CHEM 1200
Practice Test 3

Note: These questions are representative of the types of questions you can expect on the test. The actual test will be longer, typically between 20-40 questions. You will need to bring a SCANTRON answer sheet to each test.


1. Identify the conjugate base of HSO₄^- in the following reaction

H₂PO₄^-    +    HSO₄^-   =   H₃PO₄    +    SO₄^2-

a. H₂PO₄^-
b. H₂SO₄
c. H₂O
d. H₃PO₄
e. SO₄<sup>2-


2. The OH-concentration in a solution of 7.5 x10-3 M Ca(OH)₂ is

a. 7.50 x 10-3 M
b. 1.50 x 10-2 M
c. 1.30 x 10-12 M
d. 1.00 x 10-7 M
e. 1.00 x 10-14 M



3. Calculate the H+ ion concentration in 8.8 x10-4 M Ca(OH)₂

a. 8.8 x 10-4 M
b. 1.8 x 10-3 M
c. 2.2 x 10-11 M
d. 1.1 x 10-11 M
e. 5.7 x 10-12 M



4. A 0.14 M HNO₂ solution is 5.7% ionized. Calculate the H+ ion concentration

a. 8.0 x 10-3 M
b. 0.057 M
c. 0.13 M
d. 0.14 M
e. 0.80 M



5. Calculate the pH of 3.5 x 10-3 M HNO₃

a. - 2.46
b. 0.54
c. 2.46
d. 3.00
e. 3.46


6. Which of the following is an acid, but not a Bronsted acid?

a. HCN
b. CO₃2-
c. OH-
d. Cl-
e. Al3+


7. The K_sp of Bi₂S₃ is 1.6 x 10-72. What is the molar solubility of this compound in aqueous solution?

a. 1.6 x 10-72 M
b. 4.4 x 10-15 M
c. 1.7 x 10-15 M
d. 1.2 x 10-24 M



8. The pH of a 0.25 M weak monoprotic acid (HA) solution is 3.50. What is the K_a value for this acid?

a. 7.1 x 10-4
b. 1.0 x 10-7
c. 1.3 x 10-3
d. 4.0 x 10-7
e. 1.0 x 107



9. Which one of the following salts will form a basic solution on dissolving in water?

a. NaCl
b. KCN
c. NaNO₃
d. NH₄NO₃
e. FeCl₃


10. Calculate the pH of a buffer solution which contains 0.25 M benzoic acid (C₆H₅CO₂H) and 0.15 M sodium benzoate (NaC₆H₅CO₂). Given K_a = 6.5 x 10-5.

a. 3.97
b. 4.83
c. 4.19
d. 3.40
e. 4.41


11. For which type of titration will the pH be basic at the equivalence point?

a. strong acid vs. strong base
b. strong acid vs. weak base
c. weak acid vs. strong base
d. all of the above
e. none of the above


12. The molar solubility of MgCO₃ is 1.8 x 10-4 mol/L. What is K_sp for this compound?

a. 1.8 x 10-4
b. 3.6 x 10-4
c. 1.3 x 10-7
d. 3.2 x 10-8
e. 2.8 x 10-14



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