AP Chemistry Chapter 14 Review Packet Multiple Choice Questions: 2. What is the equilibrium constant for the following reaction?

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1 AP Chemistry Chapter 14 Review Packet Multiple Choice Questions: Name 1. For the stepwise dissociation of aqueous H 3 PO 4, which of the following is NOT a conjugate acid-base pair? a. HPO 4 and PO 4 3 b. H 3 PO 4 and H 2 PO 4 1 c. H 2 PO 4 1 and HPO 4 d. H 2 PO 4 1 and PO 4 3 e. H 3 O +1 and H 2 O 2. What is the equilibrium constant for the following reaction? N H 3 O +1 HN 3 + H 2 O The K a value for HN 3 = 1.9 x 10 5 a. 5.3 x b. 1.9 x 10 9 c. 1.9 x 10 5 d. 5.3 x 10 4 e. 1.9 x The hydrogen sulfate (or bisulfate) ion HSO 4 1 can act as either an acid or a base in water solution. In which of the following equations does HSO 4 1 act as an acid? a. HSO H 2 O H 2 SO 4 + OH 1 b. HSO H 3 O +1 SO H 2 O c. HSO OH 1 H 2 SO 4 + O d. HSO H 2 O SO 4 + H 3 O Using the following K a values, indicate the correct order of base strength. HNO 2 K a = 4.0 x 10 4 HF K a = 7.2 x 10 4 HCN K a = 6.2 x a. CN 1 > NO 1 2 > F 1 > H 2 O > Cl 1 b. Cl 1 > H 2 O > F 1 1 > NO 2 > CN 1 c. CN 1 > F 1 > NO 1 2 > Cl 1 > H 2 O d. H 2 O > CN 1 > NO 1 2 > F 1 > Cl 1

2 5. Which of the following is the equilibrium constant expression for the dissociation of the weak acid HOCl? a. K = [H +1 ] [OCl 1 ] [HOCl] b. K = [H +1 ] [OCl 1 ] c. K = [HOCl] [H +1 ] [OCl 1 ] d. K = [H +1 ] [O ] Cl 1 ] [HOCl] Use the following equations for questions 6 and 7. The following three equations represent equilibria that lie far to the right. HNO 3 (aq) + CN 1 (aq) HCN (aq) + NO 3 1 (aq) HCN (aq) + OH 1 (aq) H 2 O (l) + CN 1 (aq) H 2 O (l) + CH 3 O 1 (aq) CH 3 OH (aq) + OH 1 (aq) 6. Identify the strongest acid. a. HCN b. HNO 3 c. H 2 O d. OH 1 e. CH 3 OH 7. Identify the strongest base. a. CH 3 O 1 b. CH 3 OH c. CN 1 d. H 2 O e. NO In which of the following reactions does the H 2 PO 4 1 ion act as an acid? a. H 3 PO 4 + H 2 O H 3 O +1 + H 2 PO 4 1 b. H 2 PO H 2 O H 3 O +1 + HPO 4 c. H 2 PO OH 1 H 3 PO 4 + O d. The ion cannot act as an acid. e. Two of these

3 9. Which of the following is true for the dissociation of a weak acid? a. K a is large. b. The equilibrium lies far to the right. c. The equilibrium lies far to the left. d. [H +1 ] >>[HA] e. The conjugate base will be weak. 10. Which of the following reactions is associated with the definition of K b? a. Zn(OH) +2 6 [Zn(OH) 5 (OH)] +1 + H +1 b. CN 1 + H +1 HCN c. F 1 + H 2 O HF + OH 1 d. Cr H 2 O Cr(OH 2 ) Use the following K a s to answer the question. HAc K a = 1.8 x 10 5 H 2 CO 3 K a1 = 4.3 x 10 7 K a2 = 5.6 x a. HAc b. NaAc c. Na 2 CO 3 d. H 2 CO 3 e. NaHCO The conjugate acid and conjugate base of the bicarbonate ion, HCO 3 1, are, respectively: a. H 3 O +1 and OH 1 b. H 3 O +1 and CO 3 c. H 2 CO 3 and OH 1 d. H 2 CO 3 and CO 3 e. CO 3 and OH Which of the following species is present in the greatest concentration in a M H 2 SO 4 solution in H 2 O? a. H 3 O +1 b. HSO 4 1 c. H 2 SO 4 d. All species are in equilibrium and therefore have the same concentration. e. SO 4

4 14. The sodium salt, NaA, of a weak acid is dissolved in water; no other substance is added. Which of these statements (to a close approximation) is true? a. [H +1 ] = [A 1 ] b. [H +1 ] = [OH 1 ] c. [A 1 ] = [OH 1 ] d. [HA] = [OH 1 ] 15. The hydrogen halides (HF, HCl, HBr, and HI) are all polar molecules. The strength of the acid each forms in water is based on which of the following? a. the polarity of the molecule b. the size of the molecule c. the strength of the bond d. two of these 16. Which factor listed below is most important in determining the strength of an oxyacid? a. the size of the molecule b. the ability of the molecule to change atomic orientation c. the identity of the central atom in the molecule d. the number of oxygen atoms present in the molecule For questions 17-19, use the following information. If the following substance is dissolved in pure water, will the solution be acidic, neutral, or basic? a. Acidic b. Neutral c. Basic 17. solid sodium nitrate 18. solid silver chloride 19. solid sodium carbonate 20. As water is heated, its ph decreases. This means that a. the water is no longer neutral. b. the K w value is decreasing. c. the water has a lower [OH 1 ] than cooler water. d. the dissociation of water is an endothermic process.

5 Free-Response Questions 1. Calculate the ph of 5.00 ml of 1.5 M hydrochloric acid diluted to 100. ml. 2. Indicate whether the following solution is acidic, basic, or neutral: [H +1 ] = 1.5 x M. 3. Identify the acid, base, conjugate acid, and conjugate base in the following reaction: NH 2 1 (aq) + H 2 O (l) NH 3 (aq) + OH 1 (aq) 4. Citric acid, H 3 C 6 H 5 O 7, is present in citrus fruits. Calculate the ph of a M solution of citric acid. Explain any approximations or assumptions that you make in your calculations. K a1 = 3.5 x 10 4, K a2 = 1.7 x 10 5, and K a3 = 4.0 x Identify the Lewis acid and Lewis base in the following reaction: Fe(ClO 4 ) 3 (s) + 6 H 2 O (l) Fe(H 2 O) 6 +3 (aq) + 3 ClO 4 1 (aq) 6. At normal body temperature, 37 C, K w = 2.4 x Calculate [H +1 ], [OH 1 ], ph and poh for a neutral aqueous solution at this temperature. 7. Determine the nature of magnesium sulfite when dissolved in water. (Is it acidic, basic, or neutral). Explain. 8. Calculate the percent ionization of hydroazoic acid, HN 3, in solutions of the following concentrations: M and M. K a = 1.9 x Calculate the ph of a M solution of ethylamine, C 2 H 5 NH 2. K b = 6.4 x Write the balanced net ionic equation and the base-dissociation-constant expression for the reaction of the formate ion, CHO 2 1 (a weak base) with water. 11. Codeine, C 18 H 21 NO 3, is a weak organic base. A 5.0 x 10 3 M solution of codeine has a ph of Calculate the value of K b for this substance. 12. How many grams of potassium hydroxide are necessary to prepare 800. ml of a solution of ph = 11.56? Use the following information for questions Acrylic acid (CH 2 CHCO 2 H) is a precursor for many important plastics. K a for acrylic acid is 5.6 x Calculate the ph of a 0.10 M solution of acrylic acid. 14. Calculate the percent dissociation of a 0.10 M solution of acrylic acid. 15. Calculate the ph of a M solution of sodium acrylate (NaC 3 H 3 O 2.)

6 16. Tartaric acid is found in many plants (grapes, for example). It is partly responsible for the dry texture of certain wines. Calculate the ph of a M solution of tartaric acid. (K a1 = 1.0 x 10 3 and K a2 = 4.6 x 10 5.) Explain any approximations that you may make. 17. Find the ph of a 0.15 M solution of methylamine, NH 2 CH 3. (K b = 4.4 x 10 4 ) 18. Calculate the ph and poh of a M solution of oxalic acid. (K a1 = 6.5 x 10 and K a2 = 6.1 x 10 5.) Explain any approximations that you may make. 19. Hemoglobin (abbreviated Hb) is a protein that is responsible for the transport of oxygen in the blood of mammals. Each hemoglobin molecule contains four iron atoms that are the binding sites for O 2 molecules. The oxygen binding is ph dependent. The relevant equilibrium reaction is +4 HbH O 2 Hb(O 2 ) H +1 Use LeChâtelier s principle to answer the following: a. What form of hemoglobin, HbH 4 +4 or Hb(O 2 ) 4 is favored in the lungs? What form is favored in the cells? b. When a person hyperventilates, the concentration of CO 2 in the blood is decreased. CO 2 is a weak acid in the reaction: CO 2 + H 2 O HCO H +1 How does this affect the oxygen-binding equilibrium? How does breathing into a paper bag help to counteract this effect? c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate (NaHCO 3 ) solution is given. Why is this necessary?