Practice Examination #8B Name: Date: 1. Equal volumes of 0.5 M HCl and 0.5 M NaOH are mixed. The total volume of the resulting mixture is 2 liters. The ph of the resulting solution is 1. A. 1 B. 2 C. 7 D. 4 2. How many milliliters of 5.0 M NaOH are needed to exactly neutralize 40 milliliters of 2.0 M HCl? 2. A. 8.0 B. 10 C. 16 D. 40 3. What is the hydronium ion concentration of a solution at 298 K whose hydroxide ion concentration is 1 10 8? 3. A. 1 10 6 B. 1 10 7 C. 1 10 8 D. 1 10 14 4. Which statement best describes a solution with a ph of 3? 4. A. It has an H 3 O + ion concentration of 1 10 3 mol/l and is acidic. B. It has an H 3 O + ion concentration of 1 10 3 mol/l and is acidic. C. It has an H 3 O + ion concentration of 1 10 3 mol/l and is basic. D. It has an H 3 O + ion concentration of 1 10 3 mol/l and is basic. page 1
5. As 100 milliliters of 0.10 molar KOH is added to 100 milliliters of 0.10 molar HCl at 298 K, the ph of the resulting solution will 5. A. decrease to 3 B. decrease to 14 C. increase to 7 D. increase to 13 6. If an aqueous solution turns blue litmus red, which relationship exists between the hydronium ion and hydroxide ion concentration? 6. A. [H 3 O + ] > [OH ] B. [H 3 O + ] < [OH ] C. [H 3 O + ] = [OH ] = 10 7 D. [H 3 O + ] = [OH ] = 10 14 7. The [OH ] of a solution is 1 10 6. At 298 K and 1 atmosphere, the product [H 3 O + ][OH ] is 7. A. 1 10 2 B. 1 10 6 C. 1 10 8 D. 1 10 14 8. What is the ph of a 0.00001 molar HCl solution? 8. A. 1 B. 9 C. 5 D. 4 page 2 Practice Examination #8B
9. The results of testing a colorless solution with three indicators are shown in the accompanying table. 9. Indicator red litmus blue litmus phenolphthalein Result blue blue pink Which formula could represent the solution tested? A. NaOH(aq) B. HCl(aq) C. C 6 H 12 O 6 (aq) D. C 12 H 22 O 11 (aq) 10. Base your answer(s) to the following questions on the information below. 10. In liquid water, an equilibrium exists between H 2 O(l) molecules, H + (aq) ions, and OH (aq) ions. A person experiencing acid indigestion after drinking tomato juice can ingest milk of magnesia to reduce the acidity of the stomach contents. Tomato juice has a ph value of 4. Milk of magnesia, a mixture of magnesium hydroxide and water, has a ph value of 10. What is the color of thymol blue indicator when placed in a sample of milk of magnesia? 11. A solution with a ph of 2.0 has a hydronium ion concentration ten times greater than a solution with a ph of 11. A. 1.0 B. 0.20 C. 3.0 D. 20. 12. What is the H 3 O + concentration of a solution that has an OH concentration of 1 10 3 M? 12. A. 1 10 3 M B. 1 10 7 M C. 1 10 11 M D. 1 10 14 M page 3 Practice Examination #8B
13. Base your answer(s) to the following question(s) on the information below. 13. A student, wearing chemical safety goggles and a lab apron, is to perform a laboratory test to determine the ph value of two different solutions. The student is given one bottle containing a solution with a ph of 2.0 and another bottle containing a solution with a ph of 5.0. The student is also given six dropping bottles, each containing a different indicator listed in Reference Table M. Compare the hydronium ion concentration of the solution having a ph of 2.0 to the hydronium ion concentration of the other solution given to the student. 14. Base your answer(s) to the following question(s) on the information below. 14. Some carbonated beverages are made by forcing carbon dioxide gas into a beverage solution. When a bottle of one kind of carbonated beverage is first opened, the beverage has a ph value of 3. State, in terms of the ph scale, why this beverage is classified as acidic. 15. What is the [H 3 O + ] of a 0.001 M NaOH solution? 15. A. 1 10 1 B. 1 10 7 C. 1 10 11 D. 1 10 14 16. As 0.1 M HCl is added to 0.1 M KOH, then ph of the basic solution 16. A. decreases and basicity decreases B. increases and basicity decreases C. decreases and basicity increases D. increases and basicity increases page 4 Practice Examination #8B
17. Base your answer(s) to the following question(s) on the graph below. The graph shows the relationship between ph value and hydronium ion concentration for common aqueous solutions and mixtures. 17. What is the hydronium ion concentration of tomato juice? 18. What is the ph of a 0.001 M KOH solution? 18. A. 14 B. 11 C. 3 D. 7 page 5 Practice Examination #8B
19. In an acid solution, the [H + ] ion is found to be 1 10 2 mole per liter. What is the [OH ] ion in moles per liter? 19. A. 1 10 2 B. 1 10 7 C. 1 10 12 D. 1 10 14 20. A solution has a hydroxide ion concentration of 1 10 5 M. What is the hydrogen ion concentration of the solution? 20. A. 1 10 1 M B. 1 10 5 M C. 1 10 9 M D. 1 10 14 M 21. Base your answer(s) to the following question(s) on the information below. 21. In a titration, 20.0 milliliters of 0.15 M HCl(aq) is exactly neutralized by 18.0 milliliters of KOH(aq). Determine the concentration of the KOH(aq). 22. The ionization constant (K a ) of HF is 6.7 10 4. Which is true in a 0.1 M solution of this acid? 22. A. [HF] is greater than [H + ][F ] B. [HF] is less than [H + ][F ] C. [HF] is equal to [H + ][F ] D. [HF] is equal to [H + ] + [F ] page 6 Practice Examination #8B
23. The ionization constant (K a s) of four acids are shown below. Which K a represents the weakest of these acids? 23. A. K a = 1.0 10 5 B. K a = 1.0 10 4 C. K a = 7.1 10 3 D. K a = 1.7 10 2 24. The diagram here shows an acid being added to a base. As the acid in beaker A is added to the base in flask B, the number of OH ions in flask B 24. A. decreases and the number of Na + ions decreases B. increases and the number of Na + ions decreases C. decreases and the number of Na + ions remains the same D. increases and the number of Na + ions remains the same page 7 Practice Examination #8B
RELATIVE STRENGTHS OF ACIDS IN AQUEOUS SOLUTION AT 1 atm AND 298 K Conjugate Pairs ACID BASE K a HI = H + + I very large HBr = H + + Br very large HCl = H + + Cl very large HNO 3 = H + + NO 3 very large H 2 SO 4 = H + + HSO 4 large H 2 O + SO 2 = H + + HSO 3 1.5 10 2 HSO 4 = H + + SO 2 4 1.2 10 2 H 3 PO 4 = H + + H 2 PO 4 7.5 10 3 Fe(H 2 O) 3+ 6 = H + + Fe(H 2 O) 5 (OH) 2+ 8.9 10 4 HNO 2 = H + + NO 2 4.6 10 4 HF = H + + F 3.5 10 4 Cr(H 2 O) 3+ 6 = H + + Cr(H 2 O) 5 (OH) 2+ 1.0 10 4 CH 3 COOH = H + + CH 3 COO 1.8 10 5 Al(H 2 O) 3+ 6 = H + + Al(H 2 O) 5 (OH) 2+ 1.1 10 5 H 2 O + CO 2 = H + + HCO 3 4.3 10 7 HSO 3 = H + + SO 2 3 1.1 10 7 H 2 S = H + + HS 9.5 10 8 H 2 PO 4 = H + + HPO 2 4 6.2 10 8 NH + 4 = H + + NH 3 5.7 10 10 HCO 3 = H + + CO 2 3 5.6 10 11 HPO 2 4 = H + + PO 3 4 2.2 10 13 HS = H + + S 2 1.3 10 14 H 2 O = H + + OH 1.0 10 14 OH = H + + O 2 < 10 36 NH 3 = H + + NH 2 very small Note: H + (aq) = H 3 O + Sample equation: HI + H 2 O = H 3 O + + I 25. Based on Reference Table L, which of the following species is the strongest electrolyte? 25. A. HF B. H 2 S C. HNO 3 D. HNO 2 page 8 Practice Examination #8B
26. Given the reaction: 26. HNO 2 (aq) H + (aq) + NO 2 (aq) The ionization constant, K a, is equal to A. [HNO 2 ] [H + ][NO 2 ] B. [H + ][NO 2 ] [HNO 2 ] C. [NO 2 ] [H + ][HNO 2 ] D. [H + ][HNO 2 ] [NO 2 ] 27. Which of the following ionization constants (K a ) represents the strongest acid? 27. A. K a = 1 10 14 B. K a = 1 10 7 C. K a = 1 10 4 D. K a = 1 10 2 28. Given the reaction: 28. The ionization constant K a is equal to H 3 PO 4 (aq) H + (aq) + H 2 PO 4 (aq) A. [H + ][H 2 PO 4 ] [H 3 PO 4 ] B. [H 3 PO 4 ] [H + ][H 2 PO 4 ] C. [H + ][H 3 PO 4 ] [H 2 PO 4 ] D. [H 2 PO 4 ] [H + ][H 3 PO 4 ] page 9 Practice Examination #8B
29. When tested, a solution turns red litmus to blue. This indicates that the solution contains more 29. A. H + ions than OH ions B. H 3 O + ions than OH ions C. OH ions than H 3 O + ions D. H + and OH ions than H 2 O molecules 30. Which solution can turn phenolphthalein pink? 30. A. CH 3 OH(aq) B. CH 3 COOH(aq) C. HCl(aq) D. NaOH 31. Red litmus will turn blue when placed in an aqueous solution of 31. A. HCl B. CH 3 COOH C. CH 3 OH D. NaOH 32. Red litmus will turn blue when placed in an aqueous solution of 32. A. HCl B. CH 3 COOH C. CH 3 OH D. NaOH page 10 Practice Examination #8B
33. The diagram pictured shows NaOH(aq) being added to HCl(aq). A few drops of phenolphthalein were added to the flask before the titration was started. The endpoint in this titration is reached when the solution in the flask appears 33. A. pink B. colorless C. blue D. yellow 34. Given the reaction: 34. Which is a conjugate acid-base pair? NH 3 (g) + H 2 O(l) NH + 4 (aq) + OH (aq) A. H 2 O(l) and NH + 4 (aq) B. H 2O(l) and NH 3 (g) C. NH 3 (g) and OH (aq) D. NH 3 (g) and NH + 4 (aq) 35. A 9.0 milliliter sample of HCl solution is exactly neutralized by 6.0 milliliters of a 3.0 M NaOH solution. What is the concentration of the HCl solution? 35. A. 1.0 M B. 2.0 M C. 1.8 M D. 1.5 M page 11 Practice Examination #8B
36. How many moles of HCl can be neutralized by 0.1 liter of 0.5 M NaOH? 36. A. 0.1 B. 0.05 C. 0.5 D. 0.4 37. Given the following titration data: 37. Volume of base (KOH) = 40.0 ml Molarity of base = 0.20 M Volume of acid (HCl) added = 20.0 ml The concentration of HCl required for the acid to neutralize the base is A. 1.0 M B. 0.20 M C. 0.10 M D. 0.40 M 38. What is the molarity of a KOH solution if it requires 20 milliliters of 2.0 M HCl to exactly neutralize 20 milliliters of the KOH solution? 38. A. 1.0 M B. 2.0 M C. 10 M D. 20 M 39. How many milliliters of 2.5 M HCl are required to exactly neutralize 15 milliliters of 5.0 M NaOH? 39. A. 10 B. 20 C. 30 D. 40 page 12 Practice Examination #8B
40. How many milliliters of 0.20 molar KOH solution are needed to exactly neutralize 20 milliliters of a 0.50 molar HCl solutions? 40. A. 50 B. 25 C. 10 D. 4.0 41. Which formula correctly represents the compound calcium hydroxide? 41. A. CaOH B. Ca 2 OH C. CaOH 2 D. Ca(OH) 2 42. The formula for the calcium salt of sulfuric acid is 42. A. CaS B. Ca 2 S C. CaSO 4 D. Ca 2 SO 4 43. Which is the correct formula for iron (III) sulfate? 43. A. Fe 3 SO 4 B. Fe 2 SO 4 C. Fe(SO4) 3 D. Fe 2 (SO 4 ) 3 page 13 Practice Examination #8B
44. Red Cabbage ph Indicator Investigation 44. Red cabbage contains a water-soluble pigment. In a highly acidic solution, the pigment turns bright red, and in a moderately acidic solution, it turns pinkish. In a highly basic solution, the pigment turns yellow, and in a moderately basic solution, it turns bluish. A student makes a ph indicator from red cabbage that has a reddish-purple color with a ph of approximately 7. The student pours the same amount of the cabbage solution into each of four different beakers. He then adds a different household solution to each of the four beakers until a color change is obtained. His results are shown in the table below. Household Solution lemon juice club soda window cleaner drain cleaner Color of Mixture bright pink light pink light blue greenish-yellow The student finds the following chart online from someone else s cabbage ph indicator investigation. ph 2 4 6 8 10 12 Color red pink purple blue green yellow Comparing his results to the chart above, what logical conclusion can the student make regarding the substances he tested? A. Lemon juice has a ph between 0 and 2. B. Drain cleaner has a ph between 10 and 12. C. Window cleaner and club soda are both neutral solutions. D. Window cleaner can be used to completely neutralize drain cleaner. 45. Based on the information in the passage, which household solution has the lowest ph? 45. A. club soda B. lemon juice C. drain cleaner D. window cleaner page 14 Practice Examination #8B
46. The equation below shows ammonia dissolving in water. 46. NH 3 (aq) + H 2 O(l) NH + 4 (aq) + OH (aq) Why is water considered an acid when ammonia is dissolved in it? A. Water acts as a proton donor. B. Water acts as a proton acceptor. C. Water contains hydrogen atoms. D. Water has a 2 : 1 ratio of hydrogen to oxygen. 47. A water sample was found to have a ph of 6 at 25 C. What is the hydroxide concentration in the water sample? 47. A. 1 10 8 M B. 6 10 8 M C. 1 10 6 M D. 6 10 6 M page 15 Practice Examination #8B