Test: Chemical Equilibrium (Chapter 8)

Multiple Choice Questions

  1. 1. A reaction that can proceed in both forward and reverse directions under given conditions is called:

  2. 2. The reaction 2Na(s) + 2H₂O(l) -> 2NaOH(aq) + H₂(g) is generally considered:

  3. 3. The state reached when the rate of the forward reaction becomes equal to the rate of the reverse reaction is called:

  4. 4. At chemical equilibrium, the concentrations of reactants and products:

  5. 5. Chemical equilibrium is referred to as 'dynamic' because:

  6. 6. The Law of Mass Action relates the rate of reaction to the:

  7. 7. The term 'active mass' in the Law of Mass Action usually refers to:

  8. 8. For the reaction A + B <=> C + D, the rate of the forward reaction (Rf) is given by:

  9. 9. The equilibrium constant, Kc, is defined as the ratio:

  10. 10. For the general reaction aA + bB <=> cC + dD, the correct expression for Kc is:

  11. 11. In the Kc expression, the exponents of the concentration terms correspond to the:

  12. 12. When does the equilibrium constant Kc have no units?

  13. 13. What are the units of Kc for the reaction N₂(g) + 3H₂(g) <=> 2NH₃(g)?

  14. 14. What are the units of Kc for the esterification reaction CH₃COOH + C₂H₅OH <=> CH₃COOC₂H₅ + H₂O?

  15. 15. For the dissociation PCl₅(g) <=> PCl₃(g) + Cl₂(g), if 'a' is initial moles, 'x' is moles dissociated, and 'V' is volume, Kc is proportional to:

  16. 16. For the synthesis of ammonia N₂(g) + 3H₂(g) <=> 2NH₃(g), the Kc expression involves volume (V) as:

  17. 17. Kp is the equilibrium constant expressed in terms of:

  18. 18. The relationship between Kp and Kc is given by:

  19. 19. In the equation Kp = Kc(RT)Δⁿ, Δn represents:

  20. 20. When is Kp equal to Kc for a gaseous reaction?

  21. 21. For the reaction N₂(g) + 3H₂(g) <=> 2NH₃(g), what is the value of Δn?

  22. 22. For the reaction H₂(g) + I₂(g) <=> 2HI(g), what is the relationship between Kp and Kc?

  23. 23. For the reaction PCl₅(g) <=> PCl₃(g) + Cl₂(g), what is the relationship between Kp and Kc?

  24. 24. The magnitude of the equilibrium constant Kc indicates the:

  25. 25. If the reaction quotient (ratio of [Products]/[Reactants] at any time) is less than Kc, the reaction will proceed:

  26. 26. If the reaction quotient is greater than Kc, the reaction will proceed:

  27. 27. A very large value of Kc (e.g., 10⁵⁵ for 2O₃ <=> 3O₂) indicates that:

  28. 28. A very small value of Kc (e.g., 10⁻¹³ for 2HF <=> H₂ + F₂) indicates that:

  29. 29. Le Chatelier's principle states that if a stress is applied to a system at equilibrium, the system will shift to:

  30. 30. For the equilibrium BiCl₃ + H₂O <=> BiOCl(s) + 2HCl, adding more HCl will shift the equilibrium:

  31. 31. For the equilibrium BiCl₃ + H₂O <=> BiOCl(s) + 2HCl, adding more water will shift the equilibrium:

  32. 32. Removing a product from an equilibrium mixture will generally shift the equilibrium:

  33. 33. Changes in pressure or volume significantly affect gaseous equilibria only when:

  34. 34. For the reaction 2SO₂(g) + O₂(g) <=> 2SO₃(g), increasing the pressure (decreasing volume) will shift the equilibrium:

  35. 35. For the reaction PCl₅(g) <=> PCl₃(g) + Cl₂(g), decreasing the pressure (increasing volume) will shift the equilibrium:

  36. 36. For the reaction H₂(g) + I₂(g) <=> 2HI(g), changing the pressure or volume will:

  37. 37. Increasing the temperature of an exothermic reaction at equilibrium will shift the equilibrium:

  38. 38. Increasing the temperature of an endothermic reaction at equilibrium will shift the equilibrium:

  39. 39. For the dissolution of KI in water (KI(s) <=> KI(aq), ΔH = +21.4 kJ/mol), increasing the temperature will:

  40. 40. For substances with negative heats of solution (exothermic dissolution), increasing the temperature will:

  41. 41. What is the effect of adding a catalyst to a system at equilibrium?

  42. 42. The Haber process is used for the industrial synthesis of:

  43. 43. The synthesis of ammonia (N₂ + 3H₂ <=> 2NH₃) is an ___ reaction.

  44. 44. According to Le Chatelier's principle, the yield of ammonia in the Haber process is favoured by:

  45. 45. Why are moderate temperatures (around 400°C) used in the Haber process despite low temperatures favouring yield?

  46. 46. The catalyst typically used in the Haber process is:

  47. 47. How is ammonia separated from the equilibrium mixture in the Haber process?

  48. 48. The Contact process is used for the industrial production of:

  49. 49. The key reversible step in the Contact process is:

  50. 50. The conversion of SO₂ to SO₃ is an ___ reaction.

  51. 51. High yield of SO₃ in the Contact process is favoured by:

  52. 52. The catalyst commonly used in the Contact process is:

  53. 53. Pure water undergoes self-ionization according to the equation:

  54. 54. The ionic product of water, Kw, is defined as:

  55. 55. The value of Kw at 25°C is:

  56. 56. How does the value of Kw change with increasing temperature?

  57. 57. In neutral water at 25°C, the concentration of H⁺ ions is:

  58. 58. In an acidic solution at 25°C:

  59. 59. pH is defined as:

  60. 60. pOH is defined as:

  61. 61. The pH of neutral water at 25°C is:

  62. 62. A solution with pH < 7 is considered:

  63. 63. A solution with pH > 7 is considered:

  64. 64. The relationship between pH and pOH at 25°C is:

  65. 65. If the pH of a solution is 3, what is the pOH at 25°C?

  66. 66. The dissociation constant of a weak acid, Ka, is a measure of its:

  67. 67. For the dissociation HA <=> H⁺ + A⁻, the expression for Ka is:

  68. 68. A smaller value of Ka indicates a ___ acid.

  69. 69. The percentage ionization of a weak acid ___ as the solution becomes more dilute.

  70. 70. The base ionization constant, Kb, measures the strength of a:

  71. 71. For the reaction B + H₂O <=> BH⁺ + OH⁻, the expression for Kb is:

  72. 72. pKa is defined as:

  73. 73. A larger value of pKa indicates a ___ acid.

  74. 74. For a conjugate acid-base pair, the relationship between Ka, Kb, and Kw is:

  75. 75. For a conjugate acid-base pair at 25°C, the relationship between pKa and pKb is:

  76. 76. If an acid has a small Ka value, its conjugate base will have a ___ Kb value.

  77. 77. The suppression of ionization of a weak electrolyte by adding a substance having a common ion is called:

  78. 78. Adding HCl gas to a saturated NaCl solution causes NaCl to precipitate due to:

  79. 79. Adding HCl to a solution of H₂S will ___ the concentration of S²⁻ ions.

  80. 80. Adding NH₄Cl to a solution of NH₄OH will ___ the concentration of OH⁻ ions.

  81. 81. A buffer solution is one that:

  82. 82. An acidic buffer is typically made by mixing:

  83. 83. A basic buffer is typically made by mixing:

  84. 84. Which pair can form an acidic buffer solution?

  85. 85. Which pair can form a basic buffer solution?

  86. 86. In an acetic acid/sodium acetate buffer, added H⁺ ions react primarily with:

  87. 87. In an acetic acid/sodium acetate buffer, added OH⁻ ions react primarily with:

  88. 88. The Henderson-Hasselbalch equation for an acidic buffer is:

  89. 89. The Henderson-Hasselbalch equation for a basic buffer is:

  90. 90. A buffer works best (has maximum buffer capacity) when:

  91. 91. If [salt] = [acid] in an acidic buffer, then:

  92. 92. Buffer capacity refers to the ability of a buffer to:

  93. 93. The solubility product constant, Ksp, applies to:

  94. 94. Ksp represents the equilibrium between:

  95. 95. For the dissolution PbCl₂(s) <=> Pb²⁺(aq) + 2Cl⁻(aq), the Ksp expression is:

  96. 96. For the dissolution Ag₂CrO₄(s) <=> 2Ag⁺(aq) + CrO₄²⁻(aq), the Ksp expression is:

  97. 97. A smaller Ksp value indicates ___ solubility.

  98. 98. If the molar solubility of AgCl is 'S' mol dm⁻³, its Ksp is equal to:

  99. 99. If the molar solubility of PbF₂ is 'S' mol dm⁻³, its Ksp is equal to:

  100. 100. Adding Na₂CrO₄ to a saturated solution of PbCrO₄ will:

Short Answer Questions

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