Chemistry 4th Edition by Julia Burdge - Test Bank

Chemistry 4th Edition by Julia Burdge – Test Bank

 

Instant Download – Complete Test Bank With Answers

 

 

Sample Questions Are Posted Below

 

Chapter 05

Thermochemistry

 

1. If two solutions are mixed together in a container and the container “feels hot”, then
2. the reaction is endothermic.
3. B. the reaction is exothermic.
4. the energy of the universe is increased.
5. the energy of both the system and the surroundings is decreased.
6. the energy of the system is increased.

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

2. For the reaction: 2A + B₂ → 2AB ΔH = +50.0 kJ.
3. A. The reaction is endothermic.
4. Heat is released to the surroundings.
5. The standard enthalpy of formation for AB is 50.0 kJ.
6. The bond energy for each A–B bond is 50.0 kJ.
7. The molecule AB contains less energy than A or B₂.

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

3. An endothermic reaction causes the surroundings to
4. warm up.
5. become acidic.
6. condense.
7. D. decrease in temperature.
8. release CO₂.

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

4. An exothermic reaction causes the surroundings to
5. A. warm up.
6. become acidic.
7. expand.
8. decrease its temperature.
9. release CO₂.

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

5. How many calories are in 854.3 J? (1 cal = 4.184 J)
6. 4.897 × 10^–3 cal
7. B. 2 cal
8. 1.171 ×10^–3 cal
9. 0.2390 cal
10. 3574 cal

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

6. How many joules are in 1.20 ×10³ calories? (1 cal = 4.184 J)
7. 8.33 × 10^–4 J
8. 3.49 × 10^–3 J
9. 2.39 × 10^–1 J
10. 2.86 × 10² J
11. E. 02 × 10³ J

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

7. Which type of system may transfer energy, but not mass, to the surroundings?
8. mass transfer system
9. isolated system
10. C. closed system
11. nonenergy system
12. open system

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

8. Which of these is not a state function?
9. volume
10. temperature
11. pressure
12. D. heat
13. energy

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

9. What law states that energy can be converted from one form to another, but cannot be created or destroyed?
10. universal law
11. B. first law of thermodynamics
12. law of mass conservation
13. law of conservation of energy
14. law of constant energy

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Topic: Thermochemistry

 

 

 

10. When heat is absorbed by the system and work is done by the system on the surroundings then
11. q is negative and w is positive.
12. both q and w are positive.
13. both q and w are negative.
14. D. q is positive and w is negative.
15. both q and W are zero.

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

11. What is the change in internal energy in joules for a system that releases 154 J of heat and does 125 J of work on its surroundings?
12. –29 J
13. 279 J
14. 29 J
15. 1.23 J
16. E. –279 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

12. Complete the sentence: When heat is transferred to the system, the process is said to be ____________, and the sign of q is __________.
13. exothermic, positive
14. exothermic, negative
15. C. endothermic, positive
16. endothermic, negative
17. forbidden, indeterminate

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

13. A system that does no work but which transfers heat to the surroundings has
14. q < 0, ΔU > 0.
15. B. q < 0, ΔU < 0.
16. q > 0, ΔU > 0.
17. q > 0, ΔU < 0.
18. E. q < 0, ΔU = 0.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

14. A system that does no work but which receives heat from the surroundings has
15. q < 0, ΔU > 0.
16. q > 0, ΔU < 0.
17. C. q = Δ
18. q = –ΔU.
19. w = ΔU.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

15. A system which does work on the surroundings with no heat change (i.e., q = 0) has
16. w < 0, ΔU = 0.
17. W > 0, ΔU > 0.
18. W > 0, ΔU < 0.
19. W < 0, ΔU > 0.
20. E. W < 0, ΔU < 0.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

16. A system which does work on the surroundings with no heat change (i.e., q = 0) has
17. A. W = Δ
18. W = –ΔU.
19. W > 0, ΔU < 0.
20. W < 0, ΔU > 0.
21. W > ΔU.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

17. A system contracts from an initial volume of 15.0 L to a final volume of 10.0 L under a constant external pressure of 0.80 atm. What is W? (1 L·atm = 101.3 J)
18. –4.0 J
19. +4.0 J
20. –4.1 ×10² J
21. D. +4.1 ×10² J
22. +81 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Subtopic: Units of Energy

Topic: Thermochemistry

 

18. An ideal gas (the system) is contained in a flexible balloon at a pressure of 1 atm and is initially at a temperature of 20.°C. The surrounding air is at the same pressure, but its temperature is 25°C. When the system has equilibrated with its surroundings, both system and surroundings are at 25°C and 1 atm. In changing from the initial to the final state, which one of the following relationships regarding the system is correct?
19. ΔU < 0
20. ΔU = 0
21. ΔH = 0
22. W > 0
23. E. q > 0

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

19. Which relationship is always correct?
20. potential energy + kinetic energy = constant
21. Δ = q + W
22. ΔU = ΔH – PΔV
23. D. H = U + PV
24. ΔH = q V

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

20. A system expands from a volume of 1.00 L to 2.00 L against a constant external pressure of 1.00 atm. What is the work (W) done by the system? (1 L·atm = 101.3 J)
21. 1.00 J
22. 2.00 J
23. C. 01 × 10² J
24. 1.01 × 10⁵ J
25. 3.00 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Subtopic: Units of Energy

Topic: Thermochemistry

 

21. For a particular process, 28 kJ of heat is absorbed and 15 kJ of work is done on the surroundings. What is ΔU?
22. ΔU = +43 kJ
23. ΔU = –43 kJ
24. ΔU = –13 kJ
25. D. ΔU = +13 kJ
26. ΔU = +28 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

22. A system delivers 1275 J of heat while the surroundings perform 854 J of work on it. What is ΔU of the system?
23. –2129 J
24. B. –421 J
25. +421 J
26. +2129 J
27. –1275 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

23. A system delivers 222 J of heat to the surroundings while delivering 645 J of work. What is the change in the internal energy, ΔU, of the system?
24. –423 J
25. +423 J
26. C. –867 J
27. +867 J
28. –222 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

24. A system receives 575 J of heat and delivers 424 J of work. What is the change in the internal energy, ΔU, of the system?
25. –150. J
26. B. J
27. –1000. J
28. 1000. J
29. 575 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

25. A system initially has an internal energy U of 504 J. It undergoes a process during which it releases 111 J of heat energy to the surroundings, and does work of 222 J. What is the final energy of the system, in J?
26. A. 171 J
27. 393 J
28. 504 J
29. 615 J
30. 837 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

26. A system absorbs 21.6 kJ of heat while performing 6.9 kJ of work on the surroundings. If the initial internal energy, U, is 61.2 kJ, what is the final value of U?
27. 32.7 kJ
28. 46.5 kJ
29. 61.2 kJ
30. D. 9 kJ
31. 89.7 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

27. In which process is ΔH = ΔU?
28. Two moles of ammonia gas are cooled from 325°C to 300°C at a constant pressure of 1.2 atm.
29. One gram of water is vaporized at 100°C and 1 atm.
30. C. Two moles of hydrogen iodide gas react to form hydrogen gas and iodine gas in a 40-L container.
31. Solid calcium carbonate is heated to form solid calcium oxide and carbon dioxide gas in a container with variable volume.
32. One mole of solid carbon dioxide sublimes to the gas phase.

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

28. What is the equation for the formation reaction for gaseous hydrazine, N₂H₄, at 25ºC and 1 atm pressure?
29. 2N₂H₄(g) → 2NH₃(g) + H₂(g)
30. 2NH₃(g) + H₂(g) → N₂H₄(g)
31. N₂(g) + 2H₂O(g) → N₂H₄(g) + O₂(g)
32. D. N₂(g) +2H₂(g) → N₂H₄(g)
33. 2NO₂(g) + 6H₂(g) → N₂H₄(g) + 4H₂O(g)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Topic: Thermochemistry

 

29. For which reaction is ΔH approximately (or exactly) equal to ΔU?
30. A. H₂(g) + Br₂(g) → 2HBr(g)
31. H₂O(l) → H₂O(g)
32. CaCO₃(s) → CaO(s) + CO₂(g)
33. 2H(g) + O(g) → H₂O(l)
34. CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

30. In which reaction would you expect ΔH to be substantially greater than ΔU (i.e., ΔH > ΔU)?
31. H₂(g) + Br₂(g) → 2HBr(g)
32. B. CO₂(s) → CO₂(g)
33. C₂H₂(g) + H₂(g) → C₂H₄(g)
34. H₂O(s) → H₂O(l)
35. HCl(aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

31. The dissolution of barium hydroxide in water is an exothermic process. Which statement is correct?
32. The enthalpy of solid barium hydroxide plus pure water is less than that of the solution, at the same temperature.
33. B. The enthalpy of solid barium hydroxide plus pure water is greater than that of the solution, at the same temperature.
34. The enthalpy of solid barium hydroxide plus pure water is the same as that of the solution, at the same temperature.
35. The temperature of the solution is lower than of the barium hydroxide and water before mixing.
36. When barium hydroxide dissolves in water, the system does work on the surroundings.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

32. Two solutions (the system), each with a volume of 25.0 mL at 25.0°C, are mixed in a beaker. A reaction occurs between them, and the temperature rises to 35.0°C. After the products have equilibrated with the surroundings, the temperature is again 25.0°C and the total volume is 50.0 mL. No gases are involved in the reaction. Which relationship concerning the change from initial to final states (both at 25.0°C) is correct?
33. ΔU = 0
34. ΔH = 0
35. ΔU > 0
36. q = 0
37. E. W = 0

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

33. A Snickers® candy bar contains 280 Calories, of which the fat content accounts for 120 Calories. What is the energy of the fat content, in kJ? (1 cal = 4.184 J)
34. 5.0 × 10^–1 kJ
35. 1.2 kJ
36. C. 0 × 10² kJ
37. 1.2 × 10³ kJ
38. 1.6 × 10³ kJ

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

 

 

34. Your favorite candy bar, Gummy Beakers, contains 1.2 × 10⁶ J of energy while your favorite soft drink, Bolt, contains 6.7 × 10⁵ J. If you eat two packs of Gummy Beakers a day and drink 3 cans of Bolt, what percent of your 2000 Calorie daily food intake is left for broccoli, beans, beef, etc.? (1 cal = 4.184 J)
35. 53%
36. B. 47%
37. 27%
38. 11%
39. 0%

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

35. Natural gas, or methane, is an important fuel. Combustion of one mole of methane releases 802.3 kJ of energy. How much energy does that represent in kcal? (1 cal = 4.184 J)
36. 1.92 × 10^–1 kcal
37. B. 92 × 10² kcal
38. 3.36 × 10³ kcal
39. 1.92 × 10⁵ kcal
40. 3.36 × 10⁶ kcal

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

36. Which is not a state function?
37. internal energy
38. volume
39. C. work
40. pressure
41. enthalpy

 

Blooms: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

37. The specific heat (capacity) is
38. A. amount of energy needed to change 1 g of a substance by 1°C.
39. amount of energy needed to change 1 mol of a substance by 1°C.
40. amount of energy required to melt 1 g of substance.
41. amount of substance that is heated by 1°C.
42. the temperature increase, in K, associated with heating 1 g of a substance for 1 minute.

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

38. What is q if 28.6 g of water is heated from 22.0°C to 78.3°C? The specific heat of water is 4.184 J/g·°C.
39. 2.60 J
40. 2.63 kJ
41. C. 74 kJ
42. 9.37 kJ
43. 3.94×10⁴ kJ

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

39. If, as a pioneer, you wished to warm your room by taking an object heated on top of a pot-bellied stove to it, which of the following 15-pound objects, each heated to 100°C, would be the best choice? The specific heat capacity (in J/g·°C) for each substance is given in parentheses. Iron (0.450), copper (0.387), granite (0.79), gold (0.129), water (4.184).
40. iron
41. copper
42. granite
43. gold
44. E. H₂O

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

40. Ethylene glycol, used as a coolant in automotive engines, has a specific heat capacity of 2.42

J/g°C. Calculate q when 3.65 kg of ethylene glycol is cooled from 132°C to 85°C.

1. –1900 kJ
2. B. –420 kJ
3. –99 kJ
4. –0.42 kJ
5. –4.2 × 10^–6 kJ

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

41. If 75.4 J of energy is absorbed by 0.25 mol of CCl₄ at constant pressure, what is the change in temperature? The specific heat of CCl4 is 0.861 J/g·°C.
42. 17.8°C
43. 21.9°C
44. C. 3°C
45. 9.1°C
46. 44.6°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

42. A 275-g sample of nickel at l00.0°C is placed in 100.0 g of water at 22.0°C. What is the final temperature of the water? Assume no heat transfer with the surroundings. The specific heat of nickel is 0.444 J/g·°C and the specific heat of water is 4.184 J/g·°C.
43. A. 6°C
44. 40.8°C
45. 61.0°C
46. 79.2°C
47. 82.4°C

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

43. Benzene is a starting material in the synthesis of nylon fibers and polystyrene (styrofoam). Its specific heat capacity is 1.74 J/g·°C. If 16.7 kJ of energy is absorbed by a 225-g sample of benzene at 20.0°C, what is its final temperature?
44. –22.7°C
45. 37.7°C
46. 42.7°C
47. D. 7°C
48. 80.1°C

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

44. When Karl Kaveman adds chilled grog to his new granite mug, he removes 10.9 kJ of energy from the mug. If it has a mass of 625 g and was at 25°C, what is its new temperature? Specific heat capacity of granite = 0.79 J/g·°C.
45. A. 3°C
46. 14°C
47. 22°C
48. 47°C
49. None of these choices is correct.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

45. A 307-g sample of an unknown mineral was heated to 98.7°C and placed into a calorimeter containing 72.4 g of water at 23.6°C. The heat capacity of the calorimeter was 15.7 J/°C. The final temperature in the calorimeter was 32.4°C. What is the specific heat capacity of the mineral?
46. 0.124 J/g·°C
47. 0.131 J/g·°C
48. C. 138 J/g·°C
49. 0.145 J/g·°C
50. None of these choices is correct.

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

46. A piece of copper metal is initially at 100.0°C. It is dropped into a coffee cup calorimeter containing 50.0 g of water at a temperature of 20.0°C. After stirring, the final temperature of both copper and water is 25.0°C. Assuming no heat losses, and that the specific heat (capacity) of water is 4.18 J/g·°C, what is the heat capacity of the copper in J/°C?
47. 2.79 J/°C
48. 3.33 J/°C
49. C. 9 J/°C
50. 209 J/°C
51. None of these choices is correct.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

47. A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of 0.500 M HCl at 25.0°C is added to 50.0 mL of 0.500 M NaOH at 25.0°C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2°C. What is the heat of reaction per mole of acid? Assume the mixture has a specific heat capacity of 4.18 J/g·°C and that the densities of the reactant solutions are both 1.00 g/mL.
48. 670 J
49. 1300 J
50. 27 kJ
51. D. 54 kJ
52. > 100 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Calculating Amounts of Reactant and Product (including solutions)

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Subtopic: Types of Chemical Reactions (Acid-Base, REDOX, Displacement, etc.)

Subtopic: Units of Concentration

Topic: Aqueous Solutions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

48. How much heat is required to raise the temperature of 22.8 g of copper from 20.0°C to 875.0°C?

The specific heat of copper is 0.385 J/g·°C.

14. 14.4 J
15. 176 J
16. C. 51 kJ
17. 7.68 kJ
18. 9.90 kJ

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

49. How much heat is required to raise the temperature of 12.0 g of water from 15.4°C to 93.0°C? The specific heat of water is 4.184 J/g·°C.
50. 223 J
51. 773 J
52. 503 J
53. 4.67 ×10³ J
54. E. 90 ×10³ J

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

50. How much heat is required to raise the temperature of 1500 g of water from 25°C to 52°C? The specific heat of water is 4.184 J/g·°C.
51. 1500 kJ
52. B. 170 kJ
53. 6.3 kJ
54. 41 J
55. 41 kJ

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

51. What is the change in temperature if a 25.0-g block of aluminum absorbs 10.0 kJ of heat? The specific heat of aluminum is 0.900 J/g·°C.
52. 0.44°C
53. 22.5°C
54. 225°C
55. 360°C
56. E. 444°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

52. If 325 g of water at 4.2°C absorbs 12.28 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/g·°C.
53. 4.21°C
54. 4.8°C
55. 9.0°C
56. D. 2°C
57. 2938°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

53. A glass containing 200.0 g of H₂O at 20.0°C was placed in a refrigerator. The water loses 11.7 kJ as it cools to a constant temperature. What is its new temperature? The specific heat of water is 4.184 J/g·°C.
54. 0.0°C
55. 4.0°C
56. C. 0°C
57. 14.0°C
58. 34.0°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

54. A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?
55. A. 385 J/g·°C
56. 1.83 × 10⁴ J/g·°C
57. 2.60 J/g·°C
58. 1.32 J/g·°C
59. 24.5 J/g·°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: Molar Mass

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

55. The specific heat of gold is 0.129 J/g·°C. What is the molar heat capacity of gold?
56. 0.0394 J/mol·°C
57. 0.129 J/mol·°C
58. C. 4 J/mol·°C
59. 39.4 kJ/mol·°C
60. 197 J/mol·°C

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: automatic

Subtopic: Molar Mass

Subtopic: System/Surroundings and Heat/Work

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

56. Suppose a 50-g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50-g block of iron (specific heat = 0.4494 J/g·°C) at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks
57. will be higher than 50°C.
58. B. will be lower than 50°C.
59. will be exactly 50°C.
60. is unrelated to the composition of the blocks.
61. cannot be predicted.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

57. When 0.7521 g of benzoic acid was burned in a calorimeter containing 1000. g of water, a temperature rise of 3.60°C was observed. What is the heat capacity of the bomb calorimeter, excluding the water? The heat of combustion of benzoic acid is –26.42 kJ/g.
58. 15.9 kJ/°C
59. 4.2 kJ/°C
60. 5.5 kJ/°C
61. D. 3 kJ/°C
62. 752 kJ/°C

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

58. A 1.00-g sample of octane (C₈H₁₈) is burned in a bomb calorimeter that has a heat capacity of 5.80 kJ/°C. The temperature of the calorimeter rises from 25.00°C to 33.20°C. What is ΔU per mole for the combustion of octane?
59. –47.6 kJ/mol
60. –416 kJ/mol
61. –707 kJ/mol
62. D. –5.43 ×10³ kJ/mol
63. –1.86 ×10⁵ kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: Molar Mass

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: System/Surroundings and Heat/Work

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

59. Naphthalene combustion may be used to calibrate the heat capacity of a bomb calorimeter. The heat of combustion of naphthalene is –40.1 kJ/g. When 0.8210 g of naphthalene was burned in a bomb calorimeter containing 1.000 kg of water, a temperature rise of 4.21°C was observed. What is the heat capacity of the bomb calorimeter excluding the water?
60. 32.9 kJ/°C
61. 7.8 kJ/°C
62. C. 64 kJ/°C
63. 1.76 kJ/°C
64. 15.3 kJ/°C

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

60. The heat of solution of ammonium chloride is 15.2 kJ/mol. If a 6.134-g sample of NH₄Cl is added to 65.0 mL of water in a calorimeter at 24.5°C, what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 365 J/°C.
61. 27.1°C
62. 18.6°C
63. 19.7°C
64. D. 8°C
65. 30.4°C

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

61. The heat of solution of ammonium nitrate is 26.2 kJ/mol. If a 5.368 g sample of NH₄NO₃ is added to 40.0 mL of water in a calorimeter at 23.5°C, what is the final temperature of the solution? The specific heat of water is 4.18 J/g·°C and the heat capacity of the calorimeter is 0.650 kJ/°C.
62. 14.3°C
63. 20.8°C
64. –7.7°C
65. 25.6°C
66. E. 4°C

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

62. When 0.560 g of Na(s) reacts with excess F₂(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH°_f) of NaF(s)?
63. 567 kJ/mol
64. –24.8 kJ/mol
65. –7.8 kJ/mol
66. 24.8 kJ/mol
67. E. –567 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Molar Mass

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: System/Surroundings and Heat/Work

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

63. Based on the following thermochemical equations, what is the heat of vaporization of titanium(IV) chloride?

Ti(s) + 2 Cl2(g) → TiCl4(l)	ΔH = –804.2 kJ/mol
TiCl4(g) → 2 Cl2(g) + Ti(s)	ΔH = 763.2 kJ/mol

41. A. +41.0 kJ/mol
42. –1567.4 kJ/mol
43. 1567 kJ/mol
44. –41.0 kJ/mol
45. –763.7 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

64. Octane (C₈H₁₈) undergoes combustion according to the following thermochemical equation.

2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l)   ΔH°rxn = –1.0940 × 104kJ/mol
What is the standard enthalpy of formation of liquid octane?
ΔH°f(CO2(g)) = –393.5 kJ/mol and ΔH°f(H2O(l)) = –285.8 kJ/mol

1. A. –250 kJ/mol
2. –10,940. kJ/mol
3. –2188 kJ/mol
4. –495 kJ/mol
5. 495 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Thermochemistry

 

65. Glycine, C₂H₅O₂N, is important for biological energy. The combustion reaction of glycine is described by the following thermochemical equation.

4C₂H₅O₂N(s) + 9O₂(g) → 8CO₂(g) + 10H₂O(l) + 2N₂(g) ΔH°_rxn = –3896 kJ/mol

What is the standard enthalpy of formation of solid glycine?

51. –51.90 kJ/mol
52. B. –527.5 kJ/mol
53. –974.0 kJ/mol
54. –1502 kJ/mol
55. –2476 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

66. Which of the following has a standard enthalpy of formation value (ΔH°_f) of zero at 298 K?
67. H₂O(g)
68. O(g)
69. H₂O(l)
70. D. O₂(g)
71. O₃(g)

 

Blooms: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

67. Styrene, C₈H₈, is one of the substances used in the production of synthetic rubber. When styrene burns in oxygen to form carbon dioxide and liquid water under standard-state conditions at 25°C, 42.15 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C.

ΔH°_f(CO₂(g)) = –393.5 kJ/mol, ΔH°_f(H₂O(l)) = –285.8 kJ/mol

1. –4390 kJ/mol
2. –1044 kJ/mol
3. –8681 kJ/mol
4. D. +99 kJ/mol
5. +637 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Molar Mass

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

68. What is ΔH°_rxn for the following reaction?

2H₂O₂(l) → 2H₂O(l) + O₂(g)

ΔH°_f(H₂O(l)) = –285.8 kJ/mol, ΔH°_f(H₂O₂(l)) = –187.6 kJ/mol

196. A. –196.4 kJ/mol
197. 98.2 kJ/mol
198. –98.2 kJ/mol
199. –473.4 kJ/mol
200. –946.8 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

69. What is ΔH°_rxn for the reaction 2Al₂O₃(s) → 4Al(s) + 3O₂(g)?

ΔH°_f(Al₂O₃(s)) = –1670 kJ/mol

1. A. 3340 kJ/mol
2. 1670 kJ/mol
3. –3340 kJ/mol
4. –1670 kJ/mol
5. –835 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

70. Which equation has a ΔH_rxn that is not equal to ΔH^o_f of the product?
71. O₂(g) + H₂(g) → H₂O₂(g)
72. ½O₂(g) + H₂(g) → H₂O(g)
73. H₂(g) + ½O₂(g) + → H₂O(l)
74. D. NO(g) + ½O₂(g) → NO₂(l)
75. ½H₂(g) + ½Cl₂(g) → HCl(g)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

71. Which equation has a ΔH_rxn that is not equal to ΔH^o_f of the product?

rev: 04_28_2015_QC_CS-14747

1. F₂(g) + ½O₂(g) → F₂O(g)
2. B. O₂(g) + 2H₂(g) → 2 H₂O(g)
3. H₂(g) + ½O₂(g) + → H₂O(l)
4. Ti(s) + 2Cl₂(g) → TiCl₄(l)
5. ½H₂(g) + ½ Cl₂(g) → HCl(g)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

72. Which represents an enthalpy change at 25 °C and 1 atm that is equal to ΔH^o_f for H₂O(l)?
73. O₂(g) + 2H₂(g) → 2H₂O(l)
74. ½O₂(g) + H (g) → H₂O(g)
75. C. H₂(g) + ½O₂(g) + → H₂O(l)
76. 2H₂O(l) → O₂(g) + 2H₂(g)
77. H₂O(l) → ½O₂(g) + H₂(g)

 

Blooms: 5. Evaluate

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

73. What is the standard enthalpy of formation of liquid methanol, CH₃OH(l)?

C(graphite) + O2(g) → CO2(g)	ΔH°rxn = –393.5 kJ/mol
H2(g) + ½O2→ H2O(l)	ΔH°rxn = –285.8 kJ/mol
CH3OH(l) + 3/2O2(g) → CO2(g) + 2H2O(l)	ΔH°rxn = –726.4 kJ/mol

1691. –1691.5 kJ/mol
1692. B. –238.7 kJ/mol
1693. 1691.5 kJ/mol
1694. 47.1 kJ/mol
1695. –47.1 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

74. What is ΔH°_rxn for the following reaction?

C6H6(l) + 15/2 O2(g) → 6CO2(g) + 3H2O(l)
6C(graphite) + 3H2(g) → C6H6(l)	ΔH°rxn = +49.0 kJ/mol
C(graphite) + O2(g) → CO2(g)	ΔH°rxn = –393.5 kJ/mol
H2(g) + ½O2(g) → H2O(l)	ΔH°rxn = –285.8 kJ/mol

630. –630.3 kJ/mol
631. –2597.8 kJ/mol
632. –3169.4kJ/mol
633. D. –3267.4 kJ/mol
634. 630.3 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

75. What is ΔH°_rxn for the following reaction?

2C8H18(l) + 17O2(g) → 16CO(g) + 18H2O(l)
2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l)	ΔH°rxn = –11020. kJ/mol
2CO(g) + O2(g) → 2CO2(g)	ΔH°rxn = –566.0 kJ/mol

11020. –11020. kJ/mol
11021. +6492 kJ/mol
11022. –1964 kJ/mol
11023. D. –6492 kJ/mol
11024. –11586 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

76. Calculate the standard enthalpy change for the reaction

2C8H18(l) + 21O2(g) → 8CO(g) + 8CO2(g) + 18H2O(l). Given:
2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l)	ΔH° = –11,020. kJ/mol
2CO(g) + O2(g) → 2CO2(g)	ΔH° =   –566.0 kJ/mol

1. 1.0454 × 10⁴ kJ/mol
2. B. –8756 kJ/mol
3. 1.1586 × 10⁴ kJ/mol
4. –6492 kJ/mol
5. –1.0454 × 10⁴ kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

77. What is the standard enthalpy change for the decomposition of one mole of SO₃?

2SO₂ + O₂→ 2SO₃ ΔH°_rxn = –198 kJ/mol

1. 198 kJ/mol
2. –99.0 kJ/mol
3. C. 0 kJ/mol
4. 396 kJ/mol
5. –396 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

78. Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l). What is ΔH° for the combustion of 1 mol of B₅H₉(s)?

Substance                                    ΔH°_f (kJ/mol)

B₂O₃(s)                                        –1273.5

B₅H₉(s)                                        +73.2

H₂O(l)                                          –285.8

 

1486. -1486.1 kJ
1487. -1632.5 kJ
1488. -4396.7 kJ
1489. D. -4652.85 kJ
1490. -9086.1 kJ

Difficulty: Hard

Gradable: automatic

 

79. Given that CaO(s) + H₂O(l) → Ca(OH)₂(s), ΔH°_rxn = –64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat?
80. 6.92 g
81. 56.1 g
82. C. 454 g
83. 606 g
84. 3.40 × 10⁴ g

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

80. The combustion of pentane produces heat according to the following thermochemical equation.

C₅H₁₂(l) + 😯₂(g) → 5CO₂(g) + 6H₂O(l)                ΔH°_rxn = –3510 kJ/mol

How many grams of CO₂ is produced per 2.50 × 10³ kJ of heat released?

6. 6.27 g
7. 31.3 g
8. 61.8 g
9. D. 157 g
10. 220 g

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

81. How much heat is evolved if 0.600 kg of SO₂ is burned in excess oxygen?

2SO₂(g) + O₂(g) → 2SO₃(g)                    ΔH°_rxn = –198 kJ/mol

5. 5.46 × 10–2 kJ
6. B. 927 kJ
7. 1.85 × 10³ kJ
8. 59,400 kJ
9. 3.71 × 10³ kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

82. Pentaborane B₅H₉(s) burns vigorously in O₂ to give B₂O₃(s) and H₂O(l). What is ΔH° for the combustion of 1 mol of B₅H₉(s)?

Substance                ΔH°_f(kJ/mol)

B₂O₃(s)                    –1273.5

B₅H₉(s)                    +73.2

H₂O(l)                     –285.8

1. -1.5 × 10³ kJ
2. -1.6× 10³ kJ
3. -4.4 × 10³ kJ
4. D. -4.7× 10³ kJ
5. -9.0× 10³ kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

 

 

83. How much heat is released if 35.0 g of ethanol (C₂H₅OH) burns in excess oxygen?

C₂H₅OH(l) + 3O₂(g) → 2 CO₂(g) + 3 H₂O(l) ΔH°_rxn = –1367 kJ/mol

1. 1797 kJ
2. 1367 kJ
3. 9.61 × 10^–4 kJ
4. 4.78 × 10⁴ kJ
5. E. 1040 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

84. How much heat is released if 7.15 g CaO(s) is added to 152 g of H₂O(l)?

CaO(s) + H₂O(l) → Ca(OH)₂(s) ΔH°_rxn = –64.8 kJ/mol

7. 7.68 kJ
8. B. 26 kJ
9. 508 kJ
10. 547 kJ
11. 555 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Mole Conversions

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

85. What is ΔH°_rxn for the following reaction?

NO₂(g) + CO(g) → CO₂(g) + NO(g)

Substance                ΔH°_f(kJ/mol)

NO(g)                        +90.4

NO₂(g)                     +33.85

CO(g)                      –110.5

CO₂(g)                     –393.5

339. 339.6 kJ
340. 379.8 kJ
341. C. –226.5 kJ
342. –339.6 kJ
343. –379.8 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

86. Solid sodium peroxide (Na₂O₂) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released if 327.2 g of oxygen gas is produced from the reaction of sodium peroxide and water under standard-state conditions?

Substance                ΔH°_f(kJ/mol)

Na₂O₂ (s)                 –510.9

NaOH(aq)               –469.6

H₂O(l)                     –285.8

1. 46,630 kJ
2. 1457 kJ
3. 6689 kJ
4. 3345 kJ
5. E. 2914 kJ

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Molar Mass

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: Writing and Balancing Chemical Equations

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

87. Sand is converted to pure silicon in a three-step process. The final step in this process is as follows.

SiCl₄(g) + 2Mg(s) → 2MgCl(s) + Si(s) ΔH°_rxn = –625.6 kJ/mol

What is the enthalpy change if 25.0 mol of silicon tetrachloride is converted to elemental silicon?

25. –25.0 kJ
26. –626 kJ
27. C. –1.56 × l0⁴ kJ
28. –3.13 × 10⁴ kJ
29. –3.13 × 10³ kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

88. The highly exothermic thermite reaction, in which aluminum reduces iron(III) oxide to elemental iron, has been used by railroad repair crews to weld rails together.

2Al(s) + Fe₂O₃(s) → 2Fe(s) + Al₂O₃(s) ΔH°_rxn = –847.6 kJ/mol

What mass of iron is formed if 725 kJ of heat are released?

23. 23.9 g
24. 47.8 g
25. 65.3 g
26. D. 5 g
27. 112 g

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Molar Mass

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

 

 

89. Using Hess’s law, what is ΔH°_rxn for the following reaction?

WO₃(s) + 3H₂(g) → W(s) + 3H₂O(g)

2W(s) + 3O₂(g) →2WO₃(s)                     ΔH°_rxn = –1685.8 kJ/mol

2H₂(g) + O₂(g) → 2H₂O(g)                      ΔH°_rxn = –483.6 kJ/mol

117. A. 5 kJ/mol
118. 235.0 kJ/mol
119. 359.3 kJ/mol
120. 1202.2 kJ/mol
121. 2169.4 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Thermochemistry

 

90. Using Hess’s law, what is ΔH°_rxn for the following reaction?

NO(g) + O(g) → NO₂(g)

NO(g) + O₃(g) → NO₂(g) +O₂(g)            ΔH°_rxn = –198.8 kJ/mol

O₃(g) → 3/2 O₂(g)                                   ΔH°_rxn = –142.2 kJ/mol

O₂(g) → 2O(g)                                        ΔH°_rxn = +498.8 kJ/mol

839. –839.8 kJ/mol
840. B. –306.0 kJ/mol
841. 157.9 kJ/mol
842. 394.9 kJ/mol
843. 442.3 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Thermochemistry

 

91. Using Hess’s law, what is the standard enthalpy of formation, ΔH°_f of manganese(II) oxide, MnO(s)?

2MnO₂(s) → 2MnO(s) +O₂(g)                ΔH°_rxn = +272.0 kJ/mol

MnO₂(s) + Mn(s) → 2MnO(s)                ΔH°_rxn = –248.9 kJ/mol

520. –520.9 kJ/mol
521. –396.5 kJ/mol
522. C. –384.9 kJ/mol
523. –147.6 kJ/mol
524. 24 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

92. What is ΔH°_rxn for the decomposition of calcium carbonate to calcium oxide and carbon dioxide?

CaCO₃(s) → CaO(s) + CO₂(g)

Substance                ΔH°_f(kJ/mol)

CaCO₃(s)                 –1206.9

CaO(s)                     –635.6

CO₂(g)                     –393.5

2236. –2236.0 kJ/mol
2237. –1449.0 kJ/mol
2238. –177.8 kJ/mol
2239. D. 8 kJ/mol
2240. 2236.0 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

93. Aluminum oxide can be reduced to aluminum metal using carbon, the other reaction product being carbon monoxide. What is the enthalpy change if 12.50 g of aluminum is produced by this method?

Substance                ΔH°_f(kJ/mol)

CO(g)                      –110.5

Al₂O₃(s)                  –1669.8

310. A. 0 kJ
311. 386.8 kJ
312. 412.4 kJ
313. 773.6 kJ
314. 824.8 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Molar Mass

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: Writing and Balancing Chemical Equations

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

94. Using Hess’ law, what is ΔH°_rxn at 25°C for the following reaction?

ClF(g) + F₂(g) → ClF₃(g)2ClF(g) + O₂(g) → Cl2O(g) + OF₂(g)             ΔH°_rxn = +167.4kJ/mol

2ClF₃(g) + 2O₂(g) → Cl₂O(g) +3OF₂(g)                                                 ΔH°_rxn = +341.4kJ/mol

2F₂(g) + O₂(g) → 2OF₂(g)                                                                       ΔH°_rxn = –43.4 kJ/mol

217. –217.5 kJ/mol
218. –130.2 kJ/mol
219. 217.5 kJ/mol
220. D. –108.7 kJ/mol
221. 465.4 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Thermochemistry

 

 

 

95. Ethanol, C₂H₅OH, is promoted as a clean fuel and is used as an additive in many gasoline mixtures. Calculate the ΔH°_rxn for the combustion of ethanol.

Substance                ΔH°_f(kJ/mol)

C₂H₅OH(l)              –277.0

CO₂(g)                     –393.5

H₂O(g)                    –241.8

1235. A. –1235.4 kJ
1236. –751.8 kJ
1237. –358.3 kJ
1238. 358.3 kJ
1239. 1235.4 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: Writing and Balancing Chemical Equations

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

96. What is ΔH°_rxn for the following reaction?

SiO₂(s) + 4HCl(g) → SiCl₄(g) + 2H₂O(g)

Substance                ΔH°_f(kJ/mol)

SiO₂(s)                    –859.3

SiCl₄(g)                   –662.8

HCl(g)                     –92.3

H₂O(g)                    –241.8

1856. –1856.2 kJ/mol
1857. –1372.6 kJ/mol
1858. –47.0 kJ/mol
1859. D. 1 kJ/mol
1860. 530.6 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

97. The bond enthalpy of the Br–Cl bond is equal to ΔH°_rxn for the following reaction.

BrCl(g) → Br(g) + Cl(g)

Using the following data, what is the bond enthalpy of the Br–Cl bond?

Br₂(l) → Br₂(g)                       ΔH°_rxn = 30.91 kJ/mol

Br₂(g) → 2Br(g)                      ΔH°_rxn = 192.9 kJ/mol

Cl₂(g) → 2Cl(g)                       ΔH°_rxn = 243.4 kJ/mol

Br₂(l) + Cl₂(g) → 2BrCl(g)      ΔH°_rxn = 29.2 kJ/mol

219. A. 0 kJ/mol
220. 203.5 kJ/mol
221. 14.6 kJ/mol
222. 438.0 kJ/mol
223. 407.0 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Chemical Bonding

Topic: Thermochemistry

 

 

 

98. Ozone (O₃) in the atmosphere can be converted to oxygen gas by reaction with nitric oxide (NO). (Nitrogen dioxide is also produced in the reaction.) What is the enthalpy change when 8.50 L of ozone at a pressure of 1.00 atm and 25°C reacts with 12.00 L of nitric oxide at the same initial pressure and temperature (R = 0.0821 L atm/mol K)? [ΔH°_f(NO) = 90.4 kJ/mol; ΔH°_f(NO₂) = 33.85 kJ/mol; ΔH°_f(O₃) = 142.2 kJ/mol]
99. A. –69.1 kJ
100. –19.7 kJ
101. –1690 kJ
102. –97.6 kJ
103. –167 kJ

 

Blooms: 5. Evaluate

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Limiting Reactant

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Subtopic: Writing and Balancing Chemical Equations

Topic: Gases

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

99. An important step in the synthesis of nitric acid is the conversion of ammonia to nitric oxide according to the following balanced chemical equation. What is ΔH°_rxn for this reaction?

4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

Substance                ΔH°_f(kJ/mol)

NH₃(g)                    –46.3

NO(g)                        90.3

H₂O(g)                    –241.8

1274. –1274.8 kJ/mol
1275. B. –904.4 kJ/mol
1276. –240.2 kJ/mol
1277. –197.8kJ
1278. 197.8 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

100. What is ΔH°_rxn for the following reaction?

H₃AsO₄(aq) + 4H₂(g) → AsH₃(g) + 4H₂O(l)

Substance                ΔH°_f(kJ/mol)

AsH₃(g)                   171.5

H₃AsO₄(aq)            –904.6

H₂O(l)                     –285.8

1876. –1876.3 kJ/mol
1877. –1018.9 kJ/mol
1878. –790.3 kJ/mol
1879. –410.1 kJ/mol
1880. E. –67.1 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

101. Suppose a new metallic element X is discovered, and its reactions with oxygen gas and chlorine gas at 298 K are studied.

Trial	Reaction	ΔHºrxn (kJ/mol)
1	4X(s) + 3O2(g) → 2X2O3(s)	–600
2	2X(s) + 3Cl2(g) → 2XCl3(s)	–800
3	4XCl3(s) + 3O2(g) →X2O3(s)+6Cl2(g)	–200

However, it is later discovered that one of the samples was contaminated, and the ΔHº_rxn value from this trial is not reliable. Which trial had the contaminated sample, and what should the correct value of ΔHº_rxn be for this trial?

1. A. Trial 1 had the contaminated sample; its ΔHº_rxn value should be –900 kJ/mol.
2. Trial 2 had the contaminated sample; its ΔHº_rxn value should be +100 kJ/mol.
3. Trial 3 had the contaminated sample; its ΔHº_rxn value should be –1000 kJ/mol.
4. Trial 3 had the contaminated sample; its ΔHº_rxn value should be +1000 kJ/mol.
5. Not enough information is provided; all three trials must be redone.

 

Blooms: 5. Evaluate

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

 

 

102. Atoms A and Z may form either single bonds or double bonds. Shown is an energy diagram for the formation of a single bond between A and Z from the individual atoms in the gas phase.

 

Which diagram below corresponds to the reaction A(g) + Z(g) → A=Z(g)?

4. D.

 

Blooms: 5. Evaluate

Difficulty: Hard

Gradable: automatic

Subtopic: Covalent Bonding

Subtopic: Enthalpy (Heats of Reaction)

Topic: Chemical Bonding

Topic: Thermochemistry

 

 

 

103. Consider the following two representations of chemical reactions. Each sphere represents 1 mol of atoms.

 

 

What is ΔHº_rxn for the following reaction? CS(g) + O(g) → CO(g) + S(g)

1. A. –359 kJ/mol
2. 1434 kJ/mol
3. –7142 kJ/mol
4. –1434 kJ/mol
5. 7142 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Hess’s Law

Topic: Thermochemistry

 

 

 

104. Which represents the formation reaction for XeF₄(g)? Each sphere represents 1 mol of atoms.

 

1. B.

 

 

 

Blooms: 5. Evaluate

Difficulty: Hard

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

 

 

105. Suppose a 0.500-g sample of an organic compound is analyzed via bomb calorimetry. The temperature of the calorimeter is measured over time. At t = 5 min, the combustion reaction is initiated. Below is a plot of the data that are obtained.

Suppose the experiment is repeated under identical conditions, but with a 1.000-g sample of the organic compound. What might a plot of the resulting data look like?

3. C.

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Topic: Thermochemistry

 

 

 

106. Suppose a sample of gas undergoes the following change of state.

Which statement(s) is/are true concerning this change of state?

1. w must be positive.
2. w must be negative.

iii. q must be positive.

1. q must be negative.
2. I only
3. B. II only
4. II and III
5. II and IV
6. I and III

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

107. Cold packs, whose temperatures are lowered when ammonium nitrate dissolves in water, are carried by athletic trainers when transporting ice is not possible. Which of the following is true of this reaction?
108. ΔH< 0, process is exothermic
109. ΔH> 0, process is exothermic
110. ΔH< 0, process is endothermic
111. D. ΔH> 0, process is endothermic
112. ΔH = 0, since cold packs are sealed

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

108. A student used a bomb calorimeter to determine the heat of combustion of an unknown compound. If the student ignored the heat capacity of the bomb calorimeter, the heat capacity of the unknown compound would be _________ the accepted value.
109. A. greater than (i.e., less negative)
110. less than (i.e., more negative)
111. equal to

 

Blooms: 4. Analyze

Difficulty: Hard

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Subtopic: Enthalpy (Heats of Reaction)

Topic: Thermochemistry

 

109. Which of the following processes always results in an increase in the energy of a system?
110. The system loses heat and does work on the surroundings.
111. The system gains heat and does work on the surroundings.
112. The system loses heat and has work done on it by the surroundings.
113. D. The system gains heat and has work done on it by the surroundings.
114. None of these is always true.

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

 

 

110. To which one of the following reactions, occurring at 25^oC, does the symbol ΔH^o_f [H₂SO₄(l)] refer?
111. A. H₂(g) + S(s) + 2O₂(g) <—–> H₂SO₄(l)
112. H₂SO₄(l) <—–> H₂(g) + S(s) + 2O₂(g)
113. H₂(g) + S(g) + 2O₂(g) <—–> H₂SO₄(l)
114. H₂SO₄(l) <—–> 2 H(g) + S(s) + 4O(g)
115. 2H(g)+S(g)+4O(g) <—–> H₂SO₄(l)

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Topic: Thermochemistry

 

111. Which of the following is incorrectly matched?
112. Radiant energy; solar energy able to influence global climate patterns
113. B. Thermal energy; related to temperature irrespective of the volume
114. Energy; capacity to do work
115. Chemical energy; potential energy

 

Blooms: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Units of Energy

Topic: Thermochemistry

 

112. For which of the substances below is ΔH^o_f = 0?
113. A. O₂(g)
114. N₂(l)
115. Na(g)
116. Xe(l)
117. A and B

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

113. Chemical reactions in a bomb calorimeter occur at constant pressure.

FALSE

 

Blooms: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: Calorimetry (Measuring Heats of Reaction)

Topic: Thermochemistry

 

114. The work done on the surroundings by the expansion of a gas is w = –PΔV.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

115. The heat absorbed by a system at constant pressure is equal to ΔU + PΔV.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

116. In an endothermic process, heat is absorbed by the system.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

117. The enthalpy of vaporization of a compound is always positive.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Phase Changes

Subtopic: System/Surroundings and Heat/Work

Topic: Intermolecular Forces

Topic: Thermochemistry

 

118. A home aquarium is an example of an open system.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

119. All elements in their standard state have an enthalpy of formation equal to zero.

TRUE

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

120. ΔH does not depend on the path of a reaction, but ΔU does.

FALSE

 

Blooms: 2. Understand

Difficulty: Medium

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

121. The enthalpy of formation of a liquid is always larger than the enthalpy of formation of the gas of the same compound.

FALSE

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

122. In an endothermic reaction, in going from the reactants to the products at the same temperature, the value of q is negative.

FALSE

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: automatic

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

123. The statement, “Energy can neither be destroyed nor created,” is the _____________.

first law of thermodynamics

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Topic: Thermochemistry

 

 

 

124. The enthalpy change for making one mole of a compound from its elements is called the

_____________.

enthalpy of formation

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

125. The standard temperature is _____; the standard concentration of a solution is _______; and the standard pressure is _____.

usually 25°C; 1 M; 1 atm or atmospheric pressure

 

Blooms: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

126. ___________ is the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.

Specific heat

 

Blooms: 1. Remember

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

127. A(n) ___________ __________ is a process where heat is absorbed from the surroundings.

endothermic process

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

128. A(n) ___________ __________ is a process where heat is released to the surroundings.

exothermic process

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

129. The sign of q when heat is absorbed by the system is ___________.

positive

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

130. The sign of w when work is done on the system by the surroundings is ___________.

positive

 

Blooms: 2. Understand

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

131. Internal energy = _________ + ___________

heat (q) + work (w)

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

132. The sign of w when work is done by the system on the surroundings is _____________.

negative

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

133. The sign of q when heat is released by the system is _______________.

negative

 

Blooms: 3. Apply

Difficulty: Easy

Gradable: automatic

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

134. Clearly state the thermodynamic standard state of a. an element or compound.
135. a solute.

 

1. Standard state is the stable form of the substance at 1 atm and a specified temperature, usually 25 degreesC.
2. Standard state is a solution of 1 M concentration.

 

Difficulty: Medium

Gradable: manual

 

135. a. Explain fully what is meant by the term “state function.”
136. (i) Give two examples of thermodynamic quantities which are state functions.

(ii) Give two examples of thermodynamic quantities which are not state functions.

 

1. A state function depends only on the initial and final states, not on its history or the path followed in a process.
2. (i) internal energy, enthalpy (and possibly T, P, etc.)

(ii) heat and work

 

Blooms: 3. Apply

Difficulty: Medium

Gradable: manual

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

136. A 100.-g sample of Cu is heated to 400.^oC and then plunged into 1000. g of water at 22.6^oC. What is the final temperature? Specific heat capacity: Cu: 0.385 J/g·°C;water: 4.184 J/g·°C

26^oC

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: manual

Subtopic: First Law of Thermodynamics (Conservation of Energy)

Topic: Thermochemistry

 

137. The enthalpy of combustion of acetylene (C₂H₂) is described by

C₂H₂(g) + 5/2O₂(g) → 2CO₂(g) + H₂O(l) ΔH°_rxn = –1299 kJ/mol

Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation: ΔH°_f(CO₂(g)) = –393.5 kJ/mol; ΔH°_f(H₂O(l)) = –285.8 kJ/mol

226 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: manual

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Stoichiometry and Chemical Reactions

Topic: Thermochemistry

 

138. Given the following ΔH° values,

H₂(g) + ½O₂(g) → H₂O(l) ΔH°_f = –285.8 kJ

H₂O₂(l) → H₂(g) + O₂(g) ΔH°_rxn = 187.6 kJ

calculate ΔH°_rxn for the reaction H₂O₂(l) → H₂O(l) + ½O₂(g),

–98.2 kJ/mol

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: manual

Subtopic: Hess’s Law

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)

Topic: Thermochemistry

 

139. When an automobile engine starts, the metal parts immediately begin to absorb heat released during the combustion of gasoline. How much heat will be absorbed by a 165-kg iron engine block when the temperature rises from 15.7°C to 95.7°C? (The specific heat of iron is 0.489 J/g·°C.)

6450kJ

 

Blooms: 4. Analyze

Difficulty: Easy

Gradable: manual

Subtopic: System/Surroundings and Heat/Work

Topic: Thermochemistry

 

140. At body temperature 2404 joules of energy are required to evaporate 1.00 g of water. After vigorous exercise, a person feels chilly because the body is giving up heat to evaporate the perspiration. A typical person perspires 25 mL of water after 20. minutes of exercise. How much body heat is this person using to evaporate this water?

60,100 J

 

Blooms: 4. Analyze

Difficulty: Medium

Gradable: manual

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Phase Changes

Topic: Intermolecular Forces

Topic: Thermochemistry

 

141. Thunderstorms are powered by the heat released when water vapor changes to rain drops. How much heat is released when a gallon of rain falls? (1 gal = 3,785 g; specific heat of vaporization of water = 2,262 J/g)

8,562 kJ

 

Blooms: 4. Analyze

Difficulty: Medium

Subtopic: Enthalpy (Heats of Reaction)

Subtopic: Phase Changes

Topic: Intermolecular Forces

Topic: Thermochemistry

 

 

 

                                                Category                                                                                                                                                                                       # of Questions

Blooms: 1. Remember                                                                                                                                               2

Blooms: 2. Understand                                                                                                                                             21

Blooms: 3. Apply                                                                                                                                                     17

Blooms: 4. Analyze                                                                                                                                                  86

Blooms: 5. Evaluate                                                                                                                                                 13

Difficulty: Easy                                                                                                                                                        40

Difficulty: Hard                                                                                                                                                        22

Difficulty: Medium                                                                                                                                                   78

Gradable: automatic                                                                                                                                                133

Gradable: manual                                                                                                                                                      7

Subtopic: Calculating Amounts of Reactant and Product (including solutions)                                                       1

Subtopic: Calorimetry (Measuring Heats of Reaction)                                                                                            11

Subtopic: Covalent Bonding                                                                                                                                     1

Subtopic: Enthalpy (Heats of Reaction)                                                                                                                   53

Subtopic: First Law of Thermodynamics (Conservation of Energy)                                                                       10

Subtopic: Hess’s Law                                                                                                                                               20

Subtopic: Limiting Reactant                                                                                                                                      1

Subtopic: Molar Mass                                                                                                                                               8

Subtopic: Mole Conversions                                                                                                                                     6

Subtopic: Phase Changes                                                                                                                                           3

Subtopic: Standard Enthalpies of Formation and Reaction (ΔH^o, ΔH^o)                                                                  35

Subtopic: System/Surroundings and Heat/Work                                                                                                      74

Subtopic: Types of Chemical Reactions (Acid-Base, REDOX, Displacement, etc.)                                               1

Subtopic: Units of Concentration                                                                                                                              1

Subtopic: Units of Energy                                                                                                                                         8

Subtopic: Writing and Balancing Chemical Equations                                                                                             4

Topic: Aqueous Solutions                                                                                                                                         1

Topic: Chemical Bonding                                                                                                                                         2

Topic: Gases                                                                                                                                                              1

Topic: Intermolecular Forces                                                                                                                                    3

Topic: Stoichiometry and Chemical Reactions                                                                                                        22

Topic: Thermochemistry                                                                                                                                         139