1. Hydrogen cyanide is used in the manufacture of clear plastics such as Lucite or Plexiglas. It is prepared from ammonia (NH₃) and natural gas (CH₄).
   2NH₃(g) + 3O₂(g) + 2CH₄ --> 2HCN(g) + 6H₂O(g)

   The reaction evolves 939 kJ of heat per 2 mol HCN formed. What is the value of q for this reaction, and is the reaction endothermic or exothermic?

   1. +469.5 kJ ; endothermic
   2. +939 kJ ; endothermic
   3. -939 kJ ; exothermic
   4. -469.5 kJ ; exothermic
   5. -1879 kJ ; exothermic

2. The enthalpy change for the reaction between W(s) and C(graphite) is difficult to measure directly because the reaction occurs at 1400^oC:
   W(s) + C(graphite) --> WC(s)

   However, the heats of combustion of the elements and of tungsten carbide can be measured and are given below:

   2W(s) + 3O2(g) --> 2WO3(s)	H = -1680.6 kJ
   C(graphite) + O2(g) --> CO2(g)	H = -393.5 kJ
   2WC(s) + 5O2(g) --> 2WO3(s) + 2CO2(g)	H = -2391.6 kJ

   The enthalpy of reaction, H, for the formation of tungsten carbide, WC(s), from the elements is:

   1. -3.8 kJ
   2. -38.0 kJ
   3. -380.0 kJ
   4. +380.0 kJ
   5. none of these

3. Suppose you have a balloon of given volume, V₁, containing a gas at temperature, T₁. When you place the balloon in a colder room at temperature, T₂, the balloon's temperature starts to drop. What are the signs of the system's q, w, and E for this process?
   1. +q, +w, +E
   2. -q, -w, -E
   3. -q, -w, +E
   4. +q, -w, -E
   5. -q, +w, -E

4. When burned in oxygen, 10.0 g of phosphorus generated enough heat to raise the temperature of 2950 g of water from 18.0^oC to 38.0^oC. The heat of formation of P₄O₁₀ from P₄(s) and O₂(g) is:
   1. -3.06 kJ mol^-1
   2. -30.6 kJ mol^-1
   3. -306 kJ mol^-1
   4. -3060 kJ mol^-1
   5. -6120 kJ mol^-1

5. Calculate the heat of combustion per mole of glucose(s), C₆H₁₂O₆(s).
   1. -2813 kJ/mole
   2. -1273 kJ/mole
   3. -281.3 kJ/mole
   4. -17.01 kJ/mole
   5. -4.00 kJ/mole

6. The melting of ice at body temperature is an endothermic process:
   H₂O(s) --> H₂O(l) ; H = +6.0 kJ/mole

   Thus eating ice counteracts the exothermic processes of metabolizing food. How much ice (in grams) would you have to eat to counteract the energy gained by eating 1.00 oz of peanuts (13 kJ/g)? [1 oz = 28.3 g]

   1. 61 g
   2. 78 g
   3. 110 g
   4. 370 g
   5. 1100 g

7. A gas is allowed to expand at constant temperature from a volume of 1.0 L to 10.1 L against an external pressure of 0.50 atm. If the gas absorbs 250 J of heat from the surroundings, what are the values of q, w, and E?

   	q	w	E
   (a)	250 J	-460 J	-210 J
   (b)	-250 J	-460 J	-710 J
   (c)	250 J	460 J	710 J
   (d)	-250 J	460 J	245 J
   (e)	250 J	-4.55 J	245 J

8. In the reaction,
   CH₄(g) + 2O₂(g) --> 2H₂O(l) + CO₂(g) ; H^o_rxn = 890.4 kJ

   At 1.0 atm and 273 K (STP), how much work is involved per mole of CH₄(g) with the volume change that occurs upon reaction. Ignore the small volume of the liquid.

   1. -4.5 kJ
   2. -2.2 kJ
   3. 2.2 kJ
   4. 4.5 kJ
   5. 6.8 kJ

9. In which of the following general chemical systems is work done on the surroundings and heat transferred from the surroundings to the system?
   1. A(g) + B(g) --> AB(g) ; q = -
   2. AB(g) --> A(g) + B(g) ; q = +
   3. AB(g) + CD(g) --> CB(g) + AD(g) ; q = +
   4. A(g) + A(g) --> A₂(g) ; q = +
   5. B₂(g) --> 2B(g) ; q = -

10. A certain process has E > 0. Which of the following conditions must be obeyed?
    1. q > 0
    2. w > 0
    3. q + w > 0
    4. q > 0 if |q| > |w| { |x| = absolute value of x}
    1. I, II, III, IV
    2. I, II, III
    3. III and IV
    4. I and II
    5. II and III

11. A coffee-cup calorimeter is calibrated by adding 1840 J of heat to the water in the calorimeter and measuring a 1.72^oC rise in temperature. When some NH₄NO₃(s) is added to the same water in the calorimeter, the temperature falls by 1.04^oC. Calculate the enthalpy change due to the dissolving of this NH₄NO₃(s).
    1. -1110 J
    2. -1250 J
    3. +1110 J
    4. +1910 J
    5. +3040 J

12. Which of the following statements is true?
    1. q = H at constant P; q = E at constant T
    2. q = H at constant T; q = E at constant V
    3. q = H at constant V; q = E at constant P
    4. q = H at constant P; q = E at constant V
    5. q = H = E at constant P or at constant V

13. An ice cube at 0^oC weighing 9.0 g is dropped into an insulated vessel containing 72 g of water at 50^oC. What is the final temperature of the water after the ice has melted and a constant temperature has been reached? The latent heat of fusion of ice is 6.01 kJ/mol, the molar heat capacity of H₂O is 75.4 J/mol K.
    1. 44^oC
    2. 40^oC
    3. 36^oC
    4. 32^oC
    5. 28^oC

14. Using the following data:

    N2(g) + 3O2(g) + H2(g) --> 2HNO3(aq)	H = -414.8 kJ
    N2O5(g) + H2O(g) --> 2HNO3(aq)	H = 218.4 kJ
    2H2O(g) --> 2H2(g) + O2(g)	H = 483.6 kJ

    Determine H for the reaction:

    2N₂O₅(g) --> 2N₂(g) + 5O₂(g)
    1. 149.6 kJ
    2. 90.8 kJ
    3. -876.4 kJ
    4. 782.8 kJ
    5. 1750 kJ

15. H^o of which of the following reactions is equal to the standard enthalpy of formation of NH₃?
    1. 3H₂(g) + N₂(g) --> 2NH₃(g)
    2. 2NH₃(g) --> 3H₂(g) + N₂(g)
    3. 3/2H₂(g) + 1/2N₂(g) --> NH₃(g)
    4. NH₃(g) --> 3/2H₂(g) + 1/2N₂(g)
    5. 3H(g) + N(g) --> NH₃(g)

16. What is H^o for the reaction:
    4NH₃(g) + 5O₂(g) --> 4NO(g) + 6H₂O(g)

    Use the following standard enthalpies of formation:

    NH3(g)	Hof = -46.1 kJ/mol
    NO(g)	Hof = 90.3 kJ/mol
    H2O(g)	Hof = -241.8 kJ/mol

    1. 905.2 kJ
    2. 105.4 kJ
    3. -105.4 kJ
    4. -905.2 kJ
    5. -905.2 kJ/mol

17. Given that the specific heat of water is 4.184 J/g, what is the amount of heat absorbed by a 466 g sample of water that goes from 8.50^oC to 74.6^oC?
    1. -1.75 kJ
    2. 100 kJ
    3. 258 kJ
    4. -65.0 kJ
    5. 129 kJ

18. If 600 J of heat is added to a system in energy state E, and the system does 450 J of work on the surroundings, what is the energy change of the system?
    1. 150 J
    2. -150 J
    3. 1050 J
    4. -1050 J
    5. 600 J

19. Calculate the standard molar enthalpy of formation of CO₂(g) in the reaction:
    C(s) + O₂(g) --> CO₂(g)

    given the following standard enthalpy changes:

    2C(s) + O2(g) --> 2CO(g)	Ho = -221.0 kJ
    2CO(g) + O2(g) --> 2CO2(g)	Ho = -566.0 kJ

    1. -393.5 kJ
    2. +393.5 kJ
    3. +787.0 kJ
    4. -787.0 kJ
    5. +423.7 kJ

20. The addition of heat to a system will always result in a rise in its temperature.
    1. True
    2. False

21. Which property is not a state function?
    1. q
    2. H
    3. V
    4. n
    5. T

22. At constant pressure:
    1. w_P = 0
    2. H = q_P
    3. H = E
    4. q = 0
    5. q_P = 0

23. Which process is not endothermic?
    1. H₂O(s) --> H₂O(l)
    2. 2H₂O(g) --> 2H₂(g) + O₂(g)
    3. H₂O(g) --> H₂O(l)
    4. Al₂O₃ + 2Fe(l) --> 2Al + Fe₂O₃
    5. None of the above

24. Given the following bond-dissociation energies:

    H-H	435 kJ/mol
    O=O	498 kJ/mol
    O-H	464 kJ/mol

    Calculate H^o for the following reaction:

    2H₂(g) + O₂(g) --> 2H₂O(g)
    1. +5.0 kJ/mol
    2. +440 kJ/mol
    3. +448 kJ/mol
    4. -448 kJ/mol
    5. -923 kJ/mol

25. Which of the following reactions could do work of expansion on the surroundings?
    1. H₂O(g) --> H₂O(l)
    2. CH₄(g) + 2O₂(g) --> CO₂(g) + 2H₂O(g)
    3. Fe₂O₃(s) + 2Al(s) --> Al₂O₃(s) + 2Fe(s)
    4. 2CO(g) + O₂(g) --> 2CO₂(g)
    5. 2N₂O(g) --> 2N₂(g) + O₂(g)

26. Suppose a gas in a piston is expanded at constant pressure and the temperature goes down. Which of the following correctly describes the signs for the work, the heat for the system, and the energy change of the system?
    1. All are positive.
    2. Work is positive, q is negative, and E is negative.
    3. Work is positive, q is negative, and E is positive.
    4. Work is negative, q is positive, and E is positive.
    5. All are negative.

27. The heat capacity of methyl alcohol (MW = 32.05 g/mol) is 80.3 J mol^-1 K^-1. What quantity of heat will be evolved when the temperature of 2610 g of methyl alcohol falls from 22^oC to 2^oC?
    1. 7 kJ
    2. 1.3 x 10² kJ
    3. 1.5 x 10² kJ
    4. 1.7 x 10² kJ
    5. 2.0 x 10² kJ

28. In a constant-volume bomb calorimeter an unknown chemical reacted with excess oxygen to give carbon dioxide and water. The temperature of the 2.000 kg of water in the calorimeter rose from 19.84^oC to 23.84^oC. The heat capacity of the calorimeter is 2.02 kJ/^oC and the specific heat of water is 4.184 J/g^oC. The heat given off by the combustion reaction is:
    1. 41,6000 J
    2. 4.184 kJ
    3. -33.5 kJ
    4. -41.6 kJ
    5. -80.0 kJ

29. When is H_sys = E_sys?
    1. When q_v = q_p
    2. In reactions involving only liquids and solids.
    3. In reactions where the moles of gas remain constant throughout the reaction.
    4. In reactions run under a vacuum (P=0).
    5. All of the above.

30. Calculate the H^o for the following reaction:
    2ClF₃(g) + 2NH₃(g) --> N₂(g) + 6HF(g) + Cl₂(g)

    Given this information:

    ClF3(g)	Hof = -261.0 kJ/mol
    HF(g)	Hof = -271.1 kJ/mol
    NH3(g)	Hof = -46.11 kJ/mol

    1. -2241 kJ
    2. -1013 kJ
    3. -578.2 kJ
    4. 578.2 kJ
    5. not enough information

31. For an endothermic reaction, which of the following is NOT true?
    1. H^o_reaction = SUM(nH^o_products) - SUM(nH^o_reactants)
    2. H^o = 0
    3. Heat is absorbed by the system.
    4. q_surroundings is negative.
    5. An example of an endothermic process is melting ice.

32. Calculate the H^o for the reaction:
    S(s) + O₂(g) --> SO₂(g)

    Given the following data:

    S(s) + 3/2O2(g) --> SO3(g)	Ho = -395.2 kJ/mol
    2SO2(g) + O2 --> 2SO3(g)	Ho = -198.2 kJ/mol

    1. 592.2 kJ/mol
    2. -197.0 kJ/mol
    3. -296.1 kJ/mol
    4. -593.4 kJ/mol
    5. -988.6 kJ/mol

33. The amount of heat required to raise the temperature of 1.00 g of copper 1^oC is called its
    1. enthalpy
    2. specific heat
    3. molar heat
    4. heat capacity
    5. heat of formation

34. All of the following have standard enthalpy of formation values of zero at 25^oC except
    1. Cl₂(g)
    2. O₂(g)
    3. Na(g)
    4. F₂(g)
    5. N₂(g)

35. The enthalpy change for the following thermochemical equation is -53.0 kJ (note that I₂ is a solid at room temperature). The standard enthalpy of formation (kJ/mol) of HI(g) must be
    2HI(g) --> H₂(g) + I₂(s)
    1. -106 kJ/mol
    2. -53.0 kJ/mol
    3. -26.5 kJ/mol
    4. 26.5 kJ/mol
    5. 53.0 kJ/mol

36. Given the following data:

    3/2O2(g) + 2B(s) --> B2O3(s)	Ho = -1264 kJ/mol
    O3(g) + 2B(s) --> B2O3(s)	Ho = -1406 kJ/mol

    Calculate the enthalpy change for the reaction converting oxygen (O₂(g)) to ozone (O₃(g)) at 298 K and 1 atm.

    3/2O₂(g) --> O₃(g)
    1. -1406 kJ
    2. -1264 kJ
    3. -2670 kJ
    4. -142 kJ
    5. +142 kJ

37. An endothermic reaction causes the surroundings to:
    1. warm up
    2. gain heat
    3. loose heat
    4. cool down
    5. both (c) and (d)

38. Given the thermochemical equation
    2Al(s) + 3/2O₂(g) --> Al₂O₃(s) ; H^o = -95.6 kJ

    determine H^o for the following reaction

    2Al₂O₃(s) --> 4Al(s) + 3O₂(g)
    1. -95.6 kJ
    2. +95.6 kJ
    3. -47.8 kJ
    4. +47.8 kJ
    5. +191.2 kJ

39. Which one of the following refers to potential energy?
    1. Motion of gaseous molecules.
    2. Energy stored in a stretched molecular bond.
    3. Evolution of heat.
    4. Increasing the temperature of a substance.

40. Given

    N2(g) + 2O2(g) --> 2NO2(g)	H = +67.6 kJ
    2NO(g) + O2(g) --> 2NO2(g)	H = -113.2 kJ

    then the heat of the reaction for N₂(g) + O₂(g) --> 2NO(g) is:

    1. +180.8 kJ
    2. -180.8 kJ
    3. -45.6 kJ
    4. +45.8 kJ

41. Given that H = 178.1 kJ for CaCO₃(s) --> CaO(s) + CO₂(g) and the standard enthalpy of formation of CaO(s) = -635.5 kJ and for CO₂(g) = -393.5 kJ, the standard enthalpy of formation fo CaCO₃(s) is
    1. -1207.1 kJ
    2. +1207.1 kJ
    3. -320.1 kJ
    4. +850.9 kJ
    5. -850.9 kJ

42. Which one of the following statements is incorrect?
    1. Diamond and graphite are allotropes of carbon
    2. The decomposition of carbohydrates in the human body is an exothermic reaction.
    3. The formation of H₂O(g) from H₂(g) and O₂(g) is an exothermic reaction.
    4. The standard states to which enthalpies of formation refer to are 0 K and 1 atmosphere of pressure.

43. Which of the following has the largest bond enthalpy?
    1. C-C
    2. He-He
    3. H-Br
    4. C-C (triple bond)
    5. N=N

44. Limestone stalactites and stalagmites are formed in caves by the following reaction:
    Ca²⁺(aq) + 2HCO₃^-(aq) --> CaCO₃(s) + CO₂(g) + H₂O(l)

    If 1 mole of calcium carbonate forms at 298 K under 1 atmosphere pressure, the reaction performs 4.8 kJ of work pushing against the atmosphere as gaseous CO₂(g) forms. At the same time 77.9 kJ of heat is absorbed from the environment. What are the values of E and H for this reaction?

    1. E = 82.7 kJ, H = 4.8 kJ
    2. E = -82.7 kJ, H = 77.9 kJ
    3. E = 73.1 kJ, H = 77.9 kJ
    4. E = -73.1 kJ, H = 4.8 kJ
    5. E = 77.9 kJ, H = 73.1 kJ

45. Calculate H for the reaction:
    2C(s) + 3H₂(g) --> C₂H₆(g)

    given:

    (i)	2C2H6(g) + 7O2(g) --> 4CO2(g) + 6H2O(l)	H = -3120 kJ
    (ii)	C(s) + O2(g) --> CO2(g)	H = -394 kJ
    (iii)	2H2O(l) --> 2H2(g) + O2(g)	H = +572 kJ

    1. -86 kJ
    2. -1490 kJ
    3. -3206 kJ
    4. +86 kJ
    5. +1490 kJ

46. Given an initial state of a chemical system confined in a syringe with moveable piston as illustrated in the diagram. This chemical system is known to have E < 0 where the sign of E does NOT depend on the magnitude of work or heat.

    Which diagram represents a final state for this chemical system?

    

47. The vapor pressure of ethanol at 307.9 K is 100.0 torr and the heat of vaporization of ethanol is 38.6 kJ mol^-1. What is the vapor pressure of ethanol at 338.2 K?
    1. 3.8 torr
    2. 38.6 torr
    3. 386 torr
    4. 650 torr
    5. 780 torr

48. How much heat must be provided to convert exactly 1 mole of water at 20^oC to steam at 100^oC? [The specific heat of water is 7.53 x 10^-2 kJ mol^-1 K^-1 and H_vap = 40.7 kJ/mol.]
    1. 6.02 kJ
    2. 40.7 kJ
    3. 41.0 kJ
    4. 46.7 kJ
    5. 6060 kJ

49. Consider the path starting at point A and ending at point D on the adjacent phase diagram. What is the correct sequence of phases of this substance along this path? [S = solid, L = liquid, V = vapor]
    
    1. S --> L --> V --> L
    2. S --> V --> L --> S
    3. V --> S --> L --> V
    4. V --> L --> S --> V
    5. L --> S --> L --> V

50. Cold weather will surely come sometime. Your heating system is based on natural gas (mostly CH₄(g) or methane). Calculate the heat of combustion of methane. Assume that the products are CO₂(g) and H₂O(g).
    1. -74.8 kJ
    2. -890 kJ
    3. -802 kJ
    4. +802 kJ
    5. -80 kJ

51. Which of the following sequences of the H associated with the phase changes of a particular substance is correct?
    1. H_vaporization < H_sublimation < H_fusion < H_condensation
    2. H_fusion < H_condensation < H_sublimation < H_vaporization
    3. H_fusion < H_vaporization = H_condensation < H_sublimation
    4. H_condensation < H_fusion < H_vaporization < H_sublimation
    5. H_condensation < H_sublimation < H_fusion < H_vaporization

52. 1 Kcal (this is called a Calorie in nutritional tables) is equal to 4.18 kJ. It is commonly said that a person should consume 2000 Calories/day, but it is pleasant to double this amount provided that you do not get excessively fat. Taking CHM 115 you learned that the heat of fusion of solid H₂O is 6.02 kJ/mole. How much ice would you have to melt to compensate for an additional 2000 Kcal?
    1. 332.2 g
    2. 1389 g
    3. 5980 g
    4. 3.010 kg
    5. 25.00 kg

53. Two gaseous pollutants in auto exhaust are CO and NO. An environmental chemist is studying ways to convert them to less harmful gases through a reaction represented by the following equation:
    CO(g) + NO(g) --> CO₂(g) + 1/2N₂(g) ; H = ?

    Calculate the H for the reaction using the following information:

    Equation A:	CO(g) + 1/2O2(g) --> CO2(g)	HA = -283.0 kJ
    Equation B:	N2(g) + O2(g) --> 2NO(g)	HB = 180.6 kJ

    1. -102.4 kJ
    2. -322.1 kJ
    3. -373.3 kJ
    4. -400.0 kJ
    5. -463.6 kJ

54. If 125 g of copper forms a welded layer on the bottom of a skillet, how much heat is needed to raise the temperature of the copper layer from 25^oC to 300^oC? The specific heat of Cu = 0.387 J g^-1K^-1.
    1. 13 kJ
    2. 6.0 kJ
    3. 3.0 kJ
    4. 0.60 kJ
    5. 0.13 kJ

55. A balloon is heated by adding 580 J of heat. It expands doing 320 J of work against the atmosphere. What is the change in internal energy?
    1. -900 J
    2. -260 J
    3. 0 J
    4. +260 J
    5. +900 J

56. The specific heat of water is 4.18 J g^-1 K^-1 and that of stainless steel is 0.51 J g^-1 K^-1. Calculate the heat that must be supplied to a 750.0 g stainless steel vessel containing 800.0 g of water to raise its temperature from 20.0^oC to the boiling point of water.
    1. 2.98 kJ
    2. 6.98 kJ
    3. 29.8 kJ
    4. 69.8 kJ
    5. 298 kJ

57. For the reaction:
    NH₄NO₃(s) --> N₂(g) + 2H₂O(g) + 1/2O₂(g)

    H^o = -1.50 kJ/g NH₄NO₃ (molecular mass = 80.05 amu). If 0.105 g NH₄NO₃ decompose in a bomb calorimeter with a heat capacity of 5.510 J/^oC initially at 21.00^oC, the final temperature of the calorimeter and its contents will be numerically (in K):

    1. 223
    2. 281
    3. 323
    4. 381
    5. none of the above

58. Consider the following reaction:
    2N₂(g) + O₂(g) --> 2N₂O(g) ; H = +163.2 kJ

    What amount of heat is involved when 25.0 g of N₂O decompose?

    1. +163 kJ
    2. +111 kJ
    3. -104 kJ
    4. -92.7 kJ
    5. -46.4 kJ

59. Using the information below, calculate the standard enthalpy of formation of Be(OH)₂.

    (i)	2Be(s) + O2(g) --> 2BeO(s)	Ho = -1216.8 kJ
    (ii)	Be(OH)2(s) --> BeO(s) + H2O(l)	Ho = +11.5 kJ
    (iii)	2H2(g) + O2(g) --> 2H2O(l)	Ho = -571.8 kJ

    1. -1800.1 kJ
    2. -882.8 kJ
    3. -905.8 kJ
    4. -1777.1 kJ
    5. +1106.6 kJ

60. Calculate the molar enthalpy of combustion of propylene, C₃H₆(g), when it reacts with O₂(g) to give CO₂(g) and H₂O(l). [H_f^o (C₃H₆(g)) = +20.4 kJ/mol]
    1. +699.7 kJ
    2. -658.6 kJ
    3. -1926.3 kJ
    4. -2017.5 kJ
    5. -2058.3 kJ

61. In theory, B₅H₉ should be an excellent rocket fuel because of the enormous amount of energy released when this compound burns:
    2B₅H₉(g) + 12O₂(g) --> 5B₂O₃(s) + 9H₂O(g)

    What is the molar heat of reaction for the combustion of B₅H₉ if the reaction between 0.100 g of B₅H₉ and excess oxygen in a bomb calorimeter raises the temperature of the 852 g of water surrounding the calorimeter by 1.57^oC? [At wts: B = 10.81 amu; H = 1.008 amu; O = 16.00 amu; the heat capacity of water is 4.184 J / g^oC]

    1. 5.60 x 10³ J/mol
    2. 4.46 x 10³ kJ/mol
    3. 5.59 kJ/mol
    4. 3.54 x 10³ kJ/mol
    5. 9.14 x 10² kJ/mol

62. The molar heat capacity for NaCl is 50.50 J mol^-1 K^-1. What is the specific heat?
    1. 0.4490 J g^-1 K^-1
    2. 0.5050 J g^-1 K^-1
    3. 0.8640 J g^-1 K^-1
    4. 4.184 J g^-1 K^-1
    5. 50.50 J g^-1 K^-1

63. When work is done by a system at constant temperature, which of the following is true?
    1. q + w = 0
    2. w is positive
    3. q is negative
    4. E_univ is positive
    5. w is negative

64. Given the following bond energies, the heat of formation of HCl is:

    H-H	436 kJ
    Cl-Cl	242 kJ
    H-Cl	432 kJ

    1. 186 kJ/mol
    2. -186 kJ/mol
    3. 1,110 kJ/mol
    4. 93 kJ/mol
    5. -93 kJ/mol

65. Given the following data

    N2(g) + O2(g) --> 2NO(g)	H = 180.8 kJ
    1/2N2(g) + O2(g) --> NO2(g)	H = 33.9 kJ

    calculate the enthalpy change for the following reaction

    NO(g) + 1/2O₂(g) --> NO₂(g)
    1. 214.7 kJ
    2. 146.9 kJ
    3. -56.5 kJ
    4. 56.5 kJ
    5. -146.9 kJ

66. Calculate the enthalpy change, H^o, for the combustion of benzene, C₆H₆, given the following
    C₆H₆(l) + 15/2O₂(g) --> 6CO₂(g) + 3H₂O(l)

    H_f^o values in kJ/mol are as follows:

    C₆H₆(l) = 49.0; CO₂(g) = -393.5; H₂O(l) = -285.8
    1. -3169.4 kJ
    2. 3267.4 kJ
    3. -728.3 kJ
    4. 3169.4 kJ
    5. -3267.4 kJ

67. Calculate the amount of heat required to change the temperature of a 150.0 g block of ice from -25.0^oC to 60.0^oC.
    1. 45.5 kJ
    2. 51.4 kJ
    3. 53.3 kJ
    4. 95.5 kJ
    5. 103 kJ

68. Which one of the following refers to kinetic energy?
    1. energy stored by stretching a spring
    2. electrostatic attraction between cations and anions in an ionic solid
    3. increasing the temperature of a chemical system
    4. a skier at the top of a mountain
    Use the following information, at 25^oC and 1 atm, to answer the next three (3) questions.

    C(graphite) + O2(g) --> CO2(g)	Ho = -393.5 kJ
    H2(g) + 1/2O2(g) --> H2O(l)	Ho = -285.8 kJ
    2C2H6(g) + 7O2(g) --> 4CO2(g) + 6H2O(l)	Ho = -3119.6 kJ

69. The H_f^o value for water(l) is:
    1. 393.5 kJ
    2. 571.6 kJ
    3. -571.6 kJ
    4. -285.8 kJ

70. The H_f^o value for C₂H₆(g) refers to:
    1. 2C(graphite) + 3H₂(g) --> C₂H₆(g)
    2. 2C(graphite) + 3H₂(g) --> C₂H₆(l)
    3. C(graphite) + 3/2H₂(g) --> 1/2C₂H₆(g)
    4. C₂H₆(g) --> 2C(graphite) + 3H₂(g)

71. The numerical H_f^o value for C₂H₆(g) (in kJ) is:
    1. 84.6
    2. 169.2
    3. -84.6
    4. -169.2
    5. 47.3

Answers

1. C
2. B
3. E
4. D
5. A
6. E
7. A
8. D
9. B
10. C
11. C
12. D
13. C
14. D
15. C
16. D
17. E
18. A
19. A
20. B
21. A
22. B
23. C
24. D
25. E
26. E
27. B
28. D
29. E
30. B
31. B
32. C
33. B
34. C
35. D
36. E
37. E
38. E
39. B
40. A
41. A
42. D
43. D
44. C
45. A
46. E
47. C
48. D
49. B
50. C
51. D
52. E
53. C
54. A
55. D
56. E
57. C
58. E
59. C
60. E
61. D
62. C
63. E
64. E
65. C
66. E
67. D
68. C
69. D
70. A
71. C