6]3+(aq)?

What is the pH of the solution that results from mixing 75 mL of 0.50 M NH3(aq)and 75 mL of 0.50 HCl(aq)at 25 °C? (Kb for NH3 = 1.8 × 10-5)

Which of the following is the correct hydroxide ion (OH-)concentration of an aqueous solution with a pH of 2.77? (Kw = 1.01 × 10-14)

What is the pH of a 0.42 M solution of sodium propionate,NaC3H5O2,at 25°C? (propionic acid,HC3H5O2,is monoprotic and has a Ka = 1.3 × 10-5 at 25°C..Kw = 1.01 × 10-14 )

According to the Brønsted-Lowry definition,a base

The concentration of H3O+ in a solution is 5 × 10-4 M at 25°C.What is its hydroxide-ion concentration? (Kw = 1.01 × 10-14)

What is the hydroxide-ion concentration in a 0.10 M solution of Na2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.(Kw = 1.0 × 10-14)

Given that Ka for the weak acid HA is 3.49 × 10-8,calculate K for the reaction of HA with OH-. HA(aq)+ OH−(aq)D A−(aq)+ H2O( )

Given the following acid dissociation constants: Ka (H3PO4)= 7.5 × 10-3 Ka (NH4+)= 5.6 × 10-10 Determine the equilibrium constant for the reaction below at 25 °C. H3PO4(aq)+ NH3(aq) NH4+(aq)+ H2PO4−(aq)

Basic Concepts of Chemistry

Lets Review: The Tools of Quantitative Chemistry

Atoms, molecules, and Ions

Chemical Reactions

Stoichiometry: Quantitative Information About Chemical Reactions

Principles of Chemical Reactivity: Energy and Chemical Reactions

The Structure of Atoms

The Structure of Atoms and Periodic Trends

Bonding and Molecular Structure

Bonding and Molecular Structure Orbital Hybridization and Molecular Orbitals

Gases and Their Properties

Intermolecular Forces and Liquids

The Solid State

Solutions and Their Behavior

Chemical Kinetics: the Rates of Chemical Reactions

Principles of Chemical Reactivity: Equilibria

Principles of Chemical Reactivity: Other Aspects of Aqueous Equilibria

Principles of Chemical Reactivity: Entropy and Free Energy

Principles of Chemical Reactivity: Electron Transfer Reactions

Environmental Chemistry: Earths Environment, energy, and Sustainability

The Chemistry of the Main Group Elements

The Chemistry of the Transition Elements

Carbon: Not Just Another Element

Biochemistry

Nuclear Chemistry

Filters

Hydrofluoric acid has a pK_a value of 3.14.What is the value of pK_b for fluoride ion?

Identify from the following list of molecules and ions which behave as Lewis acids: CO₂,NH₃,BCl₃,and Fe³⁺.

What is K_a at 25°C for the following equilibrium given K_b (CH₃NH₂)= 4.4 × 10^-4 at 25°C.? CH₃NH₃⁺(aq)+ H₂O(l) CH₃NH₂(aq)+ H₃O⁺(aq)

What is the equilibrium pH of an initially 4.9 M solution of hypoiodous acid,HOI,at 25°C (K_a = ; K_w = 1.01 × 10^-14)?

What is the conjugate base of [Fe(H₂O)₆]³⁺(aq)?

What is the pH of the solution that results from mixing 75 mL of 0.50 M NH₃(aq)and 75 mL of 0.50 HCl(aq)at 25 °C? (K_b for NH₃ = 1.8 × 10^-5)

Which of the following is the correct hydroxide ion (OH^-)concentration of an aqueous solution with a pH of 2.77? (K_w = 1.01 × 10^-14)

What is the pH of a 0.42 M solution of sodium propionate,NaC₃H₅O₂,at 25°C? (propionic acid,HC₃H₅O₂,is monoprotic and has a K_a = 1.3 × 10^-5 at 25°C..K_w = 1.01 × 10^-14 )

The concentration of H₃O⁺ in a solution is 5 × 10^-4 M at 25°C.What is its hydroxide-ion concentration? (K_w = 1.01 × 10^-14)

What is the hydroxide-ion concentration in a 0.10 M solution of Na₂CO₃? For carbonic acid,K_a1 = 4.2 × 10^-7 and K_a2 = 4.8 × 10^-11.(K_w = 1.0 × 10^-14)

Given that K_a for the weak acid HA is 3.49 × 10^-8,calculate K for the reaction of HA with OH^-. HA(aq)+ OH−(aq)D A−(aq)+ H₂O( )

Given the following acid dissociation constants: K_a (H₃PO₄)= 7.5 × 10^-3 K_a (NH₄⁺)= 5.6 × 10^-10 Determine the equilibrium constant for the reaction below at 25 °C. H₃PO₄(aq)+ NH₃(aq) NH₄⁺(aq)+ H₂PO₄−(aq)