Chemistry Chapter 6
38. A 140.0-g sample of water at 25.0°C is mixed with 111.7 g of a certain metal at 100.0°C. After thermal equilibrium is established, the (final) temperature of the mixture is 29.6°C. What is the specific heat capacity of the metal, assuming it is constant over the temperature range concerned? A) 0.34 J/g°C B) 0.68 J/g°C C) 0.22 J/g°C D) 2.9 J/g°C E) none of these
A) 0.34 J/g°C
30. A 32.5 g piece of aluminum (which has a molar heat capacity of 24.03 J/°C·mol) is heated to 82.4°C and dropped into a calorimeter containing water (specific heat capacity of water is 4.18 J/g°C) initially at 22.3°C. The final temperature of the water is 24.2°C. Ignoring significant figures, calculate the mass of water in the calorimeter. A) 212 g B) 5.72 kg C) 6.42 g D) 1.68 kg E) none of these
A) 212 g
53. What is the enthalpy change when 49.4 mL of 0.430 M sulfuric acid reacts with 23.3 mL of 0.309 M potassium hydroxide? H2SO4(aq) + 2KOH(aq) → K2SO4(aq) + 2H2O(l) ΔH° = -111.6 kJ/mol A) -0.402 kJ B) -3.17 kJ C) -2.37 kJ D) -0.803 kJ E) -112 kJ
A) -0.402 kJ
80. This fossil fuel was formed from the remains of plants that were buried and exposed to high pressure and heat over time. A) coal B) natural gas C) diesel fuel D) propane E) gasoline
A) coal
64. Calculate ΔH° for the reaction C4H4(g) + 2H2(g) → C4H8(g), using the following data: ΔH°combustion for C4H4(g) = -2341 kJ/mol ΔH°combustion for H2(g) = -286 kJ/mol ΔH°combustion for C4H8(g) = -2755 kJ/mol A) -128 kJ B) -158 kJ C) 128 kJ D) 158 kJ E) none of these
B) -158 kJ
68. The heat of formation of Fe2O3(s) is -826.0 kJ/mol. Calculate the heat of the reaction when a 53.99-g sample of iron is reacted. A) -199.6 kJ B) -399.2 kJ C) -798.5 kJ D) -1597 kJ E) -2.230 × 104 kJ
B) -399.2 kJ
12. Calculate the work associated with the compression of a gas from 121.0 L to 80.0 L at a constant pressure of 13.1 atm. A) -537 L atm B) 537 L atm C) 3.13 L atm D) -3.13 L atm E) 101 L atm
B) 537 L atm
23. Which of the following properties is (are) intensive properties? I. mass II. temperature III. volume IV. concentration V. energy A) I, III, and V B) II only C) II and IV D) III and IV E) I and V
C) II and IV
54. How much heat is liberated at constant pressure when 2.35 g of potassium metal reacts with 5.68 mL of liquid iodine monochloride (d = 3.24 g/mL)? 2K(s) + ICl(l) → KCl(s) + KI(s) ΔH° = -740.71 kJ/mol A) 2.22 × 103 kJ B) 8.40 × 101 kJ C) 1.28 × 102 kJ D) 2.23 × 101 kJ E) 7.41 × 102 kJ
D) 2.23 × 101 kJ
49. The total volume of hydrogen gas needed to fill the Hindenburg was 2.11 × 108 L at 1.00 atm and 24.7°C. How much energy was evolved when it burned? A) 8.64 × 106 kJ B) 2.98 × 1010 kJ C) 3.02 × 104 kJ D) 2.47 × 109 kJ E) 4.94 × 109 kJ
D) 2.47 × 109 kJ
41. A chunk of lead at 91.6°C was added to 200.0 g of water at 15.5°C. The specific heat of lead is 0.129 J/g°C, and the specific heat of water is 4.18 J/g°C. When the temperature stabilized, the temperature of the mixture was 17.9°C. Assuming no heat was lost to the surroundings, what was the mass of lead added? A) 1.57 kg B) 170 g C) 204 g D) 211 g E) none of these
D) 211 g
44. A 4.4-g sample of Colorado oil shale is burned in a bomb calorimeter, which causes the temperature of the calorimeter to increase by 5.0°C. The calorimeter contains 1.00 kg of water (heat capacity of H2O = 4.184 J/g°C) and the heat capacity of the empty calorimeter is 0.10 kJ/°C. How much heat is released per gram of oil shale when it is burned? A) 21 kJ/g B) 42 kJ/g C) 0 kJ/g D) 4.9 kJ/g E) 0.21 kJ/g
D) 4.9 kJ/g
19. A state function does not depend on the system's past or future. True or False
True
60. Consider the following processes: 2A → (1/2)B + C ΔH1 = 5 kJ/mol (3/2)B + 4C → 2A + C + 3D ΔH2 = -15 kJ/mol E + 4A → C ΔH3 = 10 kJ/mol Calculate ΔH for: C → E + 3D A) 0 kJ/mol B) 10 kJ/mol C) -10 kJ/mol D) -20 kJ/mol E) 20 kJ/mol
C) -10 kJ/mol
22. Of energy, work, enthalpy, and heat, how many are state functions? A) 0 B) 1 C) 2 D) 3 E) 4
C) 2
63. At 25°C, the following heats of reaction are known: ΔH (kJ/mol) 2ClF + O2 → Cl2O + F2O 167.4 2ClF3 + 2O2 → Cl2O + 3F2O 341.4 2F2 + O2 → 2F2O -43.4 At the same temperature, calculate ΔH for the reaction: ClF + F2 → ClF3 A) -217.5 kJ/mol B) -130.2 kJ/mol C) +217.5 kJ/mol D) -108.7 kJ/mol E) none of these
D) -108.7 kJ/mol
8. Calculate the work for the expansion of CO2 from 1.0 to 4.7 liters against a pressure of 1.0 atm at constant temperature. A) 3.7 L·atm B) 4.7 L·atm C) 0 L·atm D) -3.7 L·atm E) -4.7 L·atm
D) -3.7 L·atm
1. A gas absorbs 0.0 J of heat and then performs 30.7 J of work. The change in internal energy of the gas is A) 61.4 J B) 30.7 J C) -61.4 J D) -30.7 J E) none of these
D) -30.7 J
62. Consider the following numbered processes: 1. A → 2B 2. B → C + D 3. E → 2D ΔH for the process A → 2C + E is A) ΔH1 + ΔH2 + ΔH3 B) ΔH1 + ΔH2 C) ΔH1 + ΔH2 - ΔH3 D) ΔH1 + 2ΔH2 - ΔH3 E) ΔH1 + 2ΔH2 + ΔH3
D) ΔH1 + 2ΔH2 - ΔH3
46. A bomb calorimeter has a heat capacity of 2.47 kJ/K. When a 0.109-g sample of ethylene (C2H4) was burned in this calorimeter, the temperature increased by 2.22 K. Calculate the energy of combustion for one mole of ethylene. A) -5.29 kJ/mol B) -50.3 kJ/mol C) -636 kJ/mol D) -0.269 kJ/mol E) -1.41 × 103 kJ/mol
E) -1.41 × 103 kJ/mol
71. Given: Cu2O(s) + O2(g) → 2CuO(s) ΔH° = -144 kJ Cu2O(s) → Cu(s) + CuO(s) ΔH° = +11 kJ Calculate the standard enthalpy of formation of CuO(s). A) -166 kJ B) -299 kJ C) +299 kJ D) +155 kJ E) -155 kJ
E) -155 kJ
75. For the reaction: AgI(s) + Br2(g) → AgBr(s) + I2(s), ΔH° = -54.0 kJ ΔHf° for AgBr(s) = -100.4 kJ/mol ΔHf° for Br2(g) = +30.9 kJ/mol The value of ΔHf° for AgI(s) is: A) -123.5 kJ/mol B) +77.3 kJ/mol C) +61.8 kJ/mol D) -77.3 kJ/mol E) -61.8 kJ/mol
E) -61.8 kJ/mol
28. How much heat is required to raise the temperature of a 5.75-g sample of iron (specific heat = 0.450 J/g°C) from 25.0°C to 79.8°C? A) 2.54 J B) 315 J C) 700 J D) 848 J E) 142 J
E) 142 J
79. The following statements concerning petroleum are all true except: A) It is a thick, dark liquid composed mostly of hydrocarbons. B) It must be separated into fractions (by boiling) in order to be used efficiently. C) Some of the commercial uses of petroleum fractions include gasoline and kerosene. D) It was probably formed from the remains of ancient marine organisms. E) All of its hydrocarbon chains contain the same number of carbon atoms.
E) All of its hydrocarbon chains contain the same number of carbon atoms.
20. When a system performs work on the surroundings, the work is reported with a negative sign.
True
21. In exothermic reaction, potential energy stored in chemical bonds is being converted to thermal energy via heat. True or False
True
57. The specific heat capacities of metals are relatively low. True or False
True
76. Using the information below, calculate ΔHf° for PbO(s) PbO(s) + CO(g) → Pb(s) + CO2(g) ΔH° = -131.4 kJ ΔHf° for CO2(g) = -393.5 kJ/mol ΔHf° for CO(g) = -110.5 kJ/mol A) -151.6 kJ/mol B) -283.0 kJ/mol C) +283.0 kJ/mol D) -372.6 kJ/mol E) +252.1 kJ/mol
A) -151.6 kJ/mol
67. Using the following thermochemical data, calculate ΔHf° of Tm2O3(s). 2TmCl3(s) + 3H2O(l) → Tm2O3(s) + 6HCl(g) ΔH° = 388.1 kJ/mol 2Tm(s) + 3Cl2(g) → 2TmCl3(s) ΔH° = -1973.2 kJ/mol 4HCl(g) + O2(g) → 2Cl2(g) + 2H2O(l) ΔH° = -202.4 kJ/mol A) -1888.7 kJ/mol B) -1787.5 kJ/mol C) 2563.7 kJ/mol D) -2158.9 kJ/mol E) 1382.7 kJ/mol
A) -1888.7 kJ/mol
50. CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g), ΔH = -434 kJ Based on the above reaction, what energy change occurs when 1.2 moles of methane (CH4) reacts? A) 5.2 × 105 J are released. B) 5.2 × 105 J are absorbed. C) 3.6 × 105 J are released. D) 3.6 × 105 J are absorbed. E) 4.4 × 105 J are released.
A) 5.2 × 105 J are released.
2. What is the kinetic energy of a 1.56-kg object moving at 94.0 km/hr? A) 5.32 × 102 kJ B) 6.89 × 103 kJ C) 5.32 × 10-4 kJ D) 1.06 × 103 kJ E) 2.04 × 101 kJ
A) 5.32 × 102 kJ
51. Given the equation S(s) + O2(g) → SO2(g), ΔH = -296 kJ, which of the following statement(s) is (are) true? I. The reaction is exothermic. II. When 0.500 mole sulfur is reacted, 148 kJ of energy is released. III. When 32.0 g of sulfur are burned, 2.96 × 105 J of energy is released. A) All are true. B) None is true. C) I and II are true. D) I and III are true. E) Only II is true.
A) All are true.
78. Consider the reaction: 2ClF3(g) + 2NH3(g) → N2(g) + 6HF(g) + Cl2(g) When calculating the ΔH°rxn, why is the ΔHf° for N2 not important? A) Because nitrogen is in its standard elemental state and no energy is needed for this product to exist. B) Because any element or compound in the gaseous state requires a negligible amount of energy to exist. C) Because the products are not included when calculating ΔH°rxn. D) Because nitrogen is in its elemental state and does not contribute to the reaction itself. E) Two of the above statements explain why N2 is not important when calculating ΔH°rxn.
A) Because nitrogen is in its standard elemental state and no energy is needed for this product to exist.
26. C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l), ΔH = -1.37 × 103 kJ For the combustion of ethyl alcohol as described in the above equation, which of the following is true? I. The reaction is exothermic. II. The enthalpy change would be different if gaseous water was produced. III. The reaction is not an oxidation-reduction one. IV. The products of the reaction occupy a larger volume than the reactants. A) I, II B) I, II, III C) I, III, IV D) III, IV E) only I
A) I, II
29. Two metals of equal mass with different heat capacities are subjected to the same amount of heat. Which undergoes the smallest change in temperature? A) The metal with the higher heat capacity. B) The metal with the lower heat capacity. C) Both undergo the same change in temperature. D) You need to know the initial temperatures of the metals. E) You need to know which metals you have.
A) The metal with the higher heat capacity.
11. Calculate the work associated with the expansion of a gas from 42.0 L to 79.0 L at a constant pressure of 14.0 atm. A) 518 L·atm B) -518 L·atm C) -1.11 × 103 L·atm D) 588 L·atm E) 1.11 × 103 L·atm
B) -518 L·atm
43. What is the specific heat capacity of silver if it requires 86.3 J to raise the temperature of 15 grams of silver by 25°C? A) 4.3 J/g°C B) 0.23 J/g°C C) 0.14 J/g°C D) 0.60 J/g°C E) none of these
B) 0.23 J/g°C
40. Exactly 123.7 J will raise the temperature of 10.0 g of a metal from 25.0°C to 60.0°C. What is the specific heat capacity of the metal? A) 2.83 J/g°C B) 0.353 J/g°C C) 24.9 J/g°C D) 29.6 J/g°C E) none of these
B) 0.353 J/g°C
34. 30.0 mL of pure water at 282 K is mixed with 50.0 mL of pure water at 306 K. What is the final temperature of the mixture? A) 294 K B) 297 K C) 342 K D) 588 K E) 24 K
B) 297 K
56. The heat of combustion of benzene, C6H6, is -41.74 kJ/g. Combustion of 2.82 g of benzene causes a temperature rise of 3.29°C in a certain bomb calorimeter. What is the heat capacity of this bomb calorimeter? A) 387 kJ/°C B) 35.8 kJ/°C C) 0.222 kJ/°C D) 5.96 kJ/°C E) 118 kJ/°C
B) 35.8 kJ/°C
33. The enthalpy of fusion of ice is 6.020 kJ/mol. The heat capacity of liquid water is 75.4 J/mol·°C. What is the smallest number of ice cubes at 0°C, each containing one mole of water, necessary to cool 500 g of liquid water initially at 20°C to 0°C? A) 1 B) 7 C) 14 D) 15 E) 126
B) 7
7.One mole of an ideal gas is expanded from a volume of 1.00 liter to a volume of 8.93 liters against a constant external pressure of 1.00 atm. How much work (in joules) is performed on the surroundings? Ignore significant figures for this problem. (T = 300 K; 1 L·atm = 101.3 J) A) 402 J B) 803 J C) 2.41 × 103 J D) 905 J E) none of these
B) 803 J
42. On a cold winter day, a steel metal fence post feels colder than a wooden fence post of identical size because: A) The specific heat capacity of steel is higher than the specific heat capacity of wood. B) The specific heat capacity of steel is lower than the specific heat capacity of wood. C) Steel has the ability to resist a temperature change better than wood. D) The mass of steel is less than wood so it loses heat faster. E) Two of the above statements are true.
B) The specific heat capacity of steel is lower than the specific heat capacity of wood.
For the reaction H2O(l) → H2O(g) at 298 K and 1.0 atm, ΔH is more positive than ΔE by 2.5 kJ/mol. This quantity of energy can be considered to be A) the heat flow required to maintain a constant temperature B) the work done in pushing back the atmosphere C) the difference in the H-O bond energy in H2O(l) compared to H2O(g) D) the value of ΔH itself E) none of these
B) the work done in pushing back the atmosphere
61. Consider the following processes: ΔH (kJ/mol) 3B → 2C + D -125 (1/2)A →B 150 E + A → D 350 Calculate ΔH for: B → E + 2C A) 325 kJ/mol B) 525 kJ/mol C) -175 kJ/mol D) -325 kJ/mol E) none of these
C) -175 kJ/mol
When 0.236 mol of a weak base (A-) is reacted with excess HCl, 6.91 kJ of energy is released as heat. What is ΔH for this reaction per mole of A- consumed? A) -34.2 kJ B) -59.4 kJ C) -29.3 kJ D) 34.2 kJ E) 29.3 kJ
C) -29.3 kJ
9. A fuel-air mixture is placed in a cylinder fitted with a piston. The original volume is 0.310-L. When the mixture is ignited, gases are produced and 935 J of energy is released. To what volume will the gases expand against a constant pressure of 635 mmHg, if all the energy released is converted to work to push the piston? A) 10.7 L B) 8.02 L C) 11.4 L D) 11.0 L E) 1.78 L
C) 11.4 L
72. Using the following data, calculate the standard heat of formation of the compound ICl in kJ/mol: ΔH° (kJ/mol) Cl2(g) → 2Cl(g) 242.3 I2(g) → 2I(g) 151.0 ICl(g) → I(g) + Cl(g) 211.3 I2(s) → I2(g) 62.8 A) -211 kJ/mol B) -14.6 kJ/mol C) 16.8 kJ/mol D) 245 kJ/mol E) 439 kJ/mol
C) 16.8 kJ/mol
73. The heat combustion of acetylene, C2H2(g), at 25°C is -1299 kJ/mol. At this temperature, ΔHf° values for CO2(g) and H2O(l) are -393 and -286 kJ/mol, respectively. Calculate ΔHf° for acetylene. A) 2376 kJ/mol B) 625 kJ/mol C) 227 kJ/mol D) -625 kJ/mol E) -227 kJ/mol
C) 227 kJ/mol
48. The ΔH value for the reaction is -90.8 kJ. How much heat is released when 66.9 g Hg is reacted with oxygen? A) 0.333 kJ B) 6.07 × 103 kJ C) 30.3 kJ D) 90.8 kJ E) none of these
C) 30.3 kJ
32. You take 295.5 g of a solid at 30.0°C and let it melt in 425 g of water. The water temperature decreases from 85.1°C to 30.0°C. Calculate the heat of fusion of this solid. A) 160 J/g B) 166 J/g C) 331 J/g D) 721 J/g E) cannot solve without the heat capacity of the solid
C) 331 J/g
47. Consider the reaction: When a 21.1-g sample of ethyl alcohol (molar mass = 46.07 g/mol) is burned, how much energy is released as heat? A) 0.458 kJ B) 0.627 kJ C) 6.27 × 102 kJ D) 2.89 × 104 kJ E) 2.18 kJ
C) 6.27 × 102 kJ
66. Using the following thermochemical data: 2Cr(s) + 6HF(g) → 2CrF3(s) + 3H2(g) ΔH° = -691.4 kJ/mol 2Cr(s) + 6HCl(g) → 2CrCl3(s) + 3H2(g) ΔH° = -559.2 kJ/mol calculate ΔH° for the following reaction: CrF3(s) + 3HCl(g) → CrCl3(s) + 3HF(g) A) -1250.6 kJ/mol B) 132.2 kJ/mol C) 66.1 kJ/mol D) 264.4 kJ/mol E) -625.3 kJ/mol
C) 66.1 kJ/mol
25. Which one of the following statements is false? A) The change in internal energy, ΔE, for a process is equal to the amount of heat absorbed at constant volume, qv. B) The change in enthalpy, ΔH, for a process is equal to the amount of heat absorbed at constant pressure, qp. C) A bomb calorimeter measures ΔH directly. D) If qp for a process is negative, the process is exothermic. E) The freezing of water is an example of an exothermic reaction.
C) A bomb calorimeter measures ΔH directly.
Choose the correct equation for the standard enthalpy of formation of CO(g), where ΔHf° for CO = -110.5 kJ/mol (gr indicates graphite). A) 2C(gr) + O2(g) → 2CO(g), ΔH° = -110.5 kJ B) C(gr) + O(g) → CO(g), ΔH° = -110.5 kJ C) C(gr) + O2(g) → CO(g), ΔH° = -110.5 kJ D) C(gr) + CO2(g) → 2CO(g), ΔH° = -110.5 kJ E) CO(g) → C(gr) + O(g), ΔH° = -110.5 kJ
C) C(gr) + O2(g) → CO(g), ΔH° = -110.5 kJ
69. Which of the following does not have a standard enthalpy of formation equal to zero at 25°C and 1.0 atm? A) F2(g) B) Al(s) C) H2O(l) D) H2(g) E) They all have a standard enthalpy equal to zero.
C) H2O(l)
13. According to the first law of thermodynamics, the energy of the universe is constant. Does this mean that ΔE is always equal to zero? A) Yes, ΔE = 0 at all times, which is why q = -w. B) No, ΔE does not always equal zero, but this is only due to factors like friction and heat. C) No, ΔE does not always equal zero because it refers to the system's internal energy, which is affected by heat and work. D) No, ΔE never equals zero because work is always being done on the system or by the system. E) No, ΔE never equals zero because energy is always flowing between the system and surroundings.
C) No, ΔE does not always equal zero because it refers to the system's internal energy, which is affected by heat and work.
36. In the lab, you mix two solutions (each originally at the same temperature) and the temperature of the resulting solution decreases. Which of the following is true? A) The chemical reaction is releasing energy. B) The energy released is equal to s × m × ΔT. C) The chemical reaction is absorbing energy. D) The chemical reaction is exothermic. E) More than one of these.
C) The chemical reaction is absorbing energy.
5. Which of the following statements is correct? A) The internal energy of a system increases when more work is done by the system than heat was flowing into the system. B) The internal energy of a system decreases when work is done on the system and heat is flowing into the system. C) The system does work on the surroundings when an ideal gas expands against a constant external pressure. D) All statements are true. E) All statements are false.
C) The system does work on the surroundings when an ideal gas expands against a constant external pressure.
3. Which of the following statements correctly describes the signs of q and w for the following exothermic process at P = 1 atm and T = 370 K? H2O(g) → H2O(l) A) q and w are negative. B) q is positive, w is negative. C) q is negative, w is positive. D) q and w are both positive. E) q and w are both zero.
C) q is negative, w is positive.
37. What is the specific heat capacity of a metal if it requires 178.1 J to change the temperature of 15.0 g of the metal from 25.00°C to 32.00°C? A) 0.590 J/g°C B) 11.9 J/g°C C) 25.4 J/g°C D) 1.70 J/g°C E) 283 J/g°C
D) 1.70 J/g°C
77. For which of the following reaction(s) is the enthalpy change for the reaction not equal to ΔHf° of the product? I. 2H(g) → H2(g) II. H2(g) + O2(g) → H2O2(l) III. H2O(l) + O(g) → H2O2(l) A) I B) II C) III D) I and III E) II and III
D) I and III
59. Which of the following statements is/are true? I. q (heat) is a state function because ΔH is a state function and q = ΔH. II. When 50.0 g of aluminum at 20.0°C is placed in 50.0 mL of water at 30.0°C, the H2O will undergo a smaller temperature change than the aluminum. (The density of H2O = 1.0 g/mL, specific heat capacity of H2O = 4.18 J/g°C, specific heat capacity of aluminum = 0.89 J/g°C) III. When a gas is compressed, the work is negative since the surroundings are doing work on the system and energy flows out of the system. IV. For the reaction (at constant pressure) 2N2(g) + 5O2(g) → 2N2O5(g), the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps. A) I, II, IV B) II, III C) II, III, IV D) II, IV E) All of the above statements are true.
D) II, IV
45. If a student performs an endothermic reaction in a calorimeter, how does the calculated value of ΔH differ from the actual value if the heat exchanged with the calorimeter is not taken into account? A) ΔHcalc would be more negative because the calorimeter always absorbs heat from the reaction. B) ΔHcalc would be less negative because the calorimeter would absorb heat from the reaction. C) ΔHcalc would be more positive because the reaction absorbs heat from the calorimeter. D) ΔHcalc would be less positive because the reaction absorbs heat from the calorimeter. E) ΔHcalc would equal the actual value because the calorimeter does not absorb heat.
D) ΔHcalc would be less positive because the reaction absorbs heat from the calorimeter.
70. Given the following two reactions at 298 K and 1 atm, which of the statements is true? 1. N2(g) + O2(g) → 2NO(g) ΔH1 2. NO(g) + O2(g) → NO2(g) ΔH2 A) ΔHf° for NO2(g) = ΔH2 B) ΔHf° for NO(g) = ΔH1 C) ΔHf° = ΔH2 D) ΔHf° for NO2(g) = ΔH2 + ΔH1 E) none of these
D) ΔHf° for NO2(g) = ΔH2 + ΔH1
35. Consider the reaction H2(g) + O2(g) → H2O(l) ΔH° = -286 kJ Which of the following is true? A) The reaction is exothermic. B) The reaction is endothermic. C) The enthalpy of the products is less than that of the reactants. D) Heat is absorbed by the system. E) Both A and C are true.
E) Both A and C are true.
27. Consider the reaction: C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l); ΔH = -1.37 × 103 kJ Consider the following propositions: I. The reaction is endothermic II. The reaction is exothermic. III. The enthalpy term would be different if the water formed was gaseous. Which of these propositions is (are) true? A) I B) II C) III D) I, II E) II, III
E) II, III
55. Consider the following specific heats of metals. Metal Specific Heat Zinc 0.387 J/(g°C) Magnesium 1.02 J/(g°C) Iron 0.450 J/(g°C) Silver 0.237 J/(g°C) Lead 0.127 J/(g°C) If the same amount of heat is added to 25.0 g of each of the metals, which are all at the same initial temperature, which metal will have the highest temperature? A) Zinc B) Magnesium C) Iron D) Silver E) Lead
E) Lead
10. Which statement is true of a process in which one mole of a gas is expanded from state A to state B? A) When the gas expands from state A to state B, the surroundings are doing work on the system. B) The amount of work done in the process must be the same, regardless of the path. C) It is not possible to have more than one path for a change of state. D) The final volume of the gas will depend on the path taken. E) The amount of heat released in the process will depend on the path taken.
E) The amount of heat released in the process will depend on the path taken.
39. If 5.0 kJ of energy is added to a 15.5-g sample of water at 10.°C, the water is A) boiling B) completely vaporized C) frozen solid D) decomposed E) still a liquid
E) still a liquid
18. A property that is independent of the pathway is called an intensive property. True or False?
False
58. The change in enthalpy can always be thought of as equal to energy flow as heat. True or False
False
65. Given the heats of the following reactions: ΔH°(kJ) I. P4(s) + 6Cl2(g) → 4PCl3(g) -1225.6 II. P4(s) + 5O2(g) → P4O10(s) -2967.3 III. PCl3(g) + Cl2(g) → PCl5(g) -84.2 IV. PCl3(g) + O2(g) → Cl3PO(g) -285.7 Calculate the value of ΔH° for the reaction below: P4O10(s) + 6PCl5(g) → 10Cl3PO(g) A) -110.5 kJ B) -610.1 kJ C) -2682.2 kJ D) -7555.0 kJ E) None of these is within 5% of the correct answer.
B) -610.1 kJ
31. A 45.9 g sample of a metal is heated to 95.2°C and then placed in a calorimeter containing 120.0 g of water (c = 4.18 J/g°C) at 21.6°C. The final temperature of the water is 24.5°C. Which metal was used? A) Aluminum (c = 0.89 J/g°C) B) Iron (c = 0.45 J/g°C) C) Copper (c = 0.20 J/g°C) D) Lead (c = 0.14 J/g°C) E) none of these
B) Iron (c = 0.45 J/g°C)
14. What is true about the value of q? A) It is greater than zero. B) It is equal to zero. C) It is less than zero. D) More information is needed. E) None of these.
B) It is equal to zero.
15. What is true about the value of w? A) It is greater than zero. B) It is equal to zero. C) It is less than zero. D) More information is needed. E) None of these.
B) It is equal to zero.
16. What is true about the value of ΔE? A) It is greater than zero. B) It is equal to zero. C) It is less than zero. D) More information is needed. E) None of these.
B) It is equal to zero.
17. What is true about the value of ΔH? A) It is greater than zero. B) It is equal to zero. C) It is less than zero. D) More information is needed. E) None of these.
B) It is equal to zero.
6. For a particular process q = -17 kJ and w = 21 kJ. Which of the following statements is false? A) Heat flows from the system to the surroundings. B) The system does work on the surroundings. C) ΔE = +4 kJ D) The process is exothermic. E) None of the above is false.
B) The system does work on the surroundings.
4. For a particular process q = 20 kJ and w = 15 kJ. Which of the following statements is true? A) Heat flows from the system to the surroundings. B) The system does work on the surroundings. C) ΔE = 35 kJ D) All of the above are true. E) None of the above are true.
C) ΔE = 35 kJ
