Question 1

What is the value of Kb for the cyanide anion,CN-?
Ka(HCN)= 6.2 $\times$ 10-10

Accepted Answer

A) 1.6 $\times$ 10-4 
B) 1.6 $\times$ 10-5 
C) 3.8 $\times$ 10-4 
D) 3.8 $\times$ 10-5 
E) 6.2 $\times$ 104 
A) 1.6 $\times$ 10-4 
B) 1.6 $\times$ 10-5 
C) 3.8 $\times$ 10-4 
D) 3.8 $\times$ 10-5 
E) 6.2 $\times$ 104

Question 2

A 0.050 M solution of the weak acid HA has [H3O+] = 3.77 $\times$ 10-4 M.What is the Ka for the acid?

Accepted Answer

A) 7.5 $\times$ 10-3 M 
B) 2.8 $\times$ 10-6 M 
C) 7.0 $\times$ 10-7 M 
D) 7.0 $\times$ 10-8 M 
E) 2.6 $\times$ 10-11 M 
A) 7.5 $\times$ 10-3 M 
B) 2.8 $\times$ 10-6 M 
C) 7.0 $\times$ 10-7 M 
D) 7.0 $\times$ 10-8 M 
E) 2.6 $\times$ 10-11 M

Question 3

A solution is prepared by adding 0.10 mol of sodium sulfide,Na2S,to 1.00 L of water.Which statement about the solution is correct?

Accepted Answer

A) The solution is basic. 
B) The solution is neutral. 
C) The solution is acidic. 
D) The concentration of sodium ions and sulfide ions will be identical. 
E) The concentration of sulfide ions will be greater than the concentration of sodium ions. 
A) The solution is basic. 
B) The solution is neutral. 
C) The solution is acidic. 
D) The concentration of sodium ions and sulfide ions will be identical. 
E) The concentration of sulfide ions will be greater than the concentration of sodium ions.

Question 4

If a strong acid such as HCl is diluted sufficiently with water,the pH will be higher than 7.

Accepted Answer

A) True 
 B)False

Question 5

The substance H2SO3 is considered

Accepted Answer

A) a weak Arrhenius base. 
B) a strong Arrhenius acid. 
C) a strong Arrhenius base. 
D) a neutral compound. 
E) a weak Arrhenius acid. 
A) a weak Arrhenius base. 
B) a strong Arrhenius acid. 
C) a strong Arrhenius base. 
D) a neutral compound. 
E) a weak Arrhenius acid.

Question 6

What is the pH of a 0.20 M HCl solution?

Accepted Answer

A) < 0 
B) 0.70 
C) 1.61 
D) 12.39 
E) 13.30 
A) < 0 
B) 0.70 
C) 1.61 
D) 12.39 
E) 13.30

Question 7

What is the [H3O+] for a solution at 25°C that has pOH = 5.640?

Accepted Answer

A) 2.34 $\times$ 10-4 M 
B) 2.29 $\times$ 10-6 M 
C) 4.37 $\times$ 10-9 M 
D) 4.27 $\times$ 10-11 M 
E) 8.360 M 
A) 2.34 $\times$ 10-4 M 
B) 2.29 $\times$ 10-6 M 
C) 4.37 $\times$ 10-9 M 
D) 4.27 $\times$ 10-11 M 
E) 8.360 M

Question 8

A 0.15 M solution of chloroacetic acid has a pH of 1.86.What is the value of Ka for this acid?

Accepted Answer

A) 7.2 $\times$ 101 
B) 0.16 
C) 0.099 
D) 0.0014 
E) 0.00027 
A) 7.2 $\times$ 101 
B) 0.16 
C) 0.099 
D) 0.0014 
E) 0.00027

Question 9

What is the pH of a 0.0100 M sodium benzoate solution?
Kb (C7H5O2-)= 1.5 $\times$ 10-10

Accepted Answer

A) 0.38 
B) 5.91 
C) 8.09 
D) 9.82 
E) 13.62 
A) 0.38 
B) 5.91 
C) 8.09 
D) 9.82 
E) 13.62

Question 10

What is the pH of a 0.010 M triethanolammonium chloride, (HOC2H2)3NHCl,solution?
Kb, ((HOC2H2)3N)= 5.9 $\times$ 10-7

Accepted Answer

A) 2.75 
B) 4.89 
C) 9.11 
D) 11.25 
E) None of these choices is correct. 
A) 2.75 
B) 4.89 
C) 9.11 
D) 11.25 
E) None of these choices is correct.

Question 11

Farmers who raise cotton once used arsenic acid,H3AsO4,as a defoliant at harvest time.Arsenic acid is a polyprotic acid with K1 = 2.5 $\times$ 10-4,K2 = 5.6 $\times$ 10-8,and K3 = 3 $\times$ 10-13.What is the pH of a 0.500 M solution of arsenic acid?

Accepted Answer

A) 0.85 
B) 1.96 
C) 3.90 
D) 4.51 
E) None of these choices is correct. 
A) 0.85 
B) 1.96 
C) 3.90 
D) 4.51 
E) None of these choices is correct.

Question 12

All weak acids have strong conjugate bases.

Accepted Answer

A) True 
 B)False

Question 13

Arsenic acid,H3AsO4,is used industrially to manufacture insecticides.Arsenic acid is a polyprotic acid with K1 = 2.5 $\times$ 10-4,K2 = 5.6 $\times$ 10-8,and K3 = 3 $\times$ 10-13.What is the concentration of the HAsO42- in a solution whose initial arsenic acid concentration was 0.35 M?

Accepted Answer

A) 9.4 $\times$ 10-3 M 
B) 2.5 $\times$ 10-4 M 
C) 8.8 $\times$ 10-5 M 
D) 5.6 $\times$ 10-8 M 
E) None of these choices is correct. 
A) 9.4 $\times$ 10-3 M 
B) 2.5 $\times$ 10-4 M 
C) 8.8 $\times$ 10-5 M 
D) 5.6 $\times$ 10-8 M 
E) None of these choices is correct.

Question 14

Which one of the following substances will give an aqueous solution of pH < 7?

Accepted Answer

A) KI 
B) NH4Br 
C) Na2CO3 
D) CH3COONa 
E) CH3OH 
A) KI 
B) NH4Br 
C) Na2CO3 
D) CH3COONa 
E) CH3OH

Question 15

Formic acid,which is a component of insect venom,has a Ka = 1.8 $\times$ 10-4.What is the [H3O+] in a solution that is initially 0.10 M formic acid,HCOOH?

Accepted Answer

A) 4.2 $\times$ 10-3 M 
B) 8.4 $\times$ 10-3 M 
C) 1.8 $\times$ 10-4 M 
D) 1.8 $\times$ 10-5 M 
E) 1.8 $\times$ 10-6 M 
A) 4.2 $\times$ 10-3 M 
B) 8.4 $\times$ 10-3 M 
C) 1.8 $\times$ 10-4 M 
D) 1.8 $\times$ 10-5 M 
E) 1.8 $\times$ 10-6 M

Question 16

A student adds 0.1 mol of oxalic acid and 0.1 mol of sodium dihydrogen phosphate to enough water to make 1.0 L of solution.The following equilibrium is established with the concentrations of the products greater than the concentrations of the reactants.Which of the statements about the equilibrium system is correct?
H2C2O4(aq)+ H2PO4-(aq)  
HC2O4-(aq)+ H3PO4(aq)

Accepted Answer

A) Oxalic acid is a weaker acid than phosphoric acid. 
B) The hydrogen oxalate anion,HC2O4-,is a stronger base than the dihydrogen phosphate anion,H2PO4-. 
C) Phosphoric acid is a weaker acid than oxalic acid. 
D) The dihydrogen phosphate anion,H2PO4-,is a stronger acid than oxalic acid. 
E) Water is a stronger acid than either oxalic or phosphoric acids. 
A) Oxalic acid is a weaker acid than phosphoric acid. 
B) The hydrogen oxalate anion,HC2O4-,is a stronger base than the dihydrogen phosphate anion,H2PO4-. 
C) Phosphoric acid is a weaker acid than oxalic acid. 
D) The dihydrogen phosphate anion,H2PO4-,is a stronger acid than oxalic acid. 
E) Water is a stronger acid than either oxalic or phosphoric acids.

Question 17

A solution of sodium acetate (CH3COONa)in water is weakly basic.

Accepted Answer

A) True 
 B)False

Question 18

According to Brønsted and Lowry,which one of the following is not a conjugate acid-base pair?

Accepted Answer

A) H3O+/OH- 
B) CH3OH2+/CH3OH 
C) HI/I- 
D) HSO4-/SO42- 
E) H2/H- 
A) H3O+/OH- 
B) CH3OH2+/CH3OH 
C) HI/I- 
D) HSO4-/SO42- 
E) H2/H-

Question 19

Which of the following pairs has the stronger acid listed first?

Accepted Answer

A) HBr,HI 
B) HClO2,HClO3 
C) H2SeO4,H2SeO3 
D) HNO2,HNO3 
E) HF,HCl 
A) HBr,HI 
B) HClO2,HClO3 
C) H2SeO4,H2SeO3 
D) HNO2,HNO3 
E) HF,HCl

Question 20

What is the pH of a 0.050 M HBr solution?

Accepted Answer

A) 0.89 
B) 1.12 
C) 1.30 
D) 3.00 
E) None of these choices is correct. 
A) 0.89 
B) 1.12 
C) 1.30 
D) 3.00 
E) None of these choices is correct.

Exam 18: Acid-Base Equilibria

What is the value of Kb for the cyanide anion,CN-? Ka(HCN)= 6.2 ×\times× 10-10

A 0.050 M solution of the weak acid HA has [H3O+] = 3.77 ×\times× 10-4 M.What is the Ka for the acid?

A solution is prepared by adding 0.10 mol of sodium sulfide,Na2S,to 1.00 L of water.Which statement about the solution is correct?

If a strong acid such as HCl is diluted sufficiently with water,the pH will be higher than 7.

The substance H2SO3 is considered

What is the pH of a 0.20 M HCl solution?

What is the [H3O+] for a solution at 25°C that has pOH = 5.640?

A 0.15 M solution of chloroacetic acid has a pH of 1.86.What is the value of Ka for this acid?

What is the pH of a 0.0100 M sodium benzoate solution? Kb (C7H5O2-)= 1.5 ×\times× 10-10

What is the pH of a 0.010 M triethanolammonium chloride, (HOC2H2)3NHCl,solution? Kb, ((HOC2H2)3N)= 5.9 ×\times× 10-7

Farmers who raise cotton once used arsenic acid,H3AsO4,as a defoliant at harvest time.Arsenic acid is a polyprotic acid with K1 = 2.5 ×\times× 10-4,K2 = 5.6 ×\times× 10-8,and K3 = 3 ×\times× 10-13.What is the pH of a 0.500 M solution of arsenic acid?

All weak acids have strong conjugate bases.

Arsenic acid,H3AsO4,is used industrially to manufacture insecticides.Arsenic acid is a polyprotic acid with K1 = 2.5 ×\times× 10-4,K2 = 5.6 ×\times× 10-8,and K3 = 3 ×\times× 10-13.What is the concentration of the HAsO42- in a solution whose initial arsenic acid concentration was 0.35 M?

Which one of the following substances will give an aqueous solution of pH < 7?

Formic acid,which is a component of insect venom,has a Ka = 1.8 ×\times× 10-4.What is the [H3O+] in a solution that is initially 0.10 M formic acid,HCOOH?

A solution of sodium acetate (CH3COONa)in water is weakly basic.

According to Brønsted and Lowry,which one of the following is not a conjugate acid-base pair?

Which of the following pairs has the stronger acid listed first?

What is the pH of a 0.050 M HBr solution?

Keys to the Study of Chemistry

The Components of Matter

Stoichiometry of Formulas and Equations

Three Major Classes of Chemical Reactions

Gases and the Kinetic-Molecular Theory

Thermochemistry: Energy Flow and Chemical Change

Quantum Theory and Atomic Structure

Electron Configuration and Chemical Periodicity

Models of Chemical Bonding

The Shapes of Molecules

Theories of Covalent Bonding

Intermolecular Forces: Liquids,solids,and Phase Changes

The Properties of Solutions

The Main-Group Elements: Applying Principles of Bonding and Structure

Organic Compounds and the Atomic Properties of Carbon

Kinetics: Rates and Mechanisms of Chemical Reactions

Equilibrium: the Extent of Chemical Reactions

Ionic Equilibria in Aqueous Systems

Thermodynamics: Entropy, free Energy, and the Direction of Chemical Reactions

Electrochemistry: Chemical Change and Electrical Work

The Transition Elements and Their Coordination Compounds

Nuclear Reactions and Their Applications

Filters

What is the value of K_b for the cyanide anion,CN^-? K_a(HCN)= 6.2 $\times$ 10^-10

A 0.050 M solution of the weak acid HA has [H₃O⁺] = 3.77 $\times$ 10^-4 M.What is the K_a for the acid?

A solution is prepared by adding 0.10 mol of sodium sulfide,Na₂S,to 1.00 L of water.Which statement about the solution is correct?

The substance H₂SO₃ is considered

What is the [H₃O⁺] for a solution at 25°C that has pOH = 5.640?

A 0.15 M solution of chloroacetic acid has a pH of 1.86.What is the value of K_a for this acid?

What is the pH of a 0.0100 M sodium benzoate solution? K_b (C₇H₅O₂^-)= 1.5 $\times$ 10^-10

What is the pH of a 0.010 M triethanolammonium chloride, (HOC₂H₂)₃NHCl,solution? K_b, ((HOC₂H₂)₃N)= 5.9 $\times$ 10^-7

Farmers who raise cotton once used arsenic acid,H₃AsO₄,as a defoliant at harvest time.Arsenic acid is a polyprotic acid with K₁ = 2.5 $\times$ 10^-4,K₂ = 5.6 $\times$ 10^-8,and K₃ = 3 $\times$ 10^-13.What is the pH of a 0.500 M solution of arsenic acid?

Formic acid,which is a component of insect venom,has a K_a = 1.8 $\times$ 10^-4.What is the [H₃O⁺] in a solution that is initially 0.10 M formic acid,HCOOH?

A solution of sodium acetate (CH₃COONa)in water is weakly basic.