Name: 
 

Acid and Base Equilibria: Ka, Kb, pH, pOH and Buffers


Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
What is the conjugate acid of NH3?
a.
NH3
b.
NH2+
c.
NH3+
d.
NH4+
e.
NH4OH
 

 2. 
The conjugate base of HSO4- is __________.
a.
OH-
b.
H2SO4
c.
SO42-
d.
HSO4+
e.
H3SO4+
 

 3. 
The conjugate acid of HSO4- is  __________.
a.
SO42-
b.
H2SO4
c.
HSO4+
d.
H+
e.
HSO3+
 

 4. 
What is the conjugate base of OH-?
a.
O2
b.
O-
c.
H2O
d.
O2-
e.
H3O+
 

 5. 
What is the pH of an aqueous solution at 25.0 °C in which [H+] is 0.0025 M?
a.
3.40
b.
2.60
c.
-2.60
d.
-3.40
e.
2.25
 

 6. 
What is the pH of an aqueous solution at 25.0 °C in which [OH-] is 0.0025 M?
a.
+2.60
b.
-2.60
c.
+11.4
d.
-11.4
e.
-2.25
 

 7. 
What is the pH of an aqueous solution at 25.0 °C that contains 3.98 ´ 10-9 M hydronium ion?
a.
8.400
b.
5.600
c.
9.000
d.
3.980
e.
7.000
 

 8. 
What is the pH of an aqueous solution at 25.0 °C that contains 3.98 ´ 10-9 M hydroxide ion?
a.
8.40
b.
5.60
c.
9.00
d.
3.98
e.
7.00
 

 9. 
An aqueous solution contains 0.100 M NaOH at 25.0°C.  The pH of the solution is __________.
a.
0.100
b.
1.00
c.
13.00
d.
7.00
e.
-1.00
 

 10. 
HZ is a weak acid. An aqueous solution of HZ is prepared by dissolving 0.020 mol of HZ in sufficient water to yield 1.0 L of solution. The pH of the solution was 4.93 at 25.0°C. The Ka of HZ is __________.
a.
1.2 ´ 10-5
b.
6.9 ´ 10-9
c.
1.4 ´ 10-10
d.
9.9 ´ 10-2
e.
2.8 ´ 10-12
 

 11. 
The pH of a 0.55 M aqueous solution of hypobromous acid, HBrO, at 25.0°C is 4.48. What is the value of Ka for HBrO?
a.
2.0 ´ 10-9
b.
1.1 ´ 10-9
c.
6.0 ´ 10-5
d.
3.3 ´ 10-5
e.
3.0 ´ 104
 

 12. 
The Ka of hydrofluoric acid (HF) at 25.0°C is 6.8 ´ 10-4. What is the pH of a 0.35 M aqueous solution of HF?
a.
3.25
b.
1.81
c.
3.64
d.
0.46
e.
1.22
 

 13. 
Determine the pH of a 0.35 M aqueous solution of CH3NH2 (methylamine). The Kb of methylamine is 4.4 ´ 10-4.
a.
10.00
b.
3.86
c.
12.09
d.
1.96
e.
13.24
 

 14. 
The Ka for HCN is 4.9 ´ 10-10. What is the value of Kb for CN-?
a.
2.0 ´ 10-5
b.
4.0 ´ 10-6
c.
4.9 ´ 104
d.
4.9 ´ 10-24
e.
2.0 ´ 109
 

 15. 
The pH of a 0.15 M aqueous solution of NaZ (the sodium salt of HZ) is 10.7. What is the Ka for HZ?
a.
1.6 ´ 10-6
b.
6.0 ´ 10-9
c.
8.9 ´ 10-4
d.
1.3 ´ 10-12
e.
3.3 ´ 10-8
 

 16. 
According to the Arrhenius concept, an acid is a substance that __________.
a.
is capable of donating one or more H+
b.
causes an increase in the concentration of H+ in aqueous solutions
c.
can accept a pair of electrons to form a coordinate covalent bond
d.
reacts with the solvent to form the cation formed by autoionization of that solvent
e.
tastes bitter
 

 17. 
A Brmc017-1.jpgnsted-Lowry base is defined as a substance that __________.
a.
increases [H+] when placed in H2O
b.
decreases [H+] when placed in H2O
c.
increases [OH-] when placed in H2O
d.
acts as a proton acceptor
e.
acts as a proton donor
 

 18. 
A Brmc018-1.jpgnsted-Lowry acid is defined as a substance that __________.
a.
increases  Ka when placed in H2O
b.
decreases [H+] when placed in H2O
c.
increases [OH-] when placed in H2O
d.
acts as a proton acceptor
e.
acts as a proton donor
 

 19. 
A substance that is capable of acting as both an acid and as a base is __________.
a.
autosomal
b.
conjugated
c.
amphoteric
d.
saturated
e.
miscible
 

 20. 
The molar concentration of hydronium ion in pure water at 25°C is __________.
a.
0.00
b.
1.0 ´ 10-7
c.
1.0 ´ 10-14
d.
1.00
e.
7.00
 

 21. 
The magnitude of Kw indicates that __________.
a.
water autoionizes very slowly
b.
water autoionizes very quickly
c.
water autoionizes only to a very small extent
d.
the autoionization of water is exothermic
 

 22. 
In basic solution, __________.
a.
[H3O+] = [OH-]
b.
[H3O+] > [OH-]
c.
[H3O+] < [OH-]
d.
[H3O+] = 0 M
e.
[OH-] > 7.00
 

 23. 
Which solution below has the highest concentration of hydroxide ions?
a.
pH = 3.21
b.
pH = 12.6
c.
pH = 7.93
d.
pH = 9.82
e.
pH = 7.00
 

 24. 
Nitric acid is a strong acid.  This means that __________.
a.
aqueous solutions of HNO3 contain equal concentrations of H+(aq) and OH-(aq)
b.
HNO3 does not dissociate at all when it is dissolved in water
c.
HNO3 dissociates completely to H+(aq) and NO3-(aq) when it dissolves in water
d.
HNO3 produces a gaseous product when it is neutralized
e.
HNO3 cannot be neutralized by a weak base
 

 25. 
Of the following acids, __________ is not a strong acid.
a.
HNO2
b.
H2SO4
c.
HNO3
d.
HClO4
e.
HCl
 

 26. 
Of the following, __________ is a weak acid.
a.
HF
b.
HCl
c.
HBr
d.
HNO3
e.
HClO4
 

 27. 
Which one of the following is the weakest acid?
a.
HF (Ka = 6.8 ´ 10-4)
b.
HClO (Ka = 3.0 ´ 10-8)
c.
HNO2 (Ka = 4.5 ´ 10-4)
d.
HCN (Ka = 4.9 ´ 10-10)
e.
Acetic acid (Ka = 1.8 ´ 10-5)
 

 28. 
Of the acids in the table below, __________ is the strongest acid.

mc028-1.jpg
a.
HOAc
b.
HCHO2
c.
HClO
d.
HF
e.
HOAc and HCHO2
 

 29. 
The Ka of hypochlorous acid (HClO) is 3.0 ´ 10-8 at 25.0°C . What is the % ionization of hypochlorous acid in a 0.015 M aqueous solution of HClO at 25.0°C?
a.
4.5 ´ 10-8
b.
14
c.
2.1 ´ 10-5
d.
0.14
e.
1.4 ´ 10-3
 

 30. 
Which one of the following is a BrÆnsted-Lowry acid?
a.
(CH3)3NH+
b.
CH3COOH
c.
HF
d.
HNO2
e.
all of the above
 

 31. 
Classify the following compounds as weak acids (W) or strong acids (S):

benzoic acidnitric acidacetic acid
a.
W W W
b.
S  S  S
c.
S W W
d.
W S S
e.
W S W
 

 32. 
Classify the following compounds as weak acids (W) or strong acids (S):

nitrous acidhydrochloric acidhydrofluoric acid
a.
W W W
b.
S  S  S
c.
S W W
d.
W S S
e.
W S W
 

 33. 
Using the data in the table, which of the conjugate bases below is the strongest base?

mc033-1.jpg
a.
OAc-
b.
C7H5O2-
c.
NO2-
d.
F-
e.
OAc- and C7H5O2-
 

 34. 
Using the data in the table, which of the conjugate bases below is the weakest base?

mc034-1.jpg
a.
OAc-
b.
CHO2-
c.
ClO-
d.
F-
e.
OAc- and CHO2-
 

 35. 
Which of the following aqueous solutions has the lowest [OH-]?
a.
a solution with a pH of 3.0
b.
a 1 ´ 10-4 M solution of HNO3
c.
a solution with a pOH of 12.0
d.
pure water
e.
a 1 ´ 10-3 M solution of NH4Cl
 

 36. 
Of the compounds below, a 0.1 M aqueous solution of __________ will have the highest pH.
a.
KCN, Ka of HCN = 4.0 ´ 10-10
b.
NH4NO3, Kb of NH3 = 1.8 ´ 10-5
c.
NaOAc, Ka of HOAc = 1.8 ´ 10-5
d.
NaClO, Ka of HClO = 3.2 ´ 10-8
e.
NaHS, Kb of HS- = 1.8 ´ 10-7
 

 37. 
In the gas phase reaction below, NH3 is acting as a(n) __________ base but not as a(n) __________ base.

mc037-1.jpg
a.
Arrhenius, BrÆnsted-Lowry
b.
BrÆnsted-Lowry, Lewis
c.
Lewis, Arrhenius
d.
Lewis, BrÆnsted-Lowry
e.
Arrhenius, Lewis
 



 
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