12.9 Review

New Material:

1. The Ksp of Cobalt (III) Hydroxide at 25^oC is 2.5 x 10^-43.  What is the pOH of Colbalt (III) hydroxide at 25^oC?

2. A 25.0 mL sample of 0.100 M pyridine (Kb = 1.7 x 10-9) is titrated with 0.100 M hydrochloric acid. Calculate the pH after the addition of the following amounts of hydrochloric acid:
a.) 0.00 mL
b.) 8.00 mL
c.) 28.0 mL


3. The K_sp for silver sulfate is 1.2 x 10^-5. Calculate the solubility of silver sulfate in each of the following:
a.) water
b.) 0.10 M silver nitrate (common ion effect)
c.) 0.20 M potassium sulfate (common ion effect)

Review:

1. Identify the following elements:

a.) ¹⁰⁸₄₇X

b.)⁸⁵₃₆ X

2. Name/write formulas for the following compounds:

a.) NaC₂H₃O₂

b.) KH₂PO₄

c.) KMnO₄

d.) P₄O₆

e.) NaHSO₃

f.) lithium aluminum hydride

g.) copper (I) oxide

h.) potassium chlorate

i.) barium chloride

j.) dinitrogen tetroxide

3. A compound is found my mass spectral analysis to contain the following percentages of elements by mass:

C: 49.67%, Cl: 48.92%, H: 1.39%

Find the empirical formula of the compound.  Mass spectrometry shows that the compound has a molar mass of 289.9 g/mol.  What is the compound’s molecular formula?

4. How many grams of water vapor can be generated from the combustion of 18.74 g ethanol (C₂H₆O)?

5. A 25.0 mL sample of ammonia solution is analyzed by titration with hydrochloric acid.  It took 18.96 mL of 0.150 M hydrochloric acid to titrate the ammonia.  What is the concentration of the original ammonia solution?

6. Balance the following redox reactions:

a.) in acid solution: Cr₂O₇^2- + Cl^- à Cr³⁺ + Cl₂

b.) in base solution: HXeO₄^- + Pb à Xe + HPbO₂^-

7. A vacuum line in a research lab has a volume of 1.013 L.  The temperature in the lab is 23.7^oC, and the vacuum line is evacuated to a pressure of 1 x 10^-6 torr.  How many gas particles remain?

8. Given the initial partial pressures of 0.0500 atm for phosphorus pentachloride, 0.150 atm for phosphorus trichloride, and 0.250 atm for molecular chlorine, all at 250^oC, what is the equilibrium partial pressure of each component of the mixture?  What is the total pressure?  (Phosphorus pentachloride reacts to give phosphorus trichloride and molecular chlorine, where K_p = 2.15.)

9. In the combustion of methane, K = 5.67.  Predict the direction the system will shift in order to reach equilibrium.

a.) Q = 11.85

b.) Q = 3.8 x 10^-4

c.) Q = 5.67

10. Calculate the pH of a 0.237 M solution of benzoic acid, a monoprotic acic, with K_a = 6.14 x 10^-5.

11. A buffer is prepared by adding 20.5 g of acetic acid and 17.8 g sodium acetate to water to make a 500. mL solution.  Calculate the pH.