Acid Base Practice

Name: ___________________________________________________________ Date: ______________ Period: _______ Acids and Bases Review Session Hydrolysis: For each of the following, determine whether the solution would be acidic, basic, or neutral. 1. NaF base 6. AgNO3 acidic 2. NH4Br acid 7. MgCl2 neutral 3. LiNO3 neutral 8. CsSO4 basic 4. CaI neutral 9. CuBr2 acidic 5. KOCl basic 10. Rb2S basic Solution type: For each of the following descriptions, label the solution as a strong acid, a weak acid, a strong base, a weak base, or a buffer solution. 1. A solution of 2.5 g of NaOH dissolved in water. SB 5. A solution made by combining equimolar solutions of HCl and NaCl SA 2. A 1.0 M solution of H2SO4 SA 6. A 2.5 x 10‐3 M solution of ammonia, NH3 WB 3. A solution made with 5.0 g of NaOCl Salt/WB 7. A solution made by combining equimolar 4. A 50.0 mL solution of 1.0 M HC2H3O2 mixed with solutions of HF and NaF buffer 25.0 mL of 1.0 M KOH Buffer Multiple choice practice: 1. A student pours a 10.0mL sample of a solution containing HC2H3O2(pKa=4.8) and NaC2H3 O2 into a test tube. The student adds a few drops of bromocresol green to the test tube and observes a yellow color, which indicates that the pH of the solution is less than 3.8. Based on this result, which of the following is true about the relative concentrations of HC2H3O2 and NaC2H3O2 in the original solution? Buffer solution a. [HC2H3O2] > [NaC2H3O2] b. [HC2H3O2] = [NaC2H3O2] c. [HC2H3O2] < [NaC2H3O2] d. The relative concentrations cannot be determined without knowing the value of the pKb for C2H3O2- CH3COOH(aq)+H2O(l)⇄H3O+(aq)+CH3COO−(aq) CH3COO−(aq)+H2O(l)⇄CH3COOH(aq)+OH−(aq) 2H2O(l)⇄H3O+(aq)+OH−(aq) 2. A buffer solution is made up of acetic acid (CH3COOH) and sodium acetate (NaCH3COO). The major equilibria in the buffer system are represented above. Which of the following equilibria could be used to support the claim that the addition of a small amount of NaOH to the buffer will result in only a very small change in pH? a. CH3COOH + CH3COO‐ ⇄ CH3COO‐ + CH3COOH b. CH3COOH + OH‐ ⇄ CH3COO‐ + H2O c. H3O+ + OH‐ ⇄ 2 H2O d. CH3COOH + H2O ⇄ H3O+ + CH3COO‐ 4. A student mixes 40.mL of 0.10MHBr(aq) with 60.mL of 0.10MKOH(aq) at 25°C. What is the 3. The equilibrium reaction shown above represents the partial ionization of the weak acid HCN(aq). A 0.200MHCN(aq) solution has a pH≈4.95. If 0.05g (0.010mol) of NaCN(s) is added to 100mL of 0.200MHCN(aq), which of the following explains how and why the pH of the solution changes? a. [OH−] of the resulting solution? a. [OH-] = 0.060 M b. [OH-] = 0.033 M c. [OH-] = 0.020 M d. [OH-] = 0.00000010 M The pH will be higher than 4.95 because adding CN− will disrupt the equilibrium, resulting in H2O(l)+H2O(l)⇄H3O+(aq)+OH−(aq) 5. At 5.0°C, the value of Kw for the equilibrium shown above is 1.9×10−15 and the value of pKw is 14.73. Based on this information, an increased production of HCN that decreases the concentration of H3O+. b. The pH will be lower than 4.95 because adding CN− will disrupt the equilibrium, resulting in which of the following is correct for pure water at this temperature? an increased production of HCN that decreases a. b. c. the concentration of H3O+. c. The pH will be higher than 4.95 because CN− is a strong base that can neutralize HCN. d. d. The pH will remain close to 4.95 because the Ka is so small that hardly any products form. 1. The value of the ionization constant, Ka, for hypochlorous acid, HOCl, is 3.1x10‐8. Calculate the hydronium ion concentration of a 0.050 molar solution of HOCl. 3.9 x 10-5 M 2. Methylamine CH3NH2, is a weak base that ionizes in solution as shown by the following equation. CH3NH2 + H2O ↔ CH3NH3+ + OH‐ At 25ºC the percentage ionization in a 0.160 molar solution of CH3NH2 is 4.7%. Calculate [OH‐] and the pH of a 0.160 molar solution of CH3NH2 at 25ºC. 0.00752 M (b) Calculate the value for Kb, the ionization constant for CH3NH2, at 25ºC. 3.7 x 10‐4 3. The acid ionization constant, Ka, for propanoic acid, C2H5COOH, is 1.3x10‐5. (a) Calculate the hydrogen ion concentration, [H+], in a 0.20‐molar solution of propanoic acid. 0.0016 M (b) Calculate the percentage of propanoic acid molecules that are ionized in the solution in (a). 0.81% (c) What is the ratio of the concentration of propanoate ion, C2H5COO‐, to that of propanoic acid in a buffer solution with a pH of 5.20? 2.1 (a) – + NH (aq) + H O(l) ↔NH (aq) + OH (aq) 3 2 4 4. In aqueous solution, ammonia reacts as represented above. In 0.0180M NH (aq) at 25ºC, the hydroxide ion 3 concentration, [OH‐] is 5.60 x 10‐4. In answering the following, assume that temperature is constant at 25ºC and that volumes are additive. (a) (b) Write the equilibrium‐constant expression for the reaction represented above. Determine the pH of 0.0180M NH (aq). 10.748 (c) Determine the value of the base ionization constant, K , of NH (aq). 1.43 x 10‐5 (d) Determine the percent ionization of NH in 0.0180M NH (aq). 3.11% 3 b 3 3 3