GENERAL CHEMISTRY II – CHM202
Unit 3 Practice Test
This test is intended to help you get acquainted with the types of questions you will be asked on the Unit Test administered at
the end of the unit. The answers are included at the end of the test. Do not pass in your answers to this test. This is optional
and will not be graded. Feel free to seek any help you wish on these questions. A mastery of the topics covered in them will
assure a good performance on the tests that count.
THIS IS NOT THE TAKE HOME TEST.
DO NOT PASS IN AN ANSWER SHEET FOR THIS TEST.
1. Identify the conjugate acid of CO32–.
A) H2CO3
B) HCO3–
C) H2O
D) H3O+
E) CO2
2. What is the concentration of H+ in a 2.5 M HCl solution?
A) 0
B) 1.3 M
C) 2.5 M
D) 5.0 M
E) 10. M
3. What is the H+ ion concentration in a solution with a H+ concentration of 3.5 × 10–3 M?
A) 3.5 × 10–10 M
B) 2.9 × 10–12 M
C) 1.0 × 10–3 M
D) 1.1 × 10–4 M
E) The hydrogen ion concentration cannot be determined from this information.
4. Which of the following solutions is basic?
A) [OH-] = 1.0 x 10-14 M
B) [OH-] = 1.0 x 10-7 M
C) [H3O+] = 1.0 x 10-14 M
D) [H3O+] > 1.0 x 10-7 M
E) [OH-] < 1.0 x 10-7 M
5. Calculate the pH of a carbonated beverage in which the hydrogen ion concentration is 3.4 × 10 –4 M.
A) 2.34
B) 3.47
C) 6.01
D) 7.99
E) 10.53
6. Calculate the pH of a 1.6 M KOH solution.
A) 1.60
B) –0.20
C) 0.20
D) 14.20
E) 13.80
7. Calculate the hydrogen ion concentration in a solution having a pH of 4.60.
A) 4.0 × 10–3 M
B) 4.0 × 10–9 M
C) 4.0 × 10–10 M
D) 2.5 × 10–5 M
E) 2.5 × 10–4 M
8. Which of the following solutions is acidic?
A) [H3O+] = 7.0 x 10-7 M
B) [H3O+] = 1.5 x 10-10 M
C) [H3O+] < 7.0 x 10-7 M
D) [H3O+] > 7.0 x 10-7 M
E) [H3O+] = 1.0 x 10-14 M
9. Arrange the acids HOBr, HBrO3, and HBrO2 in order of increasing acid strength.
A) HOBr < HBrO3 < HBrO2
B) HOBr < HBrO2 < HBrO3
C) HBrO2 < HOBr < HBrO3
D) HBrO3 < HOBr < HBrO2
E) HBrO3 < HBrO2 < HOBr
10. What is the pH of a 0.080 M solution of the weak base pyridine (C 5H5N; Kb = 1.7 x 10-9)?
A) 8.77
B) 5.23
C) 4.93
D) 12.90
E) 9.07
11. Select True or False: When carbon dioxide dissolves in rain water carbonic acid forms which raises the pH of rain water above 7.
A) True
B) False
12. Calculate the pH of a 0.055 M solution of CH3COONa. (Ka(CH3COOH) = 1.8 x 10-5)
A) 12.74
B) 4.74
C) 8.74
D) 9.26
E) 5.26
13. Which one of these salts will form a basic solution upon dissolving in water?
A) NaCl
B) NaNO2
C) NH4NO3
D) KBr
E) AlCl3
14. Which of the following yields a buffer solution when equal volumes of the two solutions are mixed?
A) 0.10M HCl and 0.10 M NaCl
B) 0.15 M HNO3 and 0.15 M NaNO3
C) 0.10M HF and 0.10M NaF
D) 0.10M HClO4 and 0.10 NaClO4
E) 0.15M HBr and 0.15M NaBr
15. Calculate the pH of a solution that is 0.410 M in HOCl and 0.050 M in NaOCl. [K a(HOCl) = 3.2 × 10–8]
A) 0.39
B) 3.94
C) 6.58
D) 7.49
E) 8.40
16. Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer
solution with an optimum pH of 4.6–4.8?
A) CH3COO2Na / CH3COOH (Ka = 1.8 × 10–5)
B) NH3 / NH4Cl (Ka = 5.6 × 10–10)
C) NaOCl / HOCl (Ka = 3.2 × 10–8)
D) NaNO2 / HNO2 (Ka = 4.5 × 10–4)
E) NaCl / HCl
17. Acid dissociation constants for phosphoric acid are given below.
A buffer with a pH = 7.4 can best be made by using
A) H3PO4 and NaH2PO4.
B) NaH2PO4 and Na2HPO4.
C) Na2HPO4 and Na3PO4.
D) only NaH2PO4.
E) only Na2HPO4.
18. The pH at the equivalence point of a titration may differ from 7.0 due to
A) the initial concentration of the standard solution.
B) the indicator used.
C) the self-ionization of H2O.
D) the initial pH of the unknown.
E) hydrolysis of the salt formed.
19. Calculate the pH at the equivalence point for the titration of 0.20 M HCl with 0.20 M NH 3 (Kb = 1.8 × 10–5).
A) 2.87
B) 4.98
C) 5.12
D) 7.00
E) 11.12
20. The molar solubility of manganese(II) carbonate is 4.2 × 10 –6 M. What is Ksp for this compound?
A) 4.2 × 10–6
B) 8.4 × 10–6
C) 3.0 × 10–16
D) 1.8 × 10–11
E) 2.0 × 10–3
21. Calculate the minimum concentration of Cr3+ that must be added to 0.095 M NaF in order to initiate a precipitate of
chromium(III) fluoride. (For CrF3 , Ksp = 6.6 × 10–11.)
A) 0.023 M
B) 0.032 M
C) 7.7 × 10–8 M
D) 2.9 × 10–9 M
E) 6.9 × 10–10 M
22. Select True or False: In a buffer solution where the concentration of the conjugate base is equal to the concentration of the acid,
the pH of the solution will be equal to the pKa.
A) True
B) False
ANSWERS
1. B
2. C
3. B
4. C
5. B
6. D
7. D
8. D
9. B
10. E
11. B
12. C
13. B
14. C
15. C
16. A
17. B
18. E
19. C
20. D
21. C
22. A