CHEM 102: Sample Test 5 CHAPTER 171. When H2SO4 is dissolved in water, which species would be found in the water at equilibrium in measurable amounts? a. H2SO4 b. H3SO4 + c. HSO4 - d. SO4 -2 e. OH- 2. Which of the following is the net ionic equation for the reaction that occurs during the titration of nitrous acid with potassium hydroxide? a) HNO2 + K+ + OH- Æ KNO2 + H2O b) HNO2 + H2O Æ NO2- + H3O+ c) HNO2 + KOH Æ K+ + NO2- + H2O d) HNO2 + OH- Æ NO2- + H2O e) H+ + OH- Æ H2O 3. What is the pH of a solution that is 0.2 M in acetic acid (Ka = 1.8 x 10-5) and 0.2 M in sodium acetate? a) 4.7 b) 9.3 c) 7.0 d) 5.4 e) 8.6 4. Given 0.015 moles of NaC2H3O2and 0.05 moles of HC2H3O2 dissolved in water, what is the pH? pKa for acetic acid is 4.74. a. 5.22 b. 4.74 c. 4.22 d. 1.30 e. Cannot determine 5. If 50 ml of a 0.01 M HCl solution is titrated with a 0.01 M NaOH solution, what will be the initial pH and the pH at the endpoint. a. 2 and 3.5 b. 2 and 7 c. 3.30 and 7 d. 12 and 7 e. None of these 6. What is the pH of a 1.0 M aqueous solution of NaCl? a) 7.0 b) greater than 7.0 c) less than 7.0 d) there is not enough information given 7. A 50.00-mL sample of 0.100 M KOH is being titrated with 0.100 M HNO3. Calculate the pH of the solution after 52.00 mL of HNO3 is added. a) 6.50 b) 3.01 c) 2.71 d) 2.41 e) none of these 8. If the following substance is dissolved in pure water, will the solution be acidic, neutral, or basic? solid sodium carbonate: (Na2CO3). a) acidic b) neutral c) basic 9. The Henderson-Hasselbach equation can be used to determine several factors. Which of the following can be determined? a. the pH for a solution of a strong acid and its conjugate base b. the pH for a strong base that has been partially titrated c. the mole ratio needed to make a buffer solution having a known pH d. the pKa of an equimolar mixture of an unknown weak acid and its conjugate base without knowing the pH e. the change in pH if some acid or base is added to a buffered solution 10. A 1 Liter buffered solution was prepared by dissolving 1.0 mole of NH3 and 1.5 mole of NH4Cl in water. The pH of this solution would be: (Kb = 1.8 x 10-5) a. 11.0 b. 9.0 c. 7.0 d. 4.0 e. none of the above 11. The salt that forms an alkaline (basic) aqueous solution is a. KNO3. b. NH4Cl. c. NaC2H3O2. d. NaCl.12. A weak acid that has different colors for acid and its conjugate base can be used as a. an salt. b. an indicator. c. a buffer. d. a base. 13. Give the pH value of a solution 0.10 M in acetic acid (Ka = 1.8 x 10-5) and 0.05 M in sodium acetate: a. 1.8 b. 2.4 c. 4.7 d. 4.4 e. 5 14. Methyl violet is an indicator used in acid-base titrations. Its acid form, HIn, is red, while its conjugate base from, In-, is yellow. The color change occurs in the pH range 0.00-1.6. In a solution of pH = 6.00 the color of the indicator will be a. red b. yellow c. orange d. colorless e. blue 15. In the titration of a weak acid HA with 0.100 M NaOH, the stoichiometric point is known to occur at a pH value of approximately 11. Which of the following indicators would be best to use to mark the endpoint of this titration? a) an indicator with Ka = 10-10 b) an indicator with Ka = 10-8 c) an indicator with Ka = 10-14 d) an indicator with Ka = 10-11 e) an indicator with Ka = 10-12 16. Calculate the pH of an aqueous solution of 2.0 M NH4Cl (Kb for NH3 =1.8 x 10-5). Choose your answer from the following pH ranges: a. pH = 0.00-2.99 b. pH = 3.00-5.99 c. pH = 6.00-8.99 d. pH = 9.00-10.99 e. pH = 11.00-14.00 17. Assume that an indicator works BEST when the equivalent point of a titration comes in the middle of the indicator range. Which of the following indicators would be the best for a titration of 35.00 mL of 0.10 M HC2H3O2 (Ka=1.8 x 10-5) with 35.00 mL 0.10 M NaOH? a. methyl violet 0.0-1.6 b. methyl orange 3.2-4.4 c. bromocresol green 3.8-5.4 d. methyl red 4.8-6.0 e. phenolphthalein 8.2-10.0 18. Given a equimolar mixture of Benzoic acid and sodium benzoate what would be the pH of the solution? Ka of HC7H5O2 = 6.28 x 10-5 a. 4.20 b. 9.80 c. 2.10 d. 6.28 e. Cannot determine 19. A weak monoprotic acid (HA) is 1.41% dissociated in a 1.0 M solution. The Ka for this acid is a. 4.0 x 10-6. b. 5.6 x 10-5. c. 2.0 x 10-4. d. 9.9 x 10-3. 20. Buffer solution is one which a. contains the maximum amount of solute possible for a particular temperature. b. contains more than the expected amount of solute for a particular temperature and is therefore unstable. c. resists changes in pH upon addition of acid or base. d. contains an equal number of hydronium and hydroxide ions. e. changes color upon addition of strong base. 21. Which pair of compounds could be used to make a buffer solution? a. NaCl/HCl b. (NH4)2SO4/H2SO4 c. NaCH3COO/CH3COOH d. K3PO4/KH2PO4 e. KOH/KBr 22. A salt which can be used to make a buffer with formic acid, HCOOH, isa. NH4COOH b. KCOOH c. NaCl d. Na2CO3 e. (NH4)3PO4 23. Which two of the following compounds in aqueous solution would make an effective buffer solution? HNO3 KNO3 CH3COOH NH4NO3 NH3 a. HNO3 & NH4NO3 b. HNO3 & KNO3 c. CH3COOH & NH3 d. NH3 & NH4NO3 e. CH3COOH & HNO3 24. Which combination of solutions is the best choice for making a buffer solution? a. equal volumes of 0.1 M formic acid and 0.1 M sodium formate b. equal volumes of 0.05 M hydrochloric acid and 0.075 ammonium chloride c. equal volumes of 0.1 M sulfuric acid and 0.001 M sodium sulfate d. equal volumes of 1 M acetic acid and 0.005 M sodium acetate e. equal volumes of 0.5 M nitric acid and 0.5 M sodium hydroxide 25. Calculate the pH of a solution which is 0.05 M in lactic acid and 0.04 M in sodium lactate. The Ka for lactic acid is 1.8 × 10-4. a. 10.35 b. 3.74 c. 3.65 d. 0.097 e. 2.25 × 10-4 26. Calculate the pH of a solution that contains 0.45 M benzoic acid and 0.40 M sodium benzoate. The Ka for benzoic acid is 6.5 × 10-5. a. 7.3 × 10-5 b. 4.53 c. 4.19 d. 4.14 e. 3.79 27.Which formula represents the Henderson-Hasselbach equation for the generic acid HA? a. [HA]][AlogpHapK-+= b. [HA]][AlogapKpH-−= c. pHapK]HA[][Alog-−= d. [HA]][AapKpH-+= e. …