IB Topics 5 & 15 Multiple Choice Practice

IB Topics 5 & 15 Multiple Choice Practice 1. Which statement is correct for this reaction? Fe 2O 3 (s) + 3CO (g) 2Fe (s) + 3CO 2 (g) ΔH = 26.6 kj 13.3 kj are released for every mole of Fe produced. 26.6 kj are absorbed for every mole of Fe produced. 53.2 kj are released for every mole of Fe produced. 26.6 kj are released for every mole of Fe produced. 2. The enthalpy changes for two reactions are given. Br 2 (l) + F 2 (g) 2BrF (g) ΔH = x kj Br 2 (l) + 3F 2 (g) 2BrF 3 (g) ΔH = y kj What is the enthalpy change for the following reaction? BrF (g) + F 2 (g) BrF 3 (g) x y x + y ( x + y) (x y) 3. What is the enthalpy change, in kj, of the following reaction? 3H 2 (g) + N 2 (g) 2NH 3 (g) (6 391) [(3 436) + 945] (3 391) (436 + 945) [(3 436) + 945] + (3 391) (6 391) + [(3 436) + 945] 4. Which expression gives the mass, in g, of ethanol required to produce 683.5 kj of heat upon complete combustion? (M r for ethanol = 46.0, ) 5. Which expression gives the enthalpy change, ΔH, for the thermal decomposition of calcium carbonate? ΔH = ΔH 1 ΔH 2 ΔH = 2ΔH 1 ΔH 2 ΔH = ΔH 1 2ΔH 2 ΔH = ΔH 1 + ΔH 2 1

6. In which order does the oxygen oxygen bond enthalpy increase? H 2O 2 < O 2 < O 3 H 2O 2 < O 3 < O 2 O 2 < O 3 < H 2O 2 O 3 < H 2O 2 < O 2 7. What can be deduced from this reaction profile? The reactants are less stable than the products and the reaction is exothermic. The reactants are less stable than the products and the reaction is endothermic. The reactants are more stable than the products and the reaction is exothermic. The reactants are more stable than the products and the reaction is endothermic. 8. Why is the value of the enthalpy change of this reaction calculated from bond enthalpy data less accurate than that calculated from standard enthalpies of formation? 2C 2H 6(g) + 7O 2(g) 4CO 2(g) + 6H 2O(g) All the reactants and products are gases. Bond enthalpy data are average values for many compounds. Elements do not have standard enthalpy of formation. Standard enthalpies of formation are per mole. 9. What can be deduced from the facts that ozone absorbs UV radiation in the region of 340 nm and molecular oxygen in the region of 242 nm? The bond between atoms in molecular oxygen is a double bond. The bonds in ozone are delocalized. The bonds between atoms in ozone are stronger than those in molecular oxygen. The bonds between atoms in molecular oxygen need more energy to break. 10. Which statements are correct for ionic compounds? I. Lattice energy increases as ionic radii increase. II. Within the same group, the melting point of salts tends to decrease as the radius of the cation increases. III. Solubility in water depends on the relative magnitude of the lattice energy compared to the hydration energy. I and II only I and III only II and III only I, II and III 11. What is the standard enthalpy of formation, in kj mol 1, of IF (g)? IF 7 (g) + I 2 (s) IF 5 (g) + 2IF (g) ΔH = 89 kj ΔH (IF 7) = 941 kj mol 1 ΔH (IF 5) = 840 kj mol 1 190 95 +6 +95 2

12. The combustion of glucose is exothermic and occurs according to the following equation: C 6H 12O 6 (s) + 6O 2 (g) 6CO 2 (g) + 6H 2O (g) Which is correct for this reaction? 13. Which equation represents the lattice enthalpy of magnesium sulfide? MgS (s) Mg (g) + S (g) MgS (s) Mg + (g) + S (g) MgS (s) Mg 2+ (g) + S 2 (g) MgS (s) Mg (s) + S (s) 14. The enthalpy change for the dissolution of NH 4NO 3 is +26 kj mol 1 at 25 Which statement about this reaction is correct? The reaction is exothermic and the solubility decreases at higher temperature. The reaction is exothermic and the solubility increases at higher temperature. The reaction is endothermic and the solubility decreases at higher temperature. The reaction is endothermic and the solubility increases at higher temperature. 15. Which equation represents enthalpy of hydration? Na(g) Na + (aq) + e Na + (g) Na + (aq) NaCl(s) Na + (g) + Cl (g) NaCl(s) Na + (aq) + Cl (aq) 16. Which combination of ΔH θ and ΔS θ will result in a non-spontaneous reaction at all temperatures? 17. Which ion s hydration energy is the most exothermic? Li + Na + Br I 3

18. The Born-Haber cycle for potassium oxide is shown below: Which expression represents the lattice enthalpy in kj mol 1? 361 + 428 + 838 + 612 ( 361) + 428 + 838 + 612 361 + 428 + 838 612 ( 361) + 428 + 838 612 19. Which change of state is exothermic? CO 2(s) CO 2(g) H 2O(l) H 2O(g) NH 3(g) NH 3(l) Fe(s) Fe(l) 20. The C=N bond has a bond length of 130 pm and an average bond enthalpy of 615kJmol -1. Which values would be most likely for the C-N bond? 21. When 25.0cm 3 0.100moldm 3 NaOH(aq) is mixed with 25.0cm 3 0.100moldm 3 HCl(aq) at the same temperature, a temperature rise, T, is recorded. What is the expression, in kj mol 1, for the enthalpy of neutralisation? (Assume the density of the mixture = 1.00 g cm 3 and its specific heat capacity=4.18kjkg 1 K 1 =4.18Jg 1 K 1 ) 22. Hydrazine reacts with oxygen. N 2H 4(l) + O 2(g) N 2(g) + 2H 2O(l) ΔH θ = -623 kj What is the standard enthalpy of formation of N 2H 4(l) in kj? The standard enthalpy of formation of H 2O(l) is -286 kj. -623-286 -623 + 572-572 + 623-286 + 623 23. What is the enthalpy of formation of ethyne, in kjmol 1, represented by the arrow Y on the diagram? 788 286+1301 788 286 1301 +788+286 1301 +788+286+1301 4

24. In which reaction do the reactants have a lower potential energy than the products? CH 4(g) + 2O 2(g) CO 2(g) + 2H 2O(g) HBr(g) H(g) + Br(g) Na + (g) + Cl - (g) NaCl(s) NaOH(aq) + HCl(aq) NaCl(aq) + H 2O(l) 25. Which equation represents the average bond enthalpy of the Si H bond in SiH 4? SiH 4(g) SiH 3(g)+H(g) SiH 4 (g) Si(g) + H(g) SiH 4(g) SiH 3(g) + H 2(g) SiH 4 (g) Si(g) + 4H(g) 26. 5.35g of solid ammonium chloride, NH 4Cl(s), was added to water to form 25.0g of solution. The maximum decrease in temperature was 14 K. What is the enthalpy change, in kjmol -1, for this reaction? (Molar mass of NH 4Cl = 53.5gmol -1 ; the specific heat capacity of the solution is 4.18 Jg -1 K -1 ) 27. The equation for the formation of ethyne is: 2C(s) + H 2 (g) C 2H 2 (g) What is the enthalpy change, in kj, for this reaction using the enthalpy of combustion data below? 2 ( 394) + ( 572) ( 2602) 2 ( 394) + ( 572) ( 2602) 2 ( 394) + ( 572) + ( 2602) 2 ( 394) + ( 572) + ( 2602) 28. Which transition represents an enthalpy of hydration? 2H 2O (l) H 3O + (aq) + OH (aq) NaCl (s) Na + (aq) + Cl (aq) K +( s) K + (aq) K + (g) K + (aq) 29. Which represents the enthalpy change of hydration of the chloride ion? 5

30. What are the signs for the entropy changes associated with this reaction? H 2O(g) H 2O(l) 31. Which ionic compound has the largest value of lattice enthalpy? MgS MgO CaBr 2 NaF 32. Which processes are exothermic? I. II. III. I and II only I and III only II and III only I, II and III 33. Which equation corresponds to the bond enthalpy of the H I bond? 34. Which combination is correct for the standard enthalpy change of neutralization? 35. When four moles of aluminium and four moles of iron combine with oxygen to form their oxides, the enthalpy changes are 3338 kj and 1644 kj respectively. What is the enthalpy change, in kj, for the reduction of one mole of iron(iii) oxide by aluminium? 6

36. Which enthalpy changes can be calculated using only bond enthalpy data? I. II. III. I and II only I and III only II and III only I, II and III 37. The same amount of heat energy is added to 1.00 g of each substance. Which statement is correct if all the substances are at the same temperature before the heat energy is added? Copper will reach the highest temperature. Water will reach the highest temperature. All four substances will reach the same temperature. Aluminium will reach a higher temperature than sodium chloride. 38. Which equation represents the standard enthalpy of formation of liquid methanol? 39. Which species are arranged in order of increasing entropy? 40. Which combination of and values corresponds to a non-spontaneous reaction at all temperatures? 7

41. Which equation represents the standard enthalpy change of formation,, of tetrachloromethane? 42. What is the correct order for increasing lattice enthalpy? 43. Which combinations of values will result in a spontaneous reaction? I and II only I and III only II and III only I, II and III 44. The enthalpy change for the reaction between zinc metal and copper(ii) sulfate solution is. Which statement about this reaction is correct? The reaction is endothermic and the temperature of the reaction mixture initially rises. The reaction is endothermic and the temperature of the reaction mixture initially drops. The reaction is exothermic and the temperature of the reaction mixture initially rises. The reaction is exothermic and the temperature of the reaction mixture initially drops. 45. Consider the following equations. What is the enthalpy change of the reaction: 46. Which statement is correct for the reaction with this enthalpy level diagram? Heat energy is released during the reaction and the reactants are more stable than the products. Heat energy is absorbed during the reaction and the reactants are more stable than the products. Heat energy is released during the reaction and the products are more stable than the reactants. Heat energy is absorbed during the reaction and the products are more stable than the reactants. 8

47a. The enthalpy changes of three reactions are given below. What is the enthalpy change for the following reaction? 47b. The specific heat capacities of two substances are given in the table below. Which statement is correct? More heat is needed to increase the temperature of 50 g of water by 50 C than 50 g of ethanol by 50 If the same heat is supplied to equal masses of ethanol and water, the temperature of the water increases more. If equal masses of water at 20 C and ethanol at 50 C are mixed, the final temperature is 35 C. If equal masses of water and ethanol at 50 C cool down to room temperature, ethanol liberates more heat. 48. The table shows information about temperature increases when an acid and an alkali are mixed. What is the value of? 49. What is the value of for the exothermic reaction represented by the diagram below? 9

50. What is the temperature rise when 2100 J of energy is supplied to 100 g of water? (Specific heat capacity of water.) 5 C 278 K 0.2 C 20 C 51. Which processes have a negative value for? I. II. III. I and II only I and III only II and III only I, II and III 52. The Born-Haber cycle for the formation of magnesium oxide is shown below. What is a correct description of the steps X, Y and Z in this cycle? 10

53. Consider the values of and À for the reaction of nitrogen with oxygen at 298 K. Which statement is correct for this reaction? is positive at all temperatures. is negative at all temperatures. is positive at high temperatures. is positive at low temperatures. 54. What is the correct definition of lattice enthalpy? Enthalpy change when one mole of a solid ionic compound is separated into gaseous ions. Enthalpy change when one mole of a solid ionic compound is separated into its ions in their standard state. Enthalpy change when one mole of a solid ionic compound is formed from gaseous elements. Enthalpy change when one mole of a compound is formed from the elements in their standard states. 55. Which reaction has the greatest increase in entropy? 56. Which change must be negative when a reaction occurs spontaneously? 57. Which combination of enthalpy change and entropy change produces a non-spontaneous reaction at all temperatures? 58. Which equation represents the lattice enthalpy of calcium chloride? 11

59. In which reaction will the entropy of the system increase significantly? 60. Which equation represents the second electron affinity of oxygen? 61. Which processes are exothermic? I. II. III. I and II only I and III only II and III only I, II and III 62. Consider the following two equations. What is, in kj, for the following reaction? 63. Which statement is correct for the enthalpy level diagram shown? The reaction is exothermic and the products are more stable than the reactants. The reaction is exothermic and the sign of the enthalpy change is positive. The reaction is endothermic and the sign of the enthalpy change is negative. The reaction is endothermic and the products are more stable than the reactants. 12

64. Which combination is correct about the energy changes during bond breaking and bond formation? 65. Which statements are correct for an exothermic reaction? I. The products are more stable than the reactants. II. The enthalpy change,, is negative. III. The temperature of the surroundings increases. I and II only I and III only II and III only I, II and III 66. The specific heat capacity of aluminium is. What is the heat energy change, in J, when 10.0 g of aluminium is heated and its temperature increases from 15.0 Cto 35.0 C? +180 +315 +1800 +2637 67. The reaction between methane and oxygen is exothermic. Which statement is correct? The total bond enthalpies of the reactants are less than the total bond enthalpies of the products. The total bond enthalpies of the reactants are greater than the total bond enthalpies of the products. The total energy released during bond formation is less than the total energy absorbed during bond breaking. The activation energy is the difference between the total bond enthalpies of the products and the total bond enthalpies of the reactants. 68. Which processes are exothermic? I. II. III. I and II only I and III only II and III only I, II and III 13

69. Consider the following two equations. What is, in kj, for the following reaction? 70. Which ionic compound has the most endothermic lattice enthalpy? Sodium chloride Sodium oxide Magnesium chloride Magnesium oxide 71. Which processes are predicted to have a positive entropy change,? I. II. III. I and II only I and III only II and III only I, II and III 72. Which combination of and signs will always result in a spontaneous reaction at all temperatures? 73. Which process is endothermic? 74. Which combination of ions will give the greatest absolute lattice enthalpy? A small positive ion with a high charge and a small negative ion with a high charge A small positive ion with a low charge and a small negative ion with a low charge A large positive ion with a high charge and a large negative ion with a high charge A large positive ion with a low charge and a small negative ion with a low charge 14

75. Which process would be expected to have a value which is negative? 76. When solid potassium chlorate,, dissolves in distilled water the temperature of the solution decreases. What are the signs of, and for this spontaneous process? 77. Enthalpy changes of reaction are provided for the following reactions. What is the enthalpy change, in, for the reaction between ethene and hydrogen? 137 33 +33 +137 78. Which reaction has an enthalpy change equal to the standard enthalpy change of combustion? 79. Which reactions/processes have a positive entropy change,? I. II. III. I and II only I and III only II and III only I, II and III 15

80. Which compound has the most positive lattice enthalpy of dissociation? NaCl NaBr 81. Which combination is correct for the exothermic reaction that occurs between zinc and copper sulfate solution. 82. A 5.00 g sample of a substance was heated from 25.0 C to 35.0 C using of energy. What is the specific heat capacity of the substance in? 2.00 4.00 83. Using the equations below: what is, in kj, for the following reaction? 214 72 +72 +214 16

84. A simple calorimeter was set up to determine the enthalpy change occurring when one mole of ethanol is combusted. The experimental value was found to be (at 298 K and ). During the experiment some black soot formed. Which statements are correct? I. The percentage error for the experiment can be calculated as follows:. The Data Booklet value is II. The difference between the two values may be due to heat loss to the surroundings. III. The black soot suggests that incomplete combustion occurred. I and II only I and III only II and III only I, II and III 85. Consider the equations: What is, in kj, for the following reaction? 86. Consider the following information: What happens to the spontaneity of this reaction as the temperature is increased? The reaction becomes more spontaneous as the temperature is increased. The reaction becomes less spontaneous as the temperature is increased. The reaction remains spontaneous at all temperatures. The reaction remains non-spontaneous at all temperatures. 87. Which equation represents the electron affinity of chlorine? 17

88. During which process is there a decrease in the entropy of the system? 89. A student measured the temperature of a reaction mixture over time using a temperature probe. By considering the graph, which of the following deductions can be made? I. The reaction is exothermic. II. The products are more stable than the reactants. III. The reactant bonds are stronger than the product bonds. I and II only I and III only II and III only I, II and III 90. Which factors will increase the entropy of this system? I. Increasing the temperature without changing the volume of the container. II. Decreasing the concentration of the gas without changing the volume of the container. III. Increasing the pressure without changing the volume of the container. I and II only I and III only II and III only I, II and III 91. The rate expression for the reaction between iodine and propanone with an acid catalyst is found to be: What is the overall order of the reaction? 0 1 2 3 18

92. Which reaction has the greatest increase in entropy? 93. Consider the two reactions involving iron and oxygen. What is the enthalpy change, in kj, for the reaction below? 94. Which equation corresponds to the lattice enthalpy for silver iodide, AgI? 95. Which ionic compound has the greatest lattice enthalpy? MgO CaO NaF KF 96. Which equation represents the bond enthalpy for the H Br bond in hydrogen bromide? 97. Which change will not increase the entropy of a system? Increasing the temperature Changing the state from liquid to gas Mixing different types of particles A reaction where four moles of gaseous reactants changes to two moles of gaseous products 19

98. calculations predict that a reaction is always spontaneous for which of the following combinations of and? and and and and 99. Which statement is correct given the enthalpy level diagram below? The reaction is endothermic and the products are more thermodynamically stable than the reactants. The reaction is exothermic and the products are more thermodynamically stable than the reactants. The reaction is endothermic and the reactants are more thermodynamically stable than the products. The reaction is exothermic and the reactants are more thermodynamically stable than the products. 100. Which equation represents the standard enthalpy change of formation, f, of tetrachloromethane? C(g)+4Cl(g) CCl4(g) C(s)+4Cl(g) CCl4(l) C(g)+2Cl2(g) CCl4(g) C(s)+2Cl2(g) CCl4(l) 20

1. A 2. C 3. D 4. C 5. A 6. B 7. A 8. B 9. D 10. C 11. B 12. A 13. C 14. D 15. B 16. A 17. A 18. B 19. C 20. A 21. D 22. C 23. A 24. B 25. B 26. C 27. A 28. D 29. A 30. A 31. B 32. D 33. D 34. A 35. C 36. B 37. A 38. D 39. C 40. B 41. D 42. B 43. B 44. C 45. A 46. B 47a. D b. A 48. B 49. B 50. A 51. B 52. C 53. D 54. A 55. C 56. B 57. A 58. B 59. A 60. D 61. B 62. A 63. A 64. C 65. D 66. A 67. A 68. B 69. A 70. D 71. C 72. D 73. B 74. A 75. A 76. B 77. A 78. B 79. A 80. C 81. C 82. D 83. B 84. C 85. D 86. A 87. A 88. C 89. A 90. A 91. C 92. C 93. A 94. D 95. A 96. A 97. D 98. D 99. B 100. D 21