AP Chem Ch 15 Practice Quiz
1. The common ion effect
a) reduces the dissociation of a weak acid
b) increases the dissociation of a weak acid
c) changes the equilibrium constant for a reaction
d) Has no effect on the dissociation of a weak acid
2. Which of the following combinations in solution CANNOT be a buffer?
a) HNO2/KNO2
b) KCl/HCl
c) NH3/NH4NO3
d) NaH2PO4/H3PO4
e) NaF/HF
3. Which of the following combinations in solution CAN produce a buffer?
a) KHSO4/H2SO4
b) Na2CO3/NaOH
c) HCl/NaF
d) HCl/NH4Cl
e) NaOH/NaCN
4. What change will be caused by addition of a small amount of a strong acid to a solution containing
fluoride ion and hydrogen fluoride?
a) The concentration of hydronium ion will significantly increase
b) The concentration of fluoride ion will increase as will the concentration of hydronium ion
c) The concentration of hydrogen fluoride will be decreased and the concentration of fluoride ion will be
increased
d) The concentration of fluoride ion will be decreased and the concentration of hydrogen fluoride will be
increased
e) The fluoride ion will precipitate out of the solution as its acid salt
5. What is the pH of a solution prepared by mixing 50 ml of a 0.10M solution of HF with 25 ml of a 0.20M
solution of NaF? (The pKa of HF is 3.14)
a) 3.14
b) 10.80
c) 5.83
d) 7.35
e) 12.00
6. What is the pH of a solution that is 0.2M in acetic acid (Ka = 1.8 x 10 -5) and 0.2M in sodium acetate?
a) 4.7
b) 9.3
c) 7.0
d) 5.4
e) 8.6
7. For ammonia, Kb is 1.8 x 10-5. to make a buffered solution of pH 10.0, the ratio of NH4Cl to NH3 must
be:
a) 1.8 : 1
b) 1 : 1.8
c) 0.18 : 1
d) 1 : 0.18
e) none of these
8. A solution contains 0.500M HA (Ka = 1.0 x 10 -8) and 0.250M NaA. What is the [H+] after 0.10 mole of
HCl(g) is added to 1.00 L of this solution?
a) 1.4 x 10-8M
b) 2.0 x 10-8M
c) 2.5 x 10-9M
d) 4.0 x 10-8M
e) none of these
9. Given 100.0 ml of a buffer that is 0.50 M in HOCl and 0.40 M in NaOCl, what is the pH after 10.0 ml of
1.0 M NaOH has been added?
(Ka for HOCl =3.5 x 10-8)
a) 6.45
b) 6.64
c) 7.36
d) 7.45
e) 7.55
10. What is the molarity of a sodium hydroxide solution if 25.0 ml of this solution reacts exactly with 22.30
ml of 0.253 M sulfuric acid?
a) 0.113M
b) 0.226M
c) 0.284M
d) 0.451M
e) 0.567M
11. If 25 ml of 0.75M HCl are added to 100 ml of 0.25M NaOH, what is the final pH?
a) 12.70
b) 12.80
c) 1.30
d) 1.20
e) 7.00
12. Consider the titration of 100.0 ml of 0.500M NH 3 (Kb = 1.8 x 10-5) with 0.500 M HCl.
After 50.0 ml of HCl have been added, the [H+] of the solution is:
a) 1.8 x 10-5 M
b) 5.6 x 10-10 M
c) 1.2 x 10-5 M
d) 1.0 x 10-7 M
e) none of these
13. 50.0 ml of 0.10 M HNO2 (Ka = 4.0 x 10-4) are being titrated with 0.10 M NaOH. The pH after 25.0 ml
of NaOH have been added is
a) 7.00
b) 1.00
c) 12.50
d) 3.40
e) none of these
14. 75.0 ml of 0.05 M HCN (Ka = 6.2 x 10-10) is being titrated with 0.500 M NaOH. What volume of 0.500
M NaOH is required to reach the stoichiometric point (equivalence point)?
a) 75.0 ml
b) 7.50 ml
c) 750. ml
d) cannot determine without knowing the pH at the equivalence point
e) none of these
15. 0.0100 mole of a weak acid (HA) was dissolved in a 100.0 ml of distilled water and a titration was
performed using 0.100M NaOH. After 40.00 ml of 0.100 M NaOH were added, the pH of the solution was
observed to be 4.00. The Ka value for HA is:
a) 1.0 x 10-4
b) 6.7 x 10-5
c) 1.5 x 10-4
d) 1.0 x 10-10
e) none of these
16. You dissolve 1.00 g of an unknown diprotic acid in 200.0 ml of H 2O. This solution is just neutralized
by 5.00 ml of a 1.00M NaOH solution. What is the molar mass of the unknown acid?
a) 25.0
b) 50.0
c) 200.
d) 400.
e) none of these
17. Consider an experiment where 35.0 ml of 0.175 M acetic acetic acid, HC 2H3O3, is titrated with
0.25 M NaOH. What is the pH at the equivalence point of this titration? The Ka for acetic acid is 1.8 x
10-5.
a) 5.12
b) 2.87
c) 11.13
d) 8.88
18. For the pH curve shown, which of the following is true?
a) A weak acid is being titrated with strong base
b) A strong acid is being titrated with strong base
c) A weak base is being titrated with strong acid
d) A strong base is being titrated with strong acid
19. Assuming 100 ml of HCl is being titrated, use the plot to determine the initial concentration of the HCl.
a) 1M
b) 0.1M
c) 0.01M
d) 1 x 10-7M
e) 3.1 x 10-3M
20. What is the pH at the equivalence point in the following pH curve?
a) 2.2
b) 3.9
c) 7.0
d) 8.2
e) 12.0
21. What is the approximate Ka of the acid used in this titration?
a) 0.005
b) 1.3 x 10-4
c) 1.0 x 10-7
d) 6.3 x 10-9
22. Which of the following is the net ionic equation for the reaction that occurs during the titration of
nitrous acid (HNO2) with potassium hydroxide?
a) HNO2 + K+ + OH- ---> KNO2 + H2O
b) HNO2 + H2O ----> NO2- + H3O+
c) HNO2 + KOH ----> K+ + NO2- + H2O
d) HNO2 + OH- ----> NO2- + H2O
e) H+ + OH- ----> H2O
23. A 100. ml sample of 0.10 M HCl is mixed with 50. ml of 0.10 M NH 3. What is the resulting pH?
a) 12.52
b) 3.87
c) 1.30
d) 7.85
e) 1.48
24. Calculate the pH at the equivalence point for the titration of 1.0M ethylamine, C 2H5NH2, by 1.0M
HClO4. (pKb for C2H5NH2 = 3.25).
a) 6.05
b) 2.24
c) 5.53
d) 2.09
e) 5.38
25. In the titration of a weak acid HA with 0.100 M NaOH, the equivalence point is known to occur at a pH
value of approximately 10. Which of the following indicator acids would be best to use to mark the
endpoint of the titration?
a) Indicator A, Ka = 10-14
b) Indicator B, Ka = 10-11
c) Indicator C, Ka = 10-8
d) Indicator A, Ka = 10-6
e) None of these will work well.
26. Given the following Ksp values:
BaSO4 1.5 x 10-9
CoS
5.0 x 10-22
PbSO4 1.3 x 10-8
AgBr
5.0 x 10-13
Which of the following compounds is the most soluble?
a) BaSO4
b) CoS
c) PbSO4
d) AgBr
e) All have equal solubility
27. Which of the following compounds has the LOWEST solubility in water?
a) Al(OH)3 Ksp = 2 x 10-32
b) CdS
Ksp = 1.0 x 10 -28
c) PbSO4
Ksp = 1.3 x 10-8
d) Sn(OH)2 Ksp = 3 x 10-27
e) MgC2O4 Ksp = 8.6 x 10-5
(C2O4-2 is the anion)
28. The solubility of CaSO4 in pure water at 0 degrees celsius is 1 gram per liter; the molar mass is 136.
The value of the solubility product, Ksp, is
a) 1 x 10-3
b) 7 x 10-2
c) 1 x 10-4
d) 5 x 10-5
29. The molar solubility of BaF2 is 7.5 x 10-3 mol/L. What is the value of Ksp for BaF2?
a) 4.2 x 10-7
b) 1.7 x 10-6
c) 8.4 x 10-7
d) 8.7 x 10-2
e) 7.5 x 10-3
30. The Ksp of Ag2CO3 is 8.1 x 10-12. What is the molar solubility (mole/L) of silver carbonate?
a) 1.3 x 10-4
b) 2.9 x 10-6
c) 2.0 x 10-4
d) 2.0 x 10-6
e) 8.2 x 10-12
31. What is the concentration of Al3+ in a saturated aqueous solution of Al(OH)3 (Ksp = 2.0 x 10-32)?
a) 3 x 10-9
b) 7 x 10-9
c) 2 x 10-11
d) 3 x 10-17
e) none of these
32. The molar solubility of AgCl (Ksp = 1.6 x 10 -10) in 0.0020 M sodium chloride is:
a) 0.0020
b) 1.3 x 10-5
c) 8.0 x 10-8
d) 1.7 x 10-10
e) none of these
33. How many moles of CaF2 will dissolve in 3.0 liters of 0.050 M NaF solution?
(Ksp for CaF2 = 4.0 x 10-11)
a) 8.9 x 10-9
b) 8.0 x 10-8
c) 4.8 x 10-8
d) 2.7 x 10-8
e) none of these
34. The Ksp for BaF2 is 2.4 x 10-5. When 10 ml of 0.01 M NaF is mixed with 10 ml of 0.01M BaNO 3, will
a precipitate form?
a) No, because Q is 1 x 10-12 and since it is less than Ksp, no precipitate will form.
b) Yes, because Q is 1 x 10-12 and since it is less than Ksp, a precipitate will form.
c) No, because Q is 1.25 x 10-7 and since it is less than Ksp, no precipitate will form.
d) Yes, because Q is 1.25 x 10-7 and since it is less than Ksp, a precipitate will form.
e) none of the above.
35. For which salt should the aqueous solubility be most sensitive to pH?
a) Ca(NO3)2
b) CaF2
c) CaCl2
d) CaBr2
e) CaBr2
f) CaI2
36. 0.012 moles of Na2SO4 are added to 400 ml of each of two solutions. One solution contains
1.5 x 10-3M BaCl2; the other contains 1.5 x 10-3M CaCl2. Given that Ksp for BaSO4 = 1.5 x 10-9 and Ksp
for CaSO4 = 6.1 x 10-5:
Which of the following is true?
a) BaSO4 would precipitate but CaSO4 would not
b) CaSO4 would precipitate butBaSO4 would not
c) Both BaSO4 and CaSO4 would precipitate
d) Neither BaSO4 nor CaSO4 would precipitate
e) Not enough information is given to determine if precipitation would occur.
37. Which of the following solid salts should be more soluble in 1.0M NH 3 than in water?
a) Na2CO3
b) KCl
c) AgBr
d) KNO3
e) none of these
38. Sodium chloride is added slowly to a solution that is 0.010M in Cu +, Ag+, and Au+. The Ksp values for
the chloride salts are 1.9 x 10-7, 1.6 x 10-10 and 2.0 x 10-13 respectively. Which compound will precipitate
first?
a) CuCl(s)
b) AgCl(s)
c) AuCl(s)
39. When concentrated ammonia is added to a solution of copper II ions a complex is formed. What is the
coordination number of the complex?
a) 1
b) 2
c) 4
d) 6
e) 8
----------Key---------1. (a)
2. (b)
3. (c)
4. (d)
5. (a)
6. (a)
7. (c)
8. (d)
9. (e)
10. (d)
11. (a)
12. (b)
13. (d)
14. (b)
15. (b)
16. (d)
17. (d)
18. (d)
19. (b)
20. (d)
21. (b)
22. (d)
23. (e)
24. (c)
25. (b)
26. (c)
27. (b)
28. (d)
29. (b)
30. (a)
31. (c)
32. (c)
33. (c)
34. (c)
35. (b)
36. (a)
37. (c)
38. (c)
39. (c)