Question 1

What is the equilibrium concentration of H2C2O4 in a 0.370 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Accepted Answer

A) 2.5 × 10-1 M 
B) 1.4 × 10-1 M 
C) 3.7 × 10-1 M 
D) 5.1 × 10-5 M 
E) 1.2 × 10-1 M 
A) 2.5 × 10-1 M 
B) 1.4 × 10-1 M 
C) 3.7 × 10-1 M 
D) 5.1 × 10-5 M 
E) 1.2 × 10-1 M

Question 2

Which of the following salts will produce a neutral solution when added to pure water?

Accepted Answer

A) LiHCO3 
B) NH4NO3 
C) Na2SO4 
D) RbNO2 
E) KNO3 
A) LiHCO3 
B) NH4NO3 
C) Na2SO4 
D) RbNO2 
E) KNO3

Question 3

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (Ka =   )?

Accepted Answer

A) 2.17 
B) 7.00 
C) 1.87 
D) 12.13 
E) 5.13 
A) 2.17 
B) 7.00 
C) 1.87 
D) 12.13 
E) 5.13

Question 4

Consider the reaction NH3(aq)+ H2O(l)   NH4+(aq)+ OH-(aq).Kb for NH3 is 1.8 × 10-5 at 25°C.What is Ka for the NH4+ ion at 25°C?

Accepted Answer

A) 5.6 × 104 
B) 5.6 × 10-10 
C) 1.8 × 10-5 
D) 7.2 × 10-12 
E) 9.2 × 10-8 
A) 5.6 × 104 
B) 5.6 × 10-10 
C) 1.8 × 10-5 
D) 7.2 × 10-12 
E) 9.2 × 10-8

Question 5

The equilibrium hydronium ion concentration of an initially 0.510 M solution of a diprotic weak acid (H2A)is   M.What is Ka1? (assume Ca/Ka ≥ 102 and Ka1 >> Ka2)

Accepted Answer

A)    
B)    
C)    
D)    
E) not enough information provided 
A)    
B)    
C)    
D)    
E) not enough information provided

Question 6

What is the percent ionization of a 1.5 M HC2H3O2 solution (Ka = 1.8 × 10-5 )at 25°C?
+

Accepted Answer

A) 0.52 % 
B) 0.35 % 
C) 2.5 % 
D) 0.18 % 
E) 0.28 % 
A) 0.52 % 
B) 0.35 % 
C) 2.5 % 
D) 0.18 % 
E) 0.28 %

Question 7

A 0.10 M solution of a weak monoprotic acid has a hydronium-ion concentration of 7.2 × 10-4 M.What is the acid-ionization constant,Ka,for this acid?

Accepted Answer

A) 2.7 × 10-2 
B) 6.3 × 10-3 
C) 7.2 × 10-4 
D) 5.2 × 10-6 
E) 8.6 × 10-5 
A) 2.7 × 10-2 
B) 6.3 × 10-3 
C) 7.2 × 10-4 
D) 5.2 × 10-6 
E) 8.6 × 10-5

Question 8

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

Accepted Answer

A) K =   . 
B) K =   . 
C) K =   . 
D) K = [H+][NO2-]. 
E) none of these 
A) K =   . 
B) K =   . 
C) K =   . 
D) K = [H+][NO2-]. 
E) none of these

Question 9

Which of the following salts will produce an acidic solution when added to pure water?

Accepted Answer

A) Cs2CO3 
B) NaF 
C) KCN 
D) Al(NO3)3 
E) Li2S 
A) Cs2CO3 
B) NaF 
C) KCN 
D) Al(NO3)3 
E) Li2S

Question 10

A 0.010 M aqueous solution of a weak acid HA has a pH of 4.0.What is the degree of ionization of HA in the solution?

Accepted Answer

A) 0.1 % 
B) 0.01 % 
C) 0.001 % 
D) 1 % 
E) 10 % 
A) 0.1 % 
B) 0.01 % 
C) 0.001 % 
D) 1 % 
E) 10 %

Question 11

When equal volumes of solutions are mixed,as shown below,what will be the relative pH values of the resulting solutions?

Accepted Answer

A) I < V < III < II < IV 
B) V < I < IV < II < III 
C) III < I < IV = V < II 
D) I = V < III < II < IV 
E) III < I = V < III < IV < II 
A) I < V < III < II < IV 
B) V < I < IV < II < III 
C) III < I < IV = V < II 
D) I = V < III < II < IV 
E) III < I = V < III < IV < II

Question 12

Which of the following combinations is not suitable for making a buffer?

Accepted Answer

A) HClO4 and NaClO4 
B) NaH2PO4 and Na2HPO4 
C) NH4Cl and NH3 
D) H3PO4 and NaH2PO4 
E) Na2CO3 and NaHCO3 
A) HClO4 and NaClO4 
B) NaH2PO4 and Na2HPO4 
C) NH4Cl and NH3 
D) H3PO4 and NaH2PO4 
E) Na2CO3 and NaHCO3

Question 13

What is the concentration of HC2O4- in a 0.300 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Accepted Answer

A) 3.9× 10-3 M 
B) 1.0 × 10-1 M 
C) 1.3 × 10-1 M 
D) 3.9 × 10-3 M 
E) 5.1 × 10-5 M 
A) 3.9× 10-3 M 
B) 1.0 × 10-1 M 
C) 1.3 × 10-1 M 
D) 3.9 × 10-3 M 
E) 5.1 × 10-5 M

Question 14

What is the pH of a solution that is 0.048 M in HA and also 0.0032 M in NaA? (Ka = 4.1 × 10-6)

Accepted Answer

A) 8.06 
B) 4.21 
C) 6.56 
D) 5.39 
E) 7.76 
A) 8.06 
B) 4.21 
C) 6.56 
D) 5.39 
E) 7.76

Question 15

It is safe to make the simplifying assumption that x can be neglected in the denominator of the equilibrium equation when

Accepted Answer

A)    . 
B)    . 
C)    . 
D)    . 
E)    . 
A)    . 
B)    . 
C)    . 
D)    . 
E)    .

Question 16

A certain weak base B has a base-ionization constant Kb of 6.6 × 10-4 at 25°C.If strong acid is added to a solution of B,at what pH will [B] = [BH+]?

Accepted Answer

A) 8.5 
B) 10.8 
C) 7.0 
D) 3.2 
E) 5.5 
A) 8.5 
B) 10.8 
C) 7.0 
D) 3.2 
E) 5.5

Question 17

What is Kb for the following equilibrium? Ka for HNO2 is 5.0 × 10-4.
NO2-(aq)+ H2O(l)  
HNO2(aq)+ OH-(aq)

Accepted Answer

A) 2.0 × 10-4 
B) 5.0 × 10-4 
C) 5.0 × 1010 
D) 5.0 × 1018 
E) 2.0 × 10-11 
A) 2.0 × 10-4 
B) 5.0 × 10-4 
C) 5.0 × 1010 
D) 5.0 × 1018 
E) 2.0 × 10-11

Question 18

A 0.0678 M solution of a weak base has a pH of 9.44.What is the identity of the weak base?
Weak Base
Kb
Ethylamine (CH3CH2NH2)
4)7 × 10-4
Hydrazine (N2H4)
1)7 × 10-6
Hydroxylamine (NH2OH)
1)1 × 10-8
Pyridine (C5H5N)
1)4 × 10-9
Aniline (C6H5NH2)
4)2 × 10-10

Accepted Answer

A) hydrazine 
B) pyridine 
C) ethylamine 
D) hydroxylamine 
E) aniline 
A) hydrazine 
B) pyridine 
C) ethylamine 
D) hydroxylamine 
E) aniline

Question 19

What is the percent ionization at equilibrium in a 0.10 M solution of dimethylamine,(CH3)2NH (Kb = 5.1 × 10-4),at 25oC?

Accepted Answer

A) 6.8% 
B) 0.51% 
C) 0.68% 
D) 100% 
E) 10% 
A) 6.8% 
B) 0.51% 
C) 0.68% 
D) 100% 
E) 10%

Question 20

What is the concentration of HCO3- in a 0.010 M solution of carbonic acid,H2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.

Accepted Answer

A) 6.5 × 10-5 M 
B) 1.0 × 10-2 M 
C) 3.2 × 10-5 M 
D) 4.8 × 10-11 M 
E) 4.2 × 10-7 M 
A) 6.5 × 10-5 M 
B) 1.0 × 10-2 M 
C) 3.2 × 10-5 M 
D) 4.8 × 10-11 M 
E) 4.2 × 10-7 M

Exam 16: Acid-Base Equilibria

What is the equilibrium concentration of H2C2O4 in a 0.370 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

Which of the following salts will produce a neutral solution when added to pure water?

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (Ka = )?

Consider the reaction NH3(aq)+ H2O(l) NH4+(aq)+ OH-(aq).Kb for NH3 is 1.8 × 10-5 at 25°C.What is Ka for the NH4+ ion at 25°C?

The equilibrium hydronium ion concentration of an initially 0.510 M solution of a diprotic weak acid (H2A)is M.What is Ka1? (assume Ca/Ka ≥ 102 and Ka1 >> Ka2)

What is the percent ionization of a 1.5 M HC2H3O2 solution (Ka = 1.8 × 10-5 )at 25°C? +

A 0.10 M solution of a weak monoprotic acid has a hydronium-ion concentration of 7.2 × 10-4 M.What is the acid-ionization constant,Ka,for this acid?

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

Which of the following salts will produce an acidic solution when added to pure water?

A 0.010 M aqueous solution of a weak acid HA has a pH of 4.0.What is the degree of ionization of HA in the solution?

When equal volumes of solutions are mixed,as shown below,what will be the relative pH values of the resulting solutions?

Which of the following combinations is not suitable for making a buffer?

What is the concentration of HC2O4- in a 0.300 M oxalic acid,H2C2O4,solution? For oxalic acid,Ka1 = 5.6 × 10-2 and Ka2 = 5.1 × 10-5.

What is the pH of a solution that is 0.048 M in HA and also 0.0032 M in NaA? (Ka = 4.1 × 10-6)

It is safe to make the simplifying assumption that x can be neglected in the denominator of the equilibrium equation when

A certain weak base B has a base-ionization constant Kb of 6.6 × 10-4 at 25°C.If strong acid is added to a solution of B,at what pH will [B] = [BH+]?

What is Kb for the following equilibrium? Ka for HNO2 is 5.0 × 10-4. NO2-(aq)+ H2O(l) HNO2(aq)+ OH-(aq)

A 0.0678 M solution of a weak base has a pH of 9.44.What is the identity of the weak base? Weak Base Kb Ethylamine (CH3CH2NH2) 4)7 × 10-4 Hydrazine (N2H4) 1)7 × 10-6 Hydroxylamine (NH2OH) 1)1 × 10-8 Pyridine (C5H5N) 1)4 × 10-9 Aniline (C6H5NH2) 4)2 × 10-10

What is the percent ionization at equilibrium in a 0.10 M solution of dimethylamine,(CH3)2NH (Kb = 5.1 × 10-4),at 25oC?

What is the concentration of HCO3- in a 0.010 M solution of carbonic acid,H2CO3? For carbonic acid,Ka1 = 4.2 × 10-7 and Ka2 = 4.8 × 10-11.

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What is the equilibrium concentration of H₂C₂O₄ in a 0.370 M oxalic acid,H₂C₂O₄,solution? For oxalic acid,Ka₁ = 5.6 × 10^-2 and Ka₂ = 5.1 × 10^-5.

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (K_a = )?

Consider the reaction NH₃(aq)+ H₂O(l) NH₄⁺(aq)+ OH^-(aq).K_b for NH₃ is 1.8 × 10^-5 at 25°C.What is K_a for the NH₄⁺ ion at 25°C?

The equilibrium hydronium ion concentration of an initially 0.510 M solution of a diprotic weak acid (H₂A)is M.What is K_a1? (assume C_a/K_a ≥ 10² and K_a1 >> K_a2)

What is the percent ionization of a 1.5 M HC₂H₃O₂ solution (K_a = 1.8 × 10^-5 )at 25°C? +

A 0.10 M solution of a weak monoprotic acid has a hydronium-ion concentration of 7.2 × 10^-4 M.What is the acid-ionization constant,K_a,for this acid?

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

What is the concentration of HC₂O₄^- in a 0.300 M oxalic acid,H₂C₂O₄,solution? For oxalic acid,Ka₁ = 5.6 × 10^-2 and Ka₂ = 5.1 × 10^-5.

What is the pH of a solution that is 0.048 M in HA and also 0.0032 M in NaA? (K_a = 4.1 × 10^-6)

A certain weak base B has a base-ionization constant K_b of 6.6 × 10^-4 at 25°C.If strong acid is added to a solution of B,at what pH will [B] = [BH⁺]?

What is K_b for the following equilibrium? K_a for HNO₂ is 5.0 × 10^-4. NO₂^-(aq)+ H₂O(l) HNO₂(aq)+ OH^-(aq)

A 0.0678 M solution of a weak base has a pH of 9.44.What is the identity of the weak base? Weak Base K_b Ethylamine (CH₃CH₂NH₂) 4)7 × 10^-4 Hydrazine (N₂H₄) 1)7 × 10^-6 Hydroxylamine (NH₂OH) 1)1 × 10^-8 Pyridine (C₅H₅N) 1)4 × 10^-9 Aniline (C₆H₅NH₂) 4)2 × 10^-10

What is the percent ionization at equilibrium in a 0.10 M solution of dimethylamine,(CH₃)₂NH (K_b = 5.1 × 10^-4),at 25^oC?

What is the concentration of HCO₃^- in a 0.010 M solution of carbonic acid,H₂CO₃? For carbonic acid,Ka₁ = 4.2 × 10^-7 and Ka₂ = 4.8 × 10^-11.