NAME _________________________________________
PRE-QUIZ FOR QUEST 2 ACID/BASE
DIRECTIONS: I took a number of these questions from around the web. Not all are like AP questions – but I
feel that these will certainly give you a run for your review money. I am attacking your review in this fashion –
because I want you to hear another voice … and this may do the trick. The answers are on the last pages.
1. Which of the following does NOT represent an acid followed by its conjugate base?
1) H3O+ / H2O
2) HCN / CN3) HCl / Cl4) HC2H3O2 / OH5) All are acids followed by their conjugate base
2. According to the Bronsted-Lowry definition, a base is
1) a substance that increases the hydroxide ion concentration of a solution
2) a substance that can accept a proton from an acid
3) a substance that can donate an electron pair to the formation of a covalent bond
4) a substance that increases the anion formed by the autoionization of the solvent
5) a substance that donates a proton
3. The equilibrium constant for the reaction A- + H+  HA is called:
1) Ka
2) Kb
3) 1/Ka
4) Kw/Kb
5) KwKa
4. At 0°C the Kw for water is 1.2 x 10-15. The pH of pure water at this temperature is
1) 7.00
2) 6.88
3) 7.56
4) 7.46
5) none of these
5. Given HCN(aq) + HCO3-(aq)  CN-(aq) + H2CO3(aq)
If K< 1, what is the strongest base in this system?
1) HCN
2) HCO33) CN4) H2CO3
5) H2O
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6. The following acids are listed in order of decreasing acid strength in water.
HI > HNO2 > CH3COOH > HClO > HCN
According to Bronsted-Lowry theory, which of the following ions is the weakest base?
1) I2) NO23) CH3COO4) ClO5) CN7. Which of the following is an acid?
1) HCOOH
2) CH3OH
3) KOH
4) NH3
5) CH3NH2
8. What is the strongest acid?
1) HClO2
2) HClO3
3) HClO4
4) HF
5) HOCl
9. Which of the following reactions does not proceed significantly to the right in aqueous solution?
1) HCl + H2O → H3O+ + Cl2) H3O+ + OH- → 2H2O
3) H2O + HSO4- → H2SO4 + OH4) HCN + OH- → H2O + CN5) H2SO4 + H2O → H3O+ + HSO410. What is the [H+] in a solution which shows a pH of 2.30?
1) 2.3M
2) 11.7M
3) 5.0 x 10-3M
4) 2.0 x 10-12M
5) none of these
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11. What is the pH of a solution at 25 degrees Celsius in which [OH-] = 3.4 x 10-5 M.
1) 4.5
2) 10.5
3) 9.5
4) 6.3
5) none of these
12. What is the pH of a 10.0 M solution of HNO3?
1) 10
2) 1.0
3) 0
4) -1.0
5) none of these
13. Nitrous acid, HNO2, has an ionization constant Ka = 4.0 x 10-4. The pH of a 0.25 M HNO2 solution is:
1) 2.00
2) 2.30
3) 2.70
4) 3.70
5) none of these
14. In a solution prepared by dissolving 0.10 mole of an acid HX in enough water to make 1.00 L of solution,
the pH is observed to 1.35. What is the Ka for this acid?
1) 2.0 x 10-2
2) 3.6 x 10-2
3) 4.5 x 10-2
4) 5.0 x 10-12
5) None of these
15. A 0.05 M aqueous solution of a weak monoprotic acid is 1.2% ionized at equilibrium at 25 °C.
Ka for this acid is:
1) 0.034
2) 6.4 x 10-8
3) 7.3 x 10-33
4) 29
5) none of these
16. What is the pOH of a 0.10 M solution of Ba(OH)2?
1) 13.30
2) 0.70
3) 1.00
4) 13.00
5) none of these
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17. The [OH-] in a 0.50 M pyridine solution (C5H5N; Kb = 1.7 x 10-9) is:
1) 0.50 M
2) 2.9 x 10-5 M
3) 1.8 x 10-9 M
4) 3.3 x 10-10 M
5) none of these
18. The equilibrium constant for the reaction
NH4+ + OH- ↔ NH3 + H2O
is:
1) 1/Kb for NH3
2) 1/Ka for NH4+
3) Kw/Ka for NH4+
4) Kw/Kb for NH3
5) Kb for NH3/Kw
19. What is the pH of a 0.05 M solution of ascorbic acid, Vitamin C (Ka1 = 7.9 x 10-5; Ka2=1.6 x 10-12)
1) 1.3
2) 2.7
3) 3.1
4) 5.4
5) 6.5
20. Given:
HAc
Ka = 1.8 x 10-5
H2CO3 Ka1= 4.3 x 10-7
Ka2 = 5.6 x 10-11
Which of the following 0.01M solutions will have the highest pH?
1) HAc
2) NaAc
3) Na2CO3
4) H2CO3
5) NaHCO3
21. If Ka for HCN is 6.2 x 10-10, what is Kb for CN-?
1) 6.2 x 10-24
2) 6.2 x 104
3) 1.6 x 10-5
4) 1.6 x 10-23
5) none of these
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22. Which of the following substances can be dissolved in water to give a basic solution?
1) NH4Cl
2) NaBr
3) KF
4) NaHSO4
5) KNO3
23. What is the pH of a 1.0 M aqueous solution of NaCl?
1) 7.0
2) greater than 7.0
3) less than 7.0
4) not enough information
5) too tired to answer
24. What is the pH of a 1.0 M aqueous solution of KNO2?
1) 7.0
2) greater than 7.0
3) less than 7.0
4) not enough information
25. Which of the following is the STRONGEST Lewis acid?
1) Na+
2) Al3+
3) CH3COO4) Mg2+
5) Cl26. All of the following species can function as Bronsted-Lowry bases in solution EXCEPT:
1) H2O
2) NH3
3) S24) NH4+
5) HCO327. What is the pH of a 0.36M solution of sodium acetate? (Ka = 1.8 x 10-5 of acetic acid)
1) 9.15
2) 4.85
3) 2.59
4) 11.41
5) 7.00
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28. Which of the following will NOT give an acid solution when dissolved in water?
1) K2O
2) P2O5
3) CO2
4) NO2
5) SO3
29. HCN is a weak acid (Ka = 6.2 x 10-10) NH3 is a weak base (Kb = 1.8 x 10-5). A 1.0 M solution of NH4CN
would be
1) strongly acidic
2) weakly acidic
3) neutral
4) weakly basic
30. The equilibrium constant for this reaction is approximately 0.001.
HPO42-(aq) + HCO3-(aq)  H2PO4-(aq) + CO32-(aq)
Which is the strongest conjugate base in this reaction?
1) HPO42-(aq)
2) HCO3-(aq)
3) H2PO4-(aq)
4) CO32-(aq)
5) there is no base in this reaction
31. Calculate the pH of a 0.00175 M solution of KOH.
1)
2)
3)
4)
5)
7.89
11.2
12.7
-2.76
2.76
32. Calculate the [H+] in a solution that has a pH of 8.38.
1)
2)
3)
4)
5)
4.17 x 10-9
2.40 x 108
3.8 x 10-8
1.21 x 10-2
1.21 x 102
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33. If an acid, HA, is 15% dissociated in a 2.00 M solution, what is Ka for the acid?
1)
2)
3)
4)
6.4 x 10-3
2.2 x 10-2
5.3 x 10-2
7.5 x 10-2
34. What is the pH of a 0.00350 M HNO3 solution?
1)
2)
3)
4)
5)
2.456
1.018
6.780
4.903
-2.466
35. Calculate the [H3O+] of a 0.10 M solution of NH4Cl in H2O at 25°C (Kb for NH3 = 1.8 x 10-5)
1)
2)
3)
4)
5)
5.6 x 10-10
2.4 x 10-5
1.8 x 10-6
1.8 x 10-5
7.5 x 10-6
36. What concentration of HOCl (Ka = 3.5 x 10-8) has the same pH as that of 2.50 x 10-4 M HNO3?
1)
2)
3)
4)
5)
6.8 10-8 M
3.5 x 10-2 M
1.79 M
0.560 M
3.93 M
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37. Based upon the following values of Ka, place the acids in order from weakest to strongest:




HCN
(Ka = 6.2 x 10-10)
HCOOH (Ka = 1.78 x 10-4)
HC2H3O2 (Ka = 1.8 x 10-5)
HNO2
(Ka = 4.6 x 10-4)
1) HCN < HC2H3O2 < HCOOH < HNO2
2) HCN < HNO2 < HC2H3O2 < HCOOH
3) HNO2 < HCOOH < HC2H3O2 < HCN
4) HC2H3O2 < HCN < HNO2 < HCOOH
5) HCOOH < HNO2 < HCN < HC2H3O2
38. Which of the following is not true for the dissociation of a strong acid?
1)
2)
3)
4)
5)
The conjugate base will be weak
Ka is large
The equilibrium lies far to the left
The equilibrium lies far to the right
[H+] >> [HA]
39. What are the conjugate bases in the following reaction?
1)
2)
3)
4)
5)
H2SO4 + H2O → HSO4- + H3O+
HSO4- and H3O+
H2SO4, H2O and HSO4H2O and HSO4H2SO4 and H2O
H2SO4 and H3O+
40. The pH of a 0.150 M solution of an aqueous weak monoprotic acid is 4.10. Calculate Ka for the acid.
1)
2)
3)
4)
5)
4.21 x 10-8
5.09 x 10-2
2.26 x 10-4
7.94 x 10-5
6.31 x 10-9
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41. At 25°C a solution has a [OH-] = 2.90 x 10-2. Calculate the pH of the solution.
1)
2)
3)
4)
5)
1.54
3.17
12.5
-4.54
9.03
42. The pH of a 0.500 M solution of KC2H3O2 is:
1) greater than 7
2) less than 7
3) 7
43. Which of the following is a conjugate acid/base pair?
1)
2)
3)
4)
5)
1. (4)
2. (2)
3. (3)
4. (4)
5. (3)
6. (1)
7. (1)
8. (3)
9. (3)
10. (3)
11. (3)
12. (4)
13. (1)
14. (2)
15. (5)
16. (2)
17. (2)
18. (1)
19. (2)
20. (3)
21. (3)
22. (3)
HCl/OClH2SO4/SO42NH4+/NH3
H3O+/OHnone of these
23. (1)
24. (2)
25. (2)
26. (4)
27. (1)
28. (1)
29. (4)
30. (4)
31. (2)
32. (1)
33. (3)
34. (1)
35. (5)
36. (3)
37. (1)
38. (3)
39. (3)
40. (1)
41. (5)
42. (1)
43. (3)
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FROM THE 2014 AP CHEMISTRY EXAM:
CH3CH2COOH(aq) + H2O(l)  CH3CH2COO- + H3O+
Propanoic acid, CH3CH2COOH, is a carboxylic acid that reacts with water according to the equation above. At
25 °C the pH OF a 50.0 mL sample of 0.20 M CH3CH2COOH is 2.79.
a) Identify a Bronsted-Lowry conjugate acid-base pair in the reaction. Clearly label which is the acid
and which is the base.
b) Determine the value of Ka for propanoic acid at 25°C
c) For each of the following statements, determine whether the statement is true or false. In each case,
explain the reasoning that supports your answer.
i) The pH of a solution prepared by mixing the 50.0 mL sample of 0.20 M CH3CH2COOH with
a 50.0 mL sample of 0.20 M NaOH is 7.00
ii) If the pH of a hydrochloric acid solution is the same as the pH of a propanoic acid solution,
then the molar concentration of the hydrochloric acid solution must be less than the molar
concentration of the propanoic acid solution.
A student is given the task of determining the concentration of a propanoic acid solution of unknown
concentration. A 0.0173 M NaOH solution is available to use as the titrant. The student uses a 25.00 mL
volumetric pipet to deliver the propanoic acid solution to a clean, dry flask. After adding an
appropriate indicator to the flask, the student titrates the solution with the 0.173 M NaOH, reaching the
end point after 20.52 mL of the base solution has been added.
d) Calculate the molarity of the propanoic acid solution.
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Various Resources:
http://www.sciencegeek.net/APchemistry/APtaters/chap14rev.htm
https://www.asdk12.org/
AP College Board
http://www.smithstudents.com/AP_Resources_files/SG16abEquil.pdf
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