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Equilibrium Multiple Choice Review Questions for AP Chemistry

based on 6 ratings
By — McGraw-Hill Professional
Updated on Feb 9, 2011

Review the following concepts if necessary:

Problems

Answer the following questions in 35 minutes. You may not use a calculator. You may use the periodic table at the back of the book.

  1. A 0.1-molar solution of acetic acid (CH3COOH) has a pH of about
    1. 1
    2. 3
    3. 7
    4. 10
    5. 14
  2. Using the above information, choose the best answer for preparing a pH = 8 buffer.

    1. K2HPO4 + KH2PO4
    2. H3PO4
    3. K2HPO4 + K3PO4
    4. K3PO4
    5. K2HPO4 + H3PO4
  3. Ka, the acid dissociation constant, for an acid is 9 × 10–4 at room temperature. At this temperature, what is the approximate percent dissociation of the acid in a 1.0 M solution?
    1. 0.03%
    2. 0.09%
    3. 3%
    4. 5%
    5. 9%
  4. Use the following information for questions 4–6.

    1. a solution with pH = 7.
    2. a solution with a pH < 7, which is not a buffer
    3. a solution with a pH < 7, which is a buffer
    4. a solution with a pH > 7, which is not a buffer
    5. a solution with a pH > 7, which is a buffer

    Ionization Constants:

  5. A solution with an initial KCOOH concentration of 1 M, and an initial K2HPO2 concentration of 1 M.
  6. A solution with an initial H3PO2 concentration of 1 M, and an initial KH2PO2 concentration of 1 M.
  7. A solution with an initial CH3NH2 concentration of 1 M, and an initial CH3NH3Cl concentration of 1 M.
  8. A solution of a weak base is titrated with a solution of a standard strong acid. The progress of the titration is followed with a pH meter. Which of the following observations would occur?
    1. The pH of the solution gradually decreases throughout the experiment.
    2. Initially the pH of the solution drops slowly, and then it drops much more rapidly.
    3. At the equivalence point the pH is 7.
    4. After the equivalence point, the pH becomes constant because this is the buffer region.
    5. The pOH at the equivalence point equals the pKb of the base.
  9. What is the ionization constant, Ka, for a weak monoprotic acid if a 0.30-molar solution has a pH of 4.0?
    1. 9.7 × 10–10
    2. 4.7 × 10–2
    3. 1.7 × 10–6
    4. 3.0 × 10–4
    5. 3.3 × 10–8
  10. Phenol, C6H5OH, has Ka = 1.0 × 10–10. What is the pH of a 0.010 M solution of phenol?
    1. between 3 and 7
    2. 10
    3. 2
    4. between 7 and 10
    5. 7
  11. You are given equimolar solutions of each of the following. Which has the lowest pH?
    1. NH4Cl
    2. NaCl
    3. K3PO4
    4. Na2CO3
    5. KNO3
  12. When sodium nitrite is dissolved in water
    1. the solution is acidic because of hydrolysis of the sodium ion
    2. the solution is neutral
    3. the solution is basic because of hydrolysis of the sodium ion
    4. the solution is acidic because of hydrolysis of the NO2 ion
    5. the solution is basic because of hydrolysis of the NO2 ion
  13. Questions 12–15 refer to the following aqueous solutions. All concentrations are 1 M.

    1. HNO2C2O4 (oxalic acid) and KHC2O4 (potassium hydrogen oxalate)
    2. KNO3 (potassium nitrate) and HNO3 (nitric acid)
    3. NH3 (ammonia) and NH4NO3 (ammonium nitrate)
    4. C2H5NH2 (ethylamine) and KOH (potassium hydroxide)
    5. CH3NH2 (methylamine) and HC2H3O2 (acetic acid)
  14. The most acidic solution (lowest pH)
  15. The solution with a pH nearest 7
  16. A buffer with a pH > 7
  17. A buffer with a pH < 7
  18. Determine the OH(aq) concentration in 1.0 M aniline (C6H5NH2) solution. (Kb for aniline is 4.0 × 10–10.)
    1. 2.0 × 10–5 M
    2. 4.0 × 10–10 M
    3. 3.0 × 10–6 M
    4. 5.0 × 10–7 M
    5. 1.0 × 100 M
  19. A student wishes to reduce the zinc ion concentration in a saturated zinc iodate solution to 1 × 10–6 M. How many moles of solid KIO3 must be added to 1.00 liter of solution? (Ksp Zn(IO3)2 = 4 × 10–6 at 25°C)
    1. 1 mol
    2. 0.5 mol
    3. 0.0001 mol
    4. 4 mol
    5. 2 mol
  20. At constant temperature, a change in volume will NOT affect the moles of substances present in which of the following?
  21. The equilibrium constant for the hydrolysis of C2O42– is best represented by which of the following?
  22. The above equation has an equilibrium constant that is less than 1. What are the relative strengths of the acids and bases?

  23. What is the equilibrium constant for the above reaction? The successive acid dissociation constants for H2S are 9.5 × 10–8 (Ka1) and 1 × 10–19 (Ka2). Ksp, the solubility product constant, for ZnS equals 1.6 × 10–24.

    1. 1.6 × 10–24/9.5 × 10–8
    2. 1 × 10–79/1.6 × 10–24
    3. 9.5 × 10–27/1.6 × 10–24
    4. 9.5 × 10–8/1.6 × 10–24
    5. 1.6 × 10–24/9.5 × 10–27
  24. Which species, in the above equilibrium, behave as bases?

    1. HPO42–
    2. H2PO4
    3. H2O
    1. I only
    2. I and II
    3. II and III
    4. I and III
    5. III only
  25. As shown above, malonic acid is a diprotic acid. The successive equilibrium constants are 1.5 × 10–3 (Ka1) and 2.0 × 10–6 (Ka2). What is the equilibrium constant for the above reaction?

    1. 1.0 × 10–14
    2. 2.0 × 10–6
    3. 4.0 × 10–12
    4. 3.0 × 10–9
    5. 1.5 × 10–3
  26. An equilibrium mixture of the reactants is placed in a sealed container at 150°C. The amount of the products may be increased by which of the following changes?

    1. raising the temperature of the container
    2. increasing the volume of the container
    3. adding 1 mol of C(s) to the container
    1. II only
    2. I and II
    3. I only
    4. II and III
    5. III only
  27. An equal number of moles of each of the reactants are sealed in a container and allowed to come to the equilibrium shown above. At equilibrium which of the following must be true?

    1. [CO2] must equal [H2O]
    2. [O2] must be less than [C2H4]
    3. [CO2] must be greater than [C2H4]
    1. II and III
    2. I only
    3. III only
    4. II only
    5. I and II
  28. A 1.00-L flask is filled with 0.30 mol of CH4 and 0.40 mol of CO2, and allowed to come to equilibrium. At equilibrium, there are 0.20 mol of CO in the flask. What is the value of Kc, the equilibrium constant, for the reaction?

    1. 1.2
    2. 0.027
    3. 0.30
    4. 0.060
    5. 3.0
  29. The above materials were sealed in a flask and allowed to come to equilibrium at a certain temperature. A small quantity of O2(g) was added to the flask, and the mixture allowed to return to equilibrium at the same temperature. Which of the following has increased over its original equilibrium value?

    1. the quantity of NO2(g) present
    2. the quantity of NO(g) present
    3. the equilibrium constant, K
    4. the rate of the reaction
    5. the partial pressure of NO(g)
  30. In order to increase the value of the equilibrium constant, K, which of the following changes must be made to the above equilibrium?

    1. increase the temperature
    2. increase the volume
    3. decrease the temperature
    4. add CO(g)
    5. add a catalyst
  31. The equilibrium constant, K, for the above equilibrium is 7.2 × 10–2. This value implies which of the following?

    1. A solution with equimolar amounts of HC3H5O2(aq) and HCOO(aq) is neutral.
    2. C3H5O2(aq) is a stronger base than HCOO(aq).
    3. HC3H5O2(aq) is a stronger acid than HCOOH(aq).
    4. HCOO(aq) is a stronger base than C3H5O2(aq).
    5. The value of the equilibrium does not depend on the temperature.
  32. The addition of nitric acid increases the solubility of which of the following compounds?
    1. KCl(s)
    2. Pb(CN)2(s)
    3. Cu(NO3)2(s)
    4. NH4NO3(s)
    5. FeSO4(s)
  33. The Ksp for Mn(OH)2 is 1.6 × 10–13. What is the molar solubility of this compound in water?
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