Test Bank For Chemistry 11th Edition by Raymond Chang A+

$35.00
Test Bank For Chemistry 11th Edition by Raymond Chang A+

Test Bank For Chemistry 11th Edition by Raymond Chang A+

$35.00
Test Bank For Chemistry 11th Edition by Raymond Chang A+

Chapter 6: Thermochemistry

1. Radiant energy is
A) the energy stored within the structural units of chemical substances.
B) the energy associated with the random motion of atoms and molecules.
C) solar energy, i.e. energy that comes from the sun.
D) energy available by virtue of an object’s position.
Ans: C Category: Easy Section: 6.1

2. Thermal energy is
A) the energy stored within the structural units of chemical substances.
B) the energy associated with the random motion of atoms and molecules.
C) solar energy, i.e. energy that comes from the sun.
D) energy available by virtue of an object’s position.
Ans: B Category: Easy Section: 6.1

3. Chemical energy is
A) the energy stored within the structural units of chemical substances.
B) the energy associated with the random motion of atoms and molecules.
C) solar energy, i.e. energy that comes from the sun.
D) energy available by virtue of an object’s position.
Ans: A Category: Easy Section: 6.1

4. Potential energy is
A) the energy stored within the structural units of chemical substances.
B) the energy associated with the random motion of atoms and molecules.
C) solar energy, i.e. energy that comes from the sun.
D) energy available by virtue of an object’s position.
Ans: D Category: Easy Section: 6.1

5. Heat is
A) a measure of temperature.
B) a measure of the change in temperature.
C) a measure of thermal energy.
D) a measure of thermal energy transferred between two bodies at different temperature.
Ans: D Category: Medium Section: 6.2

6. An endothermic reaction causes the surroundings to
A) warm up. D) decrease in temperature.
B) become acidic. E) release CO2.
C) condense.
Ans: D Category: Easy Section: 6.2

7. An exothermic reaction causes the surroundings to
A) increase in temperature D) decrease in temperature.
B) become acidic. E) release CO2.
C) expand.
Ans: A Category: Easy Section: 6.2

8. Aluminum metal has a specific heat of 0.900 J/g·°C. Calculate the amount of heat required to raise the temperature of 10.5 moles of Al from 30.5 °C to 225°C.
A) 1.84 kJ B) 2.41 kJ C) 65.1 kJ D) 49.6 kJ E) 57.3 kJ
Ans: D Category: Medium Section: 6.5

9. Given the specific heat for aluminum is 0.900 J/g·°C, how much heat is released when a 3.8 g sample of Al cools from 450.0°C to 25°C.
A) 54 J B) 60 J C) 86 J D) 1.5 kJ E) 1.7 kJ
Ans: D Category: Medium Section: 6.5

10. Calculate the amount of heat necessary to raise the temperature of 135.0 g of water from 50.4°F to 85.0°F. The specific heat of water = 4.184 J/g·°C.
A) 1.1 kJ B) 10.9 kJ C) 16.6 kJ D) 19.5 kJ E) 48.0 kJ
Ans: B Category: Medium Section: 6.5

11. How much heat is required to raise the temperature of 1.5 x 103 g of water from 45°F to 130.°F? The specific heat of water is 4.184 J/g·°C.
A) 3.0 x 101 kJ D) 5.3 x 102 kJ
B) 3.0 x 102 kJ E) 8.2 x 102 kJ
C) 3.4 x 102 kJ
Ans: B Category: Medium Section: 6.5

12. Three separate 3.5g blocks of Al, Cu, and Fe at 25 °C each absorb 0.505 kJ of heat. Which block reaches the highest temperature? The specific heats of Al, Cu, and Fe are 0.900 J/g·°C, 0.385J/g·°C, and 0.444 J/g·°C, respectively.
A) Al B) Cu C) Fe D) Al and Cu E) Fe and Cu
Ans: B Category: Easy Section: 6.5

13. A beaker contains 115 g of ethanol at 18.2°C. If the ethanol absorbs 1125 J of heat without losing heat to the surroundings, what will be the final temperature of the ethanol? The specific heat of ethanol is 2.46 J/g°C.
A) 4.08°C B) 14.1°C C) 18.4°C D) 22.2°C E) 36.4°C
Ans: D Category: Medium Section: 6.5

14. A 22.0 g block of copper at 45°C absorbs 2.50 kJ of heat. Given the specific heat of Cu is 0.385 J/g·°C what will be the final temperature of the Cu?
A) 45°C B) 340.°C C) 295°C D) 30.°C E) 250.°C
Ans: B Category: Medium Section: 6.5

15. If 10.6 moles of water at 35°C absorbs 12.30 kJ, what is the final temperature of the water? The specific heat of water is 4.184 J/g·°C.
A) 15°C B) 20°C C) 35°C D) 50.°C E) 312°C
Ans: D Category: Medium Section: 6.5

16. A 135 g sample of H2O at 85°C is cooled. The water loses a total of 15 kJ of energy in the cooling process. What is the final temperature of the water? The specific heat of water is 4.184 J/g·°C.
A) 27°C B) 58°C C) 70°C D) 84°C E) 112°C
Ans: B Category: Medium Section: 6.5

17. 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?
A) 0.385 J/g·°C D) 24.5 J/g·°C
B) 1.32 J/g·°C E) 1.83 × 104 J/g·°C
C) 2.60 J/g·°C
Ans: A Category: Easy Section: 6.5

18. The specific heat of gold is 0.129 J/g·°C. What is the molar heat capacity of gold?
A) 0.039 J/mol·°C D) 39.0 kJ/mol·°C
B) 0.129 J/mol·°C E) 197 J/mol·°C
C) 25.4 J/mol·°C
Ans: C Category: Easy Section: 6.5

19. Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50.0 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
A) will be higher than 50°C.
B) will be lower than 50°C.
C) will be exactly 50°C.
D) is unrelated to the composition of the blocks.
E) cannot be predicted.
Ans: B Category: Medium Section: 6.5

20. When 0.7521 g of benzoic acid was burned in a calorimeter containing 1,000. 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.
A) 1.34 kJ/°C D) 15.87 kJ/°C
B) 4.18 kJ/°C E) 752.1 kJ/°C
C) 5.52 kJ/°C
Ans: A Category: Medium Section: 6.5

21. Naphthalene combustion can 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 calorimeter containing 1,000. g of water, a temperature rise of 4.21°C was observed. What is the heat capacity of the bomb calorimeter excluding the water?
A) 1.76 kJ/°C B) 3.64 kJ/°C C) 7.8 kJ/°C D) 15.3 kJ/°C E) 32.9 kJ/°
Ans: B Category: Medium Section: 6.5

22. Which of the following processes is exothermic?
A) CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(l)
B) CO2(g) + 2 H2O(l)  CH4(g) + 2 O2(g)
C) CO2(s)  CO2(g)
D) H2O(l)  H2O(g)
E) 6 H2O(g) + 4 CO2(g)  2 C2H6(g) + 7 O2(g)
Ans: A Category: Easy Section: 6.2

23. Which of the following processes is exothermic, given the following:
N2(g) + 2 O2(g)  N2O4(l) H° = 9.67 kJ/mol
N2(g) + 2 O2(g)  2 NO2(g) H° = 67.70 kJ/mol
A) 2 N2(g) + 4 O2(g)  2 N2O4(l)
B) ½ N2(g) + O2(g)  ½ N2O4(l)
C) N2O4(l)  N2(g) + 2 O2(g)
D) 2 N2(g) + 4 O2(g)  2 NO2(g) + N2O4(l)
E) 2 N2(g) + 4 O2(g)  4 NO2(g)
Ans: C Category: Easy Section: 6.6

24. Which of the following processes is endothermic, given the following:
S(s) + O2(g)  SO2(g) H = –299 kJ/mol
S(s) + 3/2 O2(g)  SO3(g) H = –395 kJ/mol
A) 2 S(s) + 2 O2(g)  2 SO2(g)
B) ½ S(s) + ½ O2(g)  ½ SO2(g)
C) 2 S(s) + 5/2 O2(g)  SO2(g) + SO3(g)
D) SO3(g)  S(s) + 3/2 O2(g)
E) 2 S(s) + 3 O2(g)  2 SO3(g)
Ans: D Category: Easy Section: 6.6

25. Which of the following processes is endothermic?
A) O2(g) + 2H2(g)  2H2O(g)
B) H2O(g)  H2O(l)
C) 3O2(g) + 2CH3OH(g)  2CO2(g) + 2H2O(g)
D) H2O(s)  H2O(l)
Ans: D Category: Easy Section: 6.4

26. A 100. mL sample of 0.200 M aqueous hydrochloric acid is added to 100. mL of 0.200 M aqueous ammonia in a calorimeter whose heat capacity (excluding any water) is 480. J/K. The following reaction occurs when the two solutions are mixed.
HCl(aq) + NH3(aq)  NH4Cl(aq)
The temperature increase is 2.34°C. Calculate H per mole of HCl and NH3 reacted.
A) –154 kJ/mol D) 154 kJ/mol
B) –1.96 kJ/mol E) 485 kJ/mol
C) 1.96 kJ/mol
Ans: A Category: Difficult Section: 6.5

27. A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/°C. If the temperature rise of the calorimeter with water was 0.570°C, calculate the enthalpy of combustion of magnesium.
Mg(s) + 1/2O2(g)  MgO(s)
A) –3280 kJ/mol D) 106 kJ/mol
B) –602 kJ/mol E) 435 kJ/mol
C) –24.8 kJ/mol
Ans: B Category: Difficult Section: 6.5

28. The reaction that represents the standard enthalpy of formation for acetone (CH3COCH3), a common ingredient in nail polish remover is:
A) 3 C(graphite) + 3 H2(g) + ½ O2(g)  CH3COCH3(l)
B) 6 C(diamond) + 6 H2(g) + O2(g)  2 CH3COCH3(l)
C) 3 C(diamond) + 3 H2(g) + ½ O2(g)  CH3COCH3(l)
D) CH3COCH3(l)  3 C(graphite) + 3 H2(g) + ½ O2(g)
E) CH3COCH3(l) + 4 O2(g)  3 CO2(g) + 3 H2O(g)
Ans: A Category: Medium Section: 6.6

29. The reaction that represents the standard enthalpy of formation for sucrose (C12H22O11) is:
A) C12H22O11(s) + 12 O2  12 CO2(g) + 11 H2O(g)
B) 12 C(diamond) + 11 H2(g) + 11/2 O2(g)  C12H22O11(s)
C) 12 C(graphite) + 11 H2(g) + 11/2 O2(g)  C12H22O11(s)
D) 24 C(diamond) + 22 H2(g) + 11 O2(g)  2 C12H22O11(s)
E) C12H22O11(s)  12 C(graphite) + 11 H2(g) + 11/2 O2(g)
Ans: C Category: Medium Section: 6.6

30. The reaction that represents the standard enthalpy of formation for benzene (C6H6) is:
A) 6 C(diamond) + 3 H2(g)  C6H6(l)
B) 6 C(graphite) + 6 H(g)  C6H6(l)
C) C6H6(l) + 15/2 O2(g)  6 CO2(g) + 3 H2O(g)
D) 6 C(graphite) + 3 H2(g)  C6H6(l)
E) C6H6(l)  6 C(graphite) + 3 H2(g)
Ans: D Category: Medium Section: 6.6

31. Which of the following has a H°f = 0 kJ/mol?
A) CO2(g) B) O3(g) C) Cl-(aq) D) NH3(aq) E) I2(s)
Ans: E Category: Easy Section: 6.6

32. Which of the following has a H°f = 0 kJ/mol?
A) NO(g) B) CS2(l) C) Fe2+(aq) D) H2O(l) E) N2(g)
Ans: E Category: Easy Section: 6.6

33. 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 (H°f) of NaF(s)?
A) -570 kJ/mol D) 24.8 kJ/mol
B) –24.8 kJ/mol E) 570 kJ/mol
C) –7.8 kJ/mol
Ans: A Category: Medium Section: 6.6

34. When 18.5 g of HgO(s) is decomposed to form Hg(l) and O2(g), 7.75 kJ of heat is absorbed at standard-state conditions. What is the standard enthalpy of formation (H°f) of HgO(s)?
A) –90.7 kJ/mol D) 27.9 kJ/mol
B) –7.75 kJ/mol E) 143 kJ/mol
C) 0.419 kJ/mol
Ans: A Category: Medium Section: 6.6

35. Ethanol undergoes combustion in oxygen to produce carbon dioxide gas and liquid water. The standard heat of combustion of ethanol, C2H5OH(l), is –1366.8 kJ/mol. Given that H°f[CO2(g)] = –393.5 kJ/mol and H°f[H2O(l)] = –285.8 kJ/mol, what is the standard enthalpy of formation of ethanol?
A) –687.6 kJ/mol D) 1,367 kJ/mol
B) –277.6 kJ/mol E) 3,010 kJ/mol
C) 687.6 kJ/mol
Ans: B Category: Difficult Section: 6.6

36. Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data: heat of combustion of C2H4(g) = –1411 kJ/mol; H°f[CO2(g)] = –393.5 kJ/mol; H°f[H2O(l)] = –285.8 kJ/mol.
A) 52 kJ/mol D) 1.41 × 103 kJ/mol
B) 87 kJ/mol E) 2.77 × 103 kJ/mol
C) 731 kJ/mol
Ans: A Category: Difficult Section: 6.6

37. Octane (C8H18) undergoes combustion according to the following thermochemical equation:
2C8H18(l) + 25O2(g)  16CO2(g) + 18H2O(l) H°rxn = –11,020 kJ/mol.
Given that H°f[CO2(g)] = –393.5 kJ/mol and H°f[H2O(l)] = –285.8 kJ/mol, calculate the standard enthalpy of formation of octane.
A) –210 kJ/mol D) –420 kJ/mol
B) –11,230 kJ/mol E) 420 kJ/mol
C) 22,040 kJ/mol
Ans: A Category: Medium Section: 6.6

38. Acetylene (C2H2) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. Given H°f[CO2(g)] = –393.5 kJ/mol, H°f[H2O(g)] = –241.8 kJ/mol, and H°f [C2H2(g)] = 226.6 kJ/mol, how much energy is released (kJ) when 10.5 moles of acetylene is burned?
A) 2,510.8 kJ B) 26,400 kJ C) 13,200 kJ D) 52,700 kJ E) 9,050 kJ
Ans: C Category: Difficult Section: 6.6

39. Butane (C4H10) undergoes combustion in excess oxygen to generate gaseous carbon dioxide and water. Given H°f [C4H10(g)] = –124.7 kJ/mol, H°f[CO2(g)] = –393.5 kJ/mol, H°f[H2O(g)] = –241.8 kJ/mol, how much energy is released (kJ) when 8.30 g of butane is burned?
A) 22,100 kJ B) 2,658.3 kJ C) 379 kJ D) 759 kJ E) 2,910 kJ
Ans: C Category: Difficult Section: 6.6

40. Glycine, C2H5O2N, is important for biological energy. The combustion reaction of glycine is given by the equation
4C2H5O2N(s) + 9O2(g)  8CO2(g) + 10H2O(l) + 2N2(g) H°rxn = –3857 kJ/mol
Given that H°f[CO2(g)] = –393.5 kJ/mol and H°f[H2O(l)] = –285.8 kJ/mol, calculate the enthalpy of formation of glycine.
A) –3,178 kJ/mol D) –268.2 kJ/mol
B) –964 kJ/mol E) 2,149 kJ/mol
C) –537.2 kJ/mol
Ans: C Category: Medium Section: 6.6

41. 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, 42.62 kJ are released per gram of styrene. Find the standard enthalpy of formation of styrene at 25°C.
(Given: H°f[CO2(g)] = –393.5 kJ/mol, H°f[H2O(l)] = –285.8 kJ/mol, H°f[H2O(g)] = –241.8 kJ/mol)
A) 147.8 kJ/mol D) ~4249 kJ/mol
B) 323.8 kJ/mol E) ~8730 kJ/mol
C) ~636.7 kJ/mol
Ans: A Category: Difficult Section: 6.6

42. Given 2Al(s) + (3/2)O2(g)  Al2O3(s), H°f = –1,670 kJ/mol for Al2O3 (s).
Determine H° for the reaction 2Al2O3(s)  4Al(s) + 3O2(g).
A) –3,340 kJ/mol D) 1,670 kJ/mol
B) –1,670 kJ/mol E) 3,340 kJ/mol
C) –835 kJ/mol
Ans: E Category: Easy Section: 6.6

43. Calculate the standard enthalpy of formation of liquid methanol, CH3OH(l), using the following information:
C(graph) + O2  CO2(g)
H° = –393.5 kJ/mol
H2(g) + (1/2)O2  H2O(l)
H° = –285.8 kJ/mol
CH3OH(l) + (3/2)O2(g)  CO2(g) + 2H2O(l)
H° = –726.4 kJ/mol

A) –1,691.5 kJ/mol D) 47.1 kJ/mol
B) –238.7 kJ/mol E) 1691.5 kJ/mol
C) –47.1 kJ/mol
Ans: B Category: Medium Section: 6.6

44. Calculate the standard enthalpy change for the reaction
2C8H18(l) + 17O2(g)  16CO(g) + 18H2O(l).
Given:
2C8H18(l) + 25O2(g) 16CO2(g) + 18H2O(l)
H° = –11,020 kJ/mol
2CO(g) + O2(g)  2CO2(g)
H° = –566.0 kJ/mol

A) –10.450 kJ/mol D) 10,450 kJ/mol
B) –6,492 kJ/mol E) 15,550 kJ/mol
C) 6,492 kJ/mol
Ans: B Category: Medium Section: 6.6

45. During volcanic eruptions, hydrogen sulfide gas is given off and oxidized by air according to the following chemical equation:
2H2S(g) + 3O2(g)  2SO2(g) + 2H2O(g)
Calculate the standard enthalpy change for the above reaction given:
3S(s) + 2H2O(g)  2H2S(g) + SO2(g)
H° = 146.9 kJ/mol
S(s) + O2(g)  SO2(g)
H° = –296.4 kJ/mol

A) –1036.1 kJ/mol D) 443.3 kJ/mol
B) –742.3 kJ/mol E) 742.3 kJ/mol
C) –149.5 kJ/mol
Ans: A Category: Medium Section: 6.6

46. 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) H° = –11,020 kJ/mol
2CO(g) + O2(g)  2CO2(g) H° = –566.0 kJ/mol
A) –1.0454 × 104 kJ/mol D) 1.0454 × 104 kJ/mol
B) –8,756 kJ/mol E) 1.1586 × 104 kJ/mol
C) –6,492 kJ/mol
Ans: B Category: Medium Section: 6.6

47. Calculate the standard enthalpy change for the reaction
2A + 2A2 + 4AB + B  5A2B
Given:
2A + B  A2B
H° = – 25.0 kJ/mol
2A2B  2AB + A2
H° = 35.0 kJ/mol

A) – 95.0 kJ/mol D) 10.0 kJ/mol
B) – 60.0 kJ/mol E) 45.0 kJ/mol
C) – 15.0 kJ/mol
Ans: A Category: Medium Section: 6.6

48. Calculate the standard enthalpy change for the reaction
4A + 2B  2AB + A2
Given:
2A + B  A2B
H° = – 25.0 kJ/mol
2A2B  2AB + A2
H° = 35.0 kJ/mol

A) – 95.0 kJ/mol D) 10.0 kJ/mol
B) – 60.0 kJ/mol E) 45.0 kJ/mol
C) – 15.0 kJ/mol
Ans: C Category: Medium Section: 6.6

49. Calculate the heat required when 2.50 mol of A reacts with excess B and A2B according to the reaction:
2A + B + A2B  2AB + A2
Given:
2A + B  A2B
H° = – 25.0 kJ/mol
2A2B  2AB + A2
H° = 35.0 kJ/mol

A) 10.0 kJ B) 12.5 kJ C) 25.0 kJ D) 35.0 kJ E) 62.5 kJ
Ans: B Category: Medium Section: 6.6

50. How much heat (kJ) is evolved when 4.50 g of Fe2O3 is reacted with excess carbon monoxide using the equation below?
Fe2O3(s) + 3CO(g)  2 Fe(s) + 3 CO2(g) H°rxn = – 24.8 kJ/mol,
A) 0.699 kJ B) 2.10 kJ C) 17.9 kJ D) 24.8 kJ E) 112 kJ
Ans: A Category: Medium Section: 6.4

51. Given H2(g) + (1/2)O2(g)  H2O(l), H° = –286 kJ/mol, determine the standard enthalpy change for the reaction 2H2O(l)  2H2(g) + O2(g).
A) H° = –286 kJ/mol D) H° = +572 kJ/mol
B) H° = +286 kJ/mol E) H° = –143 kJ/mol
C) H° = –572 kJ/mol
Ans: D Category: Easy Section: 6.6

52. Pentaborane B5H9(s) burns vigorously in O2 to give B2O3(s) and H2O(l). Calculate Hrxn for the combustion of 5.00 mol of B5H9.
H°f[B2O3(s)] = –1,273.5 kJ/mol
H°f[B5H9(s)] = 73.2 kJ/mol
H°f[H2O(l)] = –285.8 kJ/mol
A) – 45,400 kJ D) – 9,090 kJ
B) 45,400 kJ E) – 8,790 kJ
C) – 22,700 kJ
Ans: C Category: Difficult Section: 6.6

53. Concerning the reaction
C(graphite) + O2(g)  CO2(g)
H° = –393 kJ/mol
how many grams of C(graphite) must be burned to release 275 kJ of heat?
A) 0.70 g B) 8.40 g C) 12.0 g D) 17.1 g E) 22.3 g
Ans: B Category: Medium Section: 6.4

54. The combustion of butane produces heat according to the equation
2C4H10(g) + 13O2(g)  8CO2(g) + 10H2O(l) H°rxn= –5,314 kJ/mol
How many grams of butane must be burned to release 1.00 × 104 kJ of heat?
A) 30.9 g B) 61.8 g C) 109 g D) 153 g E) 219 g
Ans: E Category: Medium Section: 6.4

55. The combustion of butane produces heat according to the equation
2C4H10(g) + 13O2(g)  8CO2(g) + 10H2O(l) H°rxn= –5,314 kJ/mol
How many grams of CO2 are produced per 1.00 × 104 kJ of heat released?
A) 23.4 g B) 44.0 g C) 82.3 g D) 187 g E) 662 g
Ans: E Category: Medium Section: 6.4

56. Given that CaO(s) + H2O(l)  Ca(OH)2(s), H°rxn = –64.8 kJ/mol, how many grams of CaO must react in order to liberate 525 kJ of heat?
A) 6.92 g B) 56.1 g C) 455 g D) 606 g E) 3.40 × 104 g
Ans: C Category: Medium Section: 6.4

57. The combustion of pentane produces heat according to the equation
C5H12(l) + 8O2(g)  5CO2(g) + 6H2O(l) H°rxn= –3,510 kJ/mol
How many grams of CO2 are produced per 2.50 × 103 kJ of heat released?
A) 0.0809 g B) 3.56 g C) 31.3 g D) 157 g E) 309 g
Ans: D Category: Medium Section: 6.4

58. An average home in Colorado requires 20. GJ of heat per month. How many grams of natural gas (methane) must be burned to supply this energy?
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l) H°rxn= –890.4 kJ/mol
A) 7.1 × 10–4 g D) 2.2 × 104 g
B) 1.4 × 103 g E) 3.6 × 105 g
C) 1.4 × 104 g
Ans: E Category: Medium Section: 6.4

59. Given the thermochemical equation 2SO2(g) + O2(g)  2SO3(g), H°rxn= –198 kJ/mol, how much heat is evolved when 600. g of SO2 is burned?
A) 5.46 × 10–2 kJ D) 3.71 × 103 kJ
B) 928 kJ E) 59,400 kJ
C) 1.85 × 103 kJ
Ans: B Category: Medium Section: 6.4

60. Determine the heat given off to the surroundings when 9.0 g of aluminum reacts according to the equation 2Al + Fe2O3  Al2O3 + 2Fe, H°rxn= –849 kJ/mol.
A) 1.4 × 102 kJ D) 2.5 × 103 kJ
B) 2.8 × 102 kJ E) 7.6 × 103 kJ
C) 5.6 × 102 kJ
Ans: A Category: Medium Section: 6.4

61. Find the heat absorbed from the surroundings when 15 g of O2 reacts according to the equation O + O2  O3, H°rxn= –103 kJ/mol.
A) 4.6 × 10–3 kJ B) 32 kJ C) 48 kJ D) 96 kJ E) 110 kJ
Ans: C Category: Medium Section: 6.4

62. Ethanol (C2H5OH) burns according to the equation
C2H5OH(l) + 3O2(g)  2CO2(g) + 3H2O(l), H°rxn = –1367 kJ/mol.
How much heat is released when 35.0 g of ethanol is burned?
A) 9.61 × 10–4 kJ B) 1,040 kJ C) 1,367 kJ D) 1,797 kJ E) 4.78 × 104 kJ
Ans: B Category: Medium Section: 6.4

63. Methanol (CH3OH) burns according to the equation
2CH3OH(l) + 3O2(g)  2CO2(g) + 4H2O(l), H°rxn = –1454 kJ/mol.
How much heat, in kilojoules, is given off when 75.0 g of methanol is burned?
A) 727 kJ D) 1.70 × 103 kJ
B) 3.22 × 103 kJ E) 3.41 × 103 kJ
C) 1.45 × 103 kJ
Ans: D Category: Medium Section: 6.4

64. Calcium oxide and water react in an exothermic reaction:
CaO(s) + H2O(l)  Ca(OH)2(s) H°rxn = –64.8 kJ/mol
How much heat would be liberated when 7.15 g CaO(s) is dropped into a beaker containing 152g H2O?
A) 1.97 × 10–3 kJ B) 8.26 kJ C) 508 kJ D) 547 kJ E) 555 kJ
Ans: B Category: Medium Section: 6.4

65. Solid sodium peroxide (Na2O2) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas. How much heat is released when 250.0 L of oxygen gas is produced from the reaction of sodium peroxide and water if the reaction is carried out in an open container at 1.000 atm pressure and 25°C?
(Given: H°f[Na2O2(s)] = –510.9 kJ/mol; H°f[NaOH(aq)] = –469.2 kJ/mol; H°f[H2O(l)] = –285.8 kJ/mol)
A) 141.7 kJ B) 1740 kJ C) 2900 kJ D) 3330 kJ E) 35,400 kJ
Ans: C Category: Difficult Section: 6.6

66. At 25°C, the standard enthalpy of formation of anhydrous sodium carbonate is –1130.9 kJ/mol, whereas the standard enthalpy of formation of sodium carbonate monohydrate is –1430.1 kJ/mol. Determine H° at 25°C for the reaction
Na2CO3(s) + H2O(l)  Na2CO3·H2O(s).
(Given: H°f[H2O(l)] = –285.8 kJ/mol)
A) –585.0 kJ/mol D) –156.3 kJ/mol
B) –299.2 kJ/mol E) –13.4 kJ/mol
C) –285.8 kJ/mol
Ans: E Category: Medium Section: 6.6

67. According to the first law of thermodynamics:
A) Energy is neither lost nor gained in any energy transformations.
B) Perpetual motion is possible.
C) Energy is conserved in quality but not in quantity.
D) Energy is being created as time passes. We have more energy in the universe now than when time began.
Ans: A Category: Easy Section: 6.3

68. The heat of solution of KCl is 17.2 kJ/mol and the lattice energy of KCl(s) is 701.2 kJ/mol. Calculate the total heat of hydration of 1.00 mol of gas phase K+ ions and Cl– ions.
A) –718 kJ B) –684 kJ C) 684 kJ D) 718 kJ E) None of these.
Ans: B Category: Medium Section: 6.7

69. The heat of solution of LiCl is –37.1 kJ/mol, and the lattice energy of LiCl(s) is 828 kJ/mol. Calculate the total heat of hydration of 1.00 mol of gas phase Li+ ions and Cl– ions.
A) –865 kJ B) –791 kJ C) 791 kJ D) 865 kJ E) None of these.
Ans: A Category: Medium Section: 6.7

70. The total heat of hydration of 1.00 mol of gas phase Li+ ions and Cl – ions is –865 kJ. The lattice energy of LiCl(s) is 828 kJ/mol. Calculate the heat of solution of LiCl.
A) –1,693 kJ/mol D) 1,693 kJ/mol
B) –37 kJ/mol E) None of these
C) 37 kJ/mol
Ans: B Category: Medium Section: 6.7

71. 10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H2O at 18.0°C.
If the following reaction occurs, then what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat? (the specific heat of water = 4.18 J/g·°C)
CaO(s) + H2O(l)  Ca(OH)2(s) H°rxn = –64.8 kJ/mol
A) 18.02°C B) 35.8°C C) 42.2°C D) 117°C E) 311°C
Ans: B Category: Medium Section: 6.5

72. The enthalpy change when a strong acid is neutralized by strong base is –56.1 kJ/mol. If 135 mL of 0.450 M HI at 23.15°C is mixed with 145 mL of 0.500 M NaOH, also at 23.15°C, what will the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/g·°C, and that the density of the final solution is that of water.)
A) 20.24°C B) 26.06°C C) 29.19°C D) 32.35°C E) 36.57°C
Ans: B Category: Difficult Section: 6.5

73. The enthalpy change when a strong acid is neutralized by strong base is –56.1 kJ/mol. If 12.0 mL of 6.00 M HBr at 21.30°C is mixed with 300. mL of 0.250 M NaOH, also at 21.30°C, what will the maximum temperature reached by the resulting solution? (Assume that there is no heat loss to the container, that the specific heat of the final solution is 4.18 J/g·°C, and that the density of the final solution is that of water.)
A) 18.20°C B) 24.40°C C) 24.53°C D) 34.25°C E) 101.8°C
Ans: B Category: Difficult Section: 6.5

74. Calculate the amount of work done, in joules, when 2.5 mole of H2O vaporizes at 1.0 atm and 25°C. Assume the volume of liquid H2O is negligible compared to that of vapor. (1 L·atm = 101.3 J)
A) 61.1 J B) 518 J C) 5.66 kJ D) 6.19 kJ E) 6,190 kJ
Ans: D Category: Medium Section: 6.3

75. A gas is compressed in a cylinder from a volume of 20.0 L to 2.0 L by a constant pressure of 10.0 atm. Calculate the amount of work done on the system.
A) –1.81 × 104 J B) –180 J C) 180 J D) 1.01 × 104 J E) 1.81 × 104 J
Ans: E Category: Medium Section: 6.3

76. Calculate the amount of work done against an atmospheric pressure of 1.00 atm when 500.0 g of zinc dissolves in excess acid at 30.0°C.
Zn(s) + 2H+(aq)  Zn2+(aq) + H2(g)
A) w = +22.4 kJ D) w = –2.52 kJ
B) w = +24.9 kJ E) w = –19.3 kJ
C) w = 0
Ans: E Category: Medium Section: 6.3

77. 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?

A) A B) B C) C D) D E) E
Ans: A Category: Medium Section: 6.3

78. Which of the following processes always results in an increase in the energy of a system?
A) The system loses heat and does work on the surroundings.
B) The system gains heat and does work on the surroundings.
C) The system loses heat and has work done on it by the surroundings.
D) The system gains heat and has work done on it by the surroundings.
E) None of these is always true.
Ans: D Category: Medium Section: 6.3

79. For which of these reactions will the difference between H° and E° be the greatest?
A) 2H2O2(l)  2H2O(l) + O2(g)
B) CaCO3(s)  CaO(s) +CO2(g)
C) NO(g) + O3(g)  NO2(g) + O2(g)
D) 2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O(l)
E) 4NH3(g) + 5O2(g)  4NO(g) + 6H2O(g)
Ans: D Category: Medium Section: 6.4

80. For which of these reactions will the difference between H° and E° be the smallest?
A) N2(g) + 3H2(g)  2NH3(g)
B) 4PH3(g)  P4(g) + 6H2(g)
C) H2(g) + Cl2(g)  2HCl(g)
D) CO2(g) + 2H2O(l)  CH4(g) + 2O2(g)
E) P4(s) + 10Cl2(g)  4PCl5(s)
Ans: C Category: Medium Section: 6.4

81. At 25°C, the following heats of reaction are known:
2ClF(g) + O2(g)  Cl2O(g) + F2O(g)
H°rxn = 167.4 kJ/mol
2ClF3(g) + 2O2(g)  Cl2O(g) + 3F2O(g)
H°rxn = 341.4 kJ/mol
2F2(g) + O2(g)  2F2O(g)
H°rxn = –43.4 kJ/mol
At the same temperature, use the above data to calculate the heat released (kJ) when 3.40 moles of ClF(g) reacts with excess F2:
ClF(g) + F2(g)  ClF3(g)
A) 109 kJ B) 233 kJ C) 370. kJ D) 465 kJ E) 1,580 kJ
Ans: C Category: Medium Section: 6.6

82. The bond enthalpy of the Br–Cl bond is equal to H° for the reaction
BrCl(g)  Br(g) + Cl(g).
Use the following data to find the bond enthalpy of the Br–Cl bond.
Br2(l)  Br2(g)
H° = 30.91 kJ/mol
Br2(g)  2Br(g)
H° = 192.9 kJ/mol
Cl2(g)  2Cl(g)
H° = 243.4 kJ/mol
Br2(l) + Cl2(g)  2BrCl(g)
H° = 29.2 kJ/mol

A) 14.6 kJ/mol D) 438.0 kJ/mol
B) 203.5 kJ/mol E) 407.0 kJ/mol
C) 219.0 kJ/mol
Ans: C Category: Medium Section: 6.6

83. 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 minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 650. J/°C.)
A) –7.7°C B) 14.3°C C) 20.8°C D) 21.4°C E) 25.6°C
Ans: D Category: Difficult Section: 6.5

84. 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 minimum temperature reached by the solution? (The specific heat of water = 4.18 J/g·°C; the heat capacity of the calorimeter = 365. J/°C.)
A) 18.6°C B) 19.7°C C) 21.9°C D) 27.1°C E) 30.4°C
Ans: C Category: Difficult Section: 6.5

85. Aluminum oxide can be reduced to aluminum metal using carbon, the other reaction product being carbon monoxide. Determine the enthalpy change when 12.5 g of aluminum is produced by this method. [H°f(carbon monoxide) = –110.5 kJ/mol; H°f(aluminum oxide) = –1669.8 kJ/mol]
A) 310 kJ B) 361 kJ C) 697 kJ D) 725 kJ E) 1504 kJ
Ans: A Category: Difficult Section: 6.6

86. 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 8.50L 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? [H°f(NO) = 90.4 kJ/mol; H°f(NO2) = 33.85 kJ/mol; H°f(O3) = 142.2 kJ/mol]
A) –1690 kJ B) –167 kJ C) –97.6 kJ D) –69.2 kJ E) –19.7 kJ
Ans: D Category: Difficult Section: 6.6

87. Define specific heat.
Ans: The amount of heat required to raise the temperature of one gram of a substance by one degree Celsius.
Category: Easy Section: 6.5

88. How many grams of ethylene (C2H4) would have to be burned to produce 450 kJ of heat?
C2H4(g) + 3O2(g)  2CO2(g) + H2O(l) H°rxn = –1411 kJ/mol
Ans: 8.95 g
Category: Medium Section: 6.4

89. Calculate the enthalpy of reaction for H2(g) + C2H4(g)  C2H6(g).
[H°f(C2H4(g)) = 52.3 kJ/mol; H°f(C2H6(g)) = –84.7 kJ/mol]
Ans: –137 kJ/mol
Category: Medium Section: 6.6

90. The enthalpy of combustion of acetylene C2H2 is described by
C2H2(g) + (5/2)O2(g)  2CO2(g) + H2O(l) H°rxn= –1299 kJ/mol
Calculate the enthalpy of formation of acetylene, given the following enthalpies of formation
H°f[CO2(g)] = –393.5 kJ/mol
H°f[H2O(l)] = –285.8 kJ/mol
Ans: 226 kJ/mol
Category: Medium Section: 6.6

91. Given the following H° values,
H2(g) + O2(g)  H2O(l) H°f = –285.8 kJ/mol
H2O2(l)  H2(g) + O2(g) H°rxn = 187.6 kJ/mol
calculate H°rxn for the reaction H2O2(l)  H2O(l) + O2(g),
Ans: –98.2 kJ/mol
Category: Medium Section: 6.6

92. The heat of solution of calcium chloride CaCl2 is –82.8 kJ/mol, and the combined heats of hydration of 1.00 mole of gaseous calcium ions and 2.00 mole of gaseous chloride ions is –2327 kJ. What is the lattice energy of calcium chloride?
Ans: 2,244 kJ/mol
Category: Medium Section: 6.7

93. The heat of solution of NH4NO3 is 26.2 kJ/mol. Is heat evolved or absorbed when a solution of NH4NO3 is diluted by addition of more water?
Ans: Absorbed
Category: Easy Section: 6.7

94. A 26.2 g piece of copper metal is heated from 21.5°C to 201.6°C. Calculate the amount of heat absorbed by the metal. The specific heat of Cu is 0.385 J/g·°C.
Ans: 1,820 J
Category: Medium Section: 6.5

95. A 0.1946 g piece of magnesium metal is burned in a constant-volume calorimeter that has a heat capacity of 1349 J/°C. The calorimeter contains 500. g of water and the temperature rise is 1.40°C. Calculate the heat of combustion of magnesium metal in kJ/g, given that the specific heat of water = 4.184 J/g·°C.
Ans: 24.8 kJ/g
Category: Medium Section: 6.5

96. A 0.3423 g sample of pentane, C5H12, was burned in a bomb calorimeter. The temperature of the calorimeter and the 1.000 kg of water contained therein rose from 20.22°C to 22.82°C. The heat capacity of the calorimeter is 2.21 kJ/°C. The heat capacity of water = 4.184 J/g·°C. How much heat was given off during combustion of the sample of pentane?
Ans: 16.6 kJ
Category: Medium Section: 6.5

97. A 0.3423 g sample of pentane, C5H12, was burned in a bomb calorimeter. The temperature of the calorimeter and the 1.000 kg of water contained therein rose from 20.22°C to 22.82°C. The heat capacity of the calorimeter is 2.21 kJ/°C. The heat capacity of water = 4.184 J/g·°C. What is the heat of combustion, in kilojoules, per gram of pentane?
Ans: 48.6 kJ/g
Category: Medium Section: 6.5

98. The heat of combustion of propane, C3H8, 2220 kJ/mol. The specific heat of copper is 0.385 J/g°C. How many grams of propane must be burned to raise the temperature of a 10.0 kg block of copper from 25.0°C to 65.0°C, assuming none of the heat is lost to the surroundings
Ans: 3.06 g
Category: Medium Section: 6.5

99. The residential rate for natural gas is about $15 per thousand cubic foot. Burning one cubic foot of natural gas releases about 1080 kJ of heat. How much would it cost to heat the water in a 25,000 gallon swimming pool from 52°F to 78°F, assuming all of the heat from burning the natural gas went towards warming the water? (1 gal = 3.785 L; the specific heat of water = 4.184 J/g·°C)
Ans: $79
Category: Difficult Section: 6.5

100. The heat of neutralization of HCl by NaOH is H°rxn = –56.2 kJ/mol. How much heat is released when 125 mL of 1.750 M HCl is mixed with 195 mL of 0.667 M NaOH?
Ans: 7.31 kJ
Category: Difficult Section: 6.4

101. The heat released when one mole of water is formed from the elements is 1,198 kJ. An experiment was conducted that permitted water to form in this manner, and the heat was contained in 2.0 liters of water. The water temperature before the reaction was 34.5°C, and after the reaction it had risen to 52.0°C. How many moles of water were formed? (The specific heat of water is 4.184 J/g·°C.)
Ans: 0.12 mole
Category: Medium Section: 6.5

102. 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 as the temperature rises from 15.7°C to 95.7°C? (The specific heat of iron is 0.489 J/g·°C.)
Ans: 6,450 kJ
Category: Medium Section: 6.5

103. The value of H°rxn for the following reaction is –6535 kJ/mol.
2C6H6(l) + 15O2(g)  12CO2(g) + 6H2O(g)
How many kilojoules of heat will be evolved during the combustion of 16.0 g of C6H6(l)?
Ans: 669 kJ
Category: Medium Section: 6.4

104. What would be the standard enthalpy change for the reaction of 1.00 mole of H2(g) with 1.00 mole of Cl2(g) to produce 2.00 moles of HCl(g) at standard state conditions?
[H°f (HCl(g))= –92.3 kJ/mol]
Ans: –185 kJ
Category: Medium Section: 6.6

105. Calculate the heat released (kJ) in the reaction of 3.50 g of acetylene (C2H2) and excess hydrogen gas to form ethane gas:
C2H2(g) + 2H2(g)  C2H6(g)
Given:
2C2H2(g) + 5O2(g)  4CO2(g) + 2H2O(g) H = –2320 kJ/mol
2C2H6(g) + 7O2(g)  4CO2(g) + 6H2O(g) H = –3040 kJ/mol
2H2(g) + O2(g)  2H2O(g) H = –572 kJ/mol
Ans: 28.5 kJ
Category: difficult Section: 6.6

106. Calculate the heat released (kJ) in the reaction of 2.20 g of sulfur dioxide gas and excess oxygen gas to form sulfur trioxide gas:
2SO2(g) + O2(g)  2SO3(g)
Given:
S(s) + O2(g)  SO2(g) H = –299 kJ/mol
S(s) + 3/2O2(g)  SO3(g) H = –395 kJ/mol
Ans: 3.30 kJ
Category: difficult Section: 6.6

107. Find H°rxn for the reaction
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l).
[H°f (CH4(g)) = –74.8 kJ/mol; H°f (CO2(g)) = –393.5 kJ/mol; H°f (H2O(l)) = –285.5 kJ/mol]
Ans: -889.7 kJ/mol
Category: Medium Section: 6.6

108. Find H°rxn for the reaction
2Ag2S(s) + 2H2O(l)  4Ag(s) + 2H2S(g) + O2(g).
[H°f (Ag2S(s)) = –32.6 kJ/mol; H°f (H2S(g)) = –20.5 kJ/mol; H°f (H2O(l)) = –285.5 kJ/mol]
Ans: 595.2 kJ/mol
Category: Medium Section: 6.6

109. Find H°rxn for the reaction
2Na(s) + 2H2O(l)  2NaOH(aq) + 2H2(g).
[H°f (NaOH(aq)) = –426.8 kJ/mol; H°f (H2O(l)) = –285.5 kJ/mol]
Ans: –282.6 kJ
Category: Medium Section: 6.6

110. The specific heat of silver is 0.235 J/g·°C. How many joules of heat are required to heat a 75 g silver spoon from 20°C to 35°C?
Ans: 260 J
Category: Easy Section: 6.5

111. At body temperature 2,404 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?
Ans: 6.0 × 104 J
Category: Medium Section: 6.4

112. The combustion of one mole of benzene, C6H6, in oxygen liberates 3268 kJ of heat. The products of the reaction are carbon dioxide and water. How much heat is given off when 183 g of oxygen are reacted with excess benzene?
Ans: 2490 kJ
Category: Difficult Section: 6.4

113. A feverish student weighing 75 kilograms was immersed in 400. kg of water at 4.0°C to try to reduce the fever. The student’s body temperature dropped from 40.0°C to 37.0°C. Assuming the specific heat of the student to be 3.77 J/g·°C, what was the final temperature of the water?
Ans: 4.5°C
Category: Difficult Section: 6.5

114. The specific heats of water and iron are 4.184 and 0.444 J/g°C, respectively. When equal masses of water and iron both absorb the same amount of heat, the temperature increase of the water will be 5.42 times greater than that of the iron.
Ans: True Category: Medium Section: 6.5

115. Chemical reactions in a bomb calorimeter occur at constant pressure.
Ans: True Category: Easy Section: 6.5

116. If 2Mg(s) + O2(g)  2MgO(s), H° = –1203.6 kJ/mol.
For Mg(s) + (1/2)O2(g)  MgO(s), the enthalpy change is H = –601.8 kJ/mol.
Ans: True Category: Easy Section: 6.6

117. The heat capacity of 20.0 g of water is 83.7 J/°C.
Ans: True Category: Medium Section: 6.5

118. The work done on the surroundings by the expansion of a gas is w = –PV.
Ans: True Category: Easy Section: 6.3

119. The heat absorbed by a system at constant pressure is equal to E + PV.
Ans: True Category: Easy Section: 6.4

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