Chapter 6 – Thermochemistry
1. The energy associated with the separation of two electrical charges is called _____.
A)
heat
B)
internal energy
C)
temperature
D)
kinetic energy
E)
potential energy
2. The energy associated with the motion of a speeding bullet is called _____.
A)
heat
B)
internal energy
C)
temperature
D)
kinetic energy
E)
potential energy
3. The air whipped up by a tornado possesses what type(s) of energy?
A)
potential energy only
B)
internal energy only
C)
kinetic energy only
D)
kinetic energy, potential energy, and internal energy
E)
kinetic energy and potential energy only
4. The internal energy of a substance is defined as
A)
the potential energy of all particles which make up the substance.
B)
the kinetic energy of all particles which make up the substance.
C)
the sum of the potential and kinetic energy of all particles which make up the
substance.
D)
the thermal energy of all particles which make up the substance.
E)
the chemical energy of all particles which make up the substance.
5. What is the kinetic energy of a 2000-lb car traveling at 48 miles per hour?
(1 lb = 0.4536 kg, 1 mi = 1.609 km)
A)
2.1 10–7 J
B)
1.0 106 J
C)
3.5 1019 J
D)
2.1 105 J
E)
3.1 10–8 J
6. Calculate U of a gas for a process in which the gas absorbs 9 J of heat and does 25 J of
work by expanding.
A)
16 J
B)
34 J
C)
–34 J
D)
0, because U is a state function
E)
–16 J
7. Which of the following is an endothermic process?
A)
work is done by the system on the surroundings
B)
heat energy flows from the system to the surroundings
C)
work is done on the system by the surroundings
D)
heat energy is evolved by the system
E)
none of the above
8. Which of the following does not result in a change in the internal energy of the system?
A)
work is done on the system
B)
work is done on the surroundings
C)
heat flows into the system
D)
heat flows to the surroundings
E)
none of the above
9. Which of the following statements about heat is false?
A)
If heat flows into a system, the extra energy of the system appears in the form of
internal energy.
B)
A hot object possesses more heat than a cold object.
C)
If the system and surroundings are in thermal equilibrium, there is no heat flow
between them.
D)
A process in which heat flows out of a system is said to be exothermic.
E)
Heat is a form of energy flow.
10. If q = –91 kJ for a certain process, that process
A)
requires a catalyst.
B)
is exothermic.
C)
occurs rapidly.
D)
is endothermic.
E)
cannot occur.
11. If q = 28 kJ and w = 85 kJ for a certain process, that process
A)
requires a catalyst.
B)
is endothermic.
C)
occurs slowly.
D)
is exothermic.
E)
cannot occur.
12. What is the change in internal energy of the system (U) if 10 kJ of heat energy is absorbed
by the system and 70 kJ of work is done by the system for a certain process?
A)
–60 kJ
B)
80 kJ
C)
10 kJ
D)
60 kJ
E)
–80 kJ
13. At constant pressure, the sign of q for the process CO2(s) → CO2(g) is expected to be
A)
positive, and the process is exothermic.
B)
negative, and the process is exothermic.
C)
impossible to predict.
D)
positive, and the process is endothermic.
E)
negative, and the process is endothermic.
14. At constant pressure, the sign of q for the process H2O(l) → H2O(s) is expected to be
A)
positive, and the process is exothermic.
B)
negative, and the process is endothermic.
C)
impossible to predict.
D)
negative, and the process is exothermic.
E)
positive, and the process is endothermic.
15. Which of the following statements is not true for an exothermic reaction?
A)
The products have a higher heat content than the reactants.
B)
The temperature of the reaction system increases.
C)
The temperature of the surroundings increases.
D)
Heat passes from the reaction system to the surroundings.
E)
The enthalpy change for the reaction is negative.
16. H2 and F2 react according to the following equation, forming HF.
H2(g) + F2(g) → 2HF(g); H° = –271 kJ
If H2(g) and F2(g) were mixed in a thermally insulated vessel, the reaction that occurred
would be
A)
endothermic, and the temperature of the reaction system would fall.
B)
We could not tell unless the original and final temperatures were given.
C)
exothermic, and the temperature of the reaction system would fall.
D)
exothermic, and the temperature of the reaction system would rise.
E)
endothermic, and the temperature of the reaction system would rise.
Test Bank General Chemistry, 10th edition 5
17. Which of the following statements is incorrect?
A)
Internal energy is a state function.
B)
The value of q is positive when heat flows into a system from the surroundings.
C)
The value of q is positive in an endothermic process.
D)
Heat flows from a system into the surroundings in an endothermic process.
E)
Enthalpy is a state function.
18. Which of the following statements about enthalpy is false?
A)
Enthalpy is a state function.
B)
At constant pressure, the enthalpy change is equal to the heat absorbed or released.
C)
Enthalpy is an extensive property.
D)
The change in enthalpy of a process cannot be negative.
E)
The SI unit of enthalpy is J.
19. The phrase “the heat absorbed or released by a system undergoing a physical or chemical
change at constant pressure” is
A)
the change in enthalpy of the system.
B)
the change in internal energy of the system.
C)
the definition of a state function.
D)
the temperature change of the system.
E)
a statement of Hess’s law.
20. Which of the following statements is true concerning the decomposition of liquid water to
form hydrogen gas and oxygen gas?
2H2O(l) → 2H2(g) + O2(g)
A)
H is greater than U because the pressure is constant.
B)
H is less than U because of the pressure–volume work done by the gaseous
products.
C)
H is less than U because the atmosphere does pressure–volume work on the
gaseous products.
D)
H equals U because both are state functions.
E)
H is greater than U because of the pressure–volume work done by the gaseous
products.
Test Bank General Chemistry, 10th edition 6
21. Under conditions of constant pressure, for which of the following reactions is the magnitude
of pressure-volume work going to be greatest?
A)
BaO(s) + SO3(g) → BaSO4(s)
B)
2NO(g) + O2(g) → 2NO2(g)
C)
2H2O2(l) → 2H2O(l) + O2(g)
D)
2KClO3(s) → 2KCl(s) + 3O2(g)
E)
H2(g) + Cl2(g) → 2HCl(g)
22. Under conditions of constant pressure, for which of the following reactions is the magnitude
of pressure-volume work going to be smallest?
A)
BaO(s) + SO3(g) → BaSO4(s)
B)
2NO(g) + O2(g) → 2NO2(g)
C)
2H2O2(l) → 2H2O(l) + O2(g)
D)
2KClO3(s) → 2KCl(s) + 3O2(g)
E)
H2(g) + Cl2(g) → 2HCl(g)
23. Which of the following sentences accurately describes the thermochemical equation given
below?
2Ag(s) + F2(g) → 2AgF(s); H = –409.2 kJ
A)
If 2 mol of silver metal react with 1 mol of fluorine gas at constant volume, 2 mol
of solid sodium fluoride is produced and 409.2 kJ of heat is consumed.
B)
If 2 atoms of silver metal react with 1 molecule of fluorine gas at constant
pressure, 2 formula units of solid sodium fluoride are produced and 409.2 kJ of
heat is released.
C)
If 2 atoms of silver metal react with 1 molecule of fluorine gas at constant
pressure, 2 formula units of solid sodium fluoride are produced and 409.2 kJ of
heat is consumed.
D)
If 2 mol of silver metal react with 1 mol of fluorine gas at constant pressure, 2 mol
of solid sodium fluoride is produced and 409.2 kJ of heat is consumed.
E)
If 2 mol of silver metal react with 1 mol of fluorine gas at constant pressure, 2 mol
of solid sodium fluoride is produced and 409.2 kJ of heat is released.
Test Bank General Chemistry, 10th edition 7
24. Which of the following statements is incorrect concerning the thermochemical equation
below?
2SO3(g) → 2SO2(g) + O2(g); H° = 198 kJ
A)
The enthalpy of the reactants exceeds that of the products.
B)
The reaction is endothermic.
C)
For the reaction 2SO2(g) + O2(g) → 2SO3(g), H° = –198 kJ.
D)
The external pressure is 1 atm.
E)
For every mole of SO3(g) consumed, 99 kJ of heat at constant pressure is
consumed as well.
25. In a certain experiment, 0.1000 mol of hydrogen gas reacted with 0.1000 mol of solid iodine
at a constant 1 atm pressure, producing 0.2000 mol of solid hydrogen iodide and absorbing
5.272 kJ of heat in the process. Which of the following thermochemical equations correctly
describes this experiment?
A)
H2(g) + I2(s) → 2HI(s); H° = –52.72 kJ
B)
H2(g) + I2(s) → 2HI(s); H° = 5.272 kJ
C)
H2(g) + I2(s) → 2HI(s); H° = –5.272 kJ
D)
H2(g) + I2(s) → 2HI(s); H° = 10.54 kJ
E)
H2(g) + I2(s) → 2HI(s); H° = 52.72 kJ
26. Given:
4AlCl3(s) + 3O2(g) → 2Al2O3(s) + 6Cl2(g); H = –529.0 kJ
determine H for the following thermochemical equation.
Cl2(g) + Al2O3(s) → AlCl3(s) + O2(g)
A)
+264.5 kJ
B)
+529.0 kJ
C)
+88.2 kJ
D)
+176.3 kJ
E)
–176.3 kJ
Test Bank General Chemistry, 10th edition 8
27. Given the thermochemical equation
2Al(s) + O2(g) → Al2O3(s); H = –1676 kJ
find H for the following reaction.
2Al2O3(s) → 4Al(s) + 3O2(g)
A)
838 kJ
B)
1676 kJ
C)
–1676 kJ
D)
3352 kJ
E)
–838 kJ
28. Given:
what is H for the following thermochemical equation?
A)
986.9 kJ
B)
-986.9 kJ
C)
–139 MJ
D)
–2320 kJ
E)
–38.7 kJ
29. Which of the following statements is false concerning the reaction of hydrogen gas and
oxygen gas given below?
H2(g) + O2(g) → H2O(l); H = –285.8 kJ
A)
Per mole of O2, the change in enthalpy is –571.6 kJ.
B)
The value –571.6 kJ pertains to 1 mol of liquid water.
C)
If the equation is reversed, H becomes +285.8 kJ.
D)
If the equation is multiplied by 2, H becomes –571.6 kJ.
E)
For the reaction H2(g) + O2(g) → H2O(g), H is not equal to –285.8 kJ.
Test Bank General Chemistry, 10th edition 9
30. What is the change in enthalpy when 4.00 mol of sulfur trioxide decomposes to sulfur
dioxide and oxygen gas?
2SO2(g) + O2(g) → 2SO3(g); H° = 198 kJ
A)
396 kJ
B)
–198 kJ
C)
–396 kJ
D)
198 kJ
E)
792 kJ
31. What is the change in enthalpy at 25°C and 1 atm for the production of 9.00 mol SnO(s)?
Sn(s) + SnO2(s) → 2SnO(s); H° = 16.2 kJ
A)
–72.9 kJ
B)
–16.2 kJ
C)
16.2 kJ
D)
1.80 kJ
E)
72.9 kJ
32. What is the change in enthalpy at 25°C and 1 atm for the reaction of 5.00 mol of elemental
iron with excess oxygen gas?
4Fe(s) + 3O2(g) → 2Fe2O3(s); H° = –1651 kJ
A)
−1651 kJ
B)
2752 kJ
C)
2064 kJ
D)
–2064 kJ
E)
−412.8 kJ
Test Bank General Chemistry, 10th edition 10
33. What is the quantity of heat evolved at constant pressure when 60.3 g H2O(l) is formed from
the combustion of H2(g) and O2(g)?
H2(g) + O2(g) → H2O(l); H° = –285.8 kJ
A)
1.17 10–2 kJ
B)
285.8 kJ
C)
1.72 104 kJ
D)
85.4 kJ
E)
9.57 102 kJ
34. What quantity, in moles, of hydrogen is consumed when 676.8 kJ of energy is evolved from
the combustion of a mixture of H2(g) and O2(g)?
H2(g) + O2(g) → H2O(l); H° = –285.8 kJ
A)
2.368 mol
B)
1.184 mol
C)
0.4223 mol
D)
3.368 mol
E)
1.368 mol
35. What mass of hydrogen is consumed when 587.9 kJ of energy is evolved from the
combustion of a mixture of H2(g) and O2(g)?
H2(g) + O2(g) → H2O(l); H° = –285.8 kJ
A)
4.147 g
B)
2.073 g
C)
0.2412 g
D)
6.162 g
E)
2.131 g
Test Bank General Chemistry, 10th edition 11
36. According to the following thermochemical equation, if 951.1 g of NO2 is produced, how
much heat is released at constant pressure?
2NO(g) + O2(g) → 2NO2(g); H° = –114.4 kJ
A)
114.4 kJ
B)
1.183 103 kJ
C)
2.365 103 kJ
D)
5.534 kJ
E)
1.088 105 kJ
37. Consider the following thermochemical equation:
N2(g) + 2O2(g) → 2NO2(g); H° = 66.2 kJ
From this equation, we may conclude that 66.2 kJ is the quantity of heat that is
A)
gained from the surroundings when 1 mol of NO2 is formed at constant pressure.
B)
lost to the surroundings when 1 mol of NO2 is formed at constant pressure.
C)
gained from the surroundings when 2 mol of NO2 is formed at constant pressure.
D)
lost to the surroundings when 2 mol of NO2 is formed at constant pressure.
E)
lost to the surroundings when 1 mol of O2 is consumed at constant pressure.
38. How much heat is liberated at constant pressure if 0.834 g of calcium carbonate reacts with
48.9 mL of 0.668 M hydrochloric acid?
CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g); H° = –15.2 kJ
A)
–0.127 kJ
B)
–0.375 kJ
C)
–12.7 kJ
D)
–0.248 kJ
E)
–10.2 kJ
39. When 34.1 g of lead reacts with 6.81 L of oxygen gas, measured at 1.00 atm and 25.0°C,
36.1 kJ of heat is released at constant pressure. What is H° for this reaction?
(R = 0.0821 L • atm/(K • mol))
2Pb(s) + O2(g) → 2PbO(s)
A)
–4.39 102 kJ
B)
–5.94 101 kJ
C)
–3.61 101 kJ
D)
–2.19 102 kJ
E)
–1.30 102 kJ
40. How much heat is evolved upon the complete oxidation of 9.118 g of aluminum at 25°C and
1 atm pressure? ( for Al2O3 is –1676 kJ/mol.)
4Al(s) + 3O2(g) → 2Al2O3(s)
A)
1.528 104 kJ
B)
566.4 kJ
C)
1133 kJ
D)
283.2 kJ
E)
141.6 kJ
Test Bank General Chemistry, 10th edition 13
41. The reaction of iron with hydrochloric acid is represented by the following thermochemical
equation.
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g); H° = –87.9 kJ
How much heat is liberated at constant pressure if 0.358 g of iron reacts with 34.1 mL of
0.588 M HCl?
A)
4.09 kJ
B)
31.5 kJ
C)
0.563 kJ
D)
0.881 kJ
E)
87.9 kJ
42. At constant pressure and 25C, what is H for the following reaction
2C2H6(g) + 7O2(g) → 4CO2(g) + H2O(l)
if the complete consumption of 11.3 g of C2H6 liberates –586.3 kJ of heat energy?
A)
–3120 kJ
B)
–1560 kJ
C)
–441 kJ
D)
–222 kJ
E)
–786 kJ
43. The reaction of iron with hydrochloric acid is represented by the following thermochemical
equation.
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g); H° = –87.9 kJ
If, in a particular experiment, 7.36 kJ of heat was released at constant pressure, what volume
of H2(g), measured at STP, was produced? (R = 0.0821 L • atm/(K • mol))
A)
2.92 102 L
B)
2.05 L
C)
22.4 L
D)
2.68 102 L
E)
1.88 L
Test Bank General Chemistry, 10th edition 14
44. The reaction of iron with hydrochloric acid is represented by the following thermochemical
equation.
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g); H° = –87.9 kJ
In which of the following experiments would the temperature rise the most?
A)
2.2 g of Fe added to 1.0 L of 0.03 M HCl
B)
1.1 g of Fe added to 1.0 L of 0.02 M HCl
C)
4.5 g of Fe added to 1.0 L of 0.03 M HCl
D)
1.1 g of Fe added to 1.0 L of 0.04 M HCl
E)
0.56 g of Fe added to 1.0 L of 0.02 M HCl
45. How much heat is released at constant pressure if 16.9 mL of 0.694 M silver nitrate is mixed
with 79.7 mL of 0.372 M potassium chloride?
AgNO3(aq) + KCl(aq) → AgCl(s) + KNO3(aq); H° = –65.5 kJ
A)
–0.768 kJ
B)
–24.4 kJ
C)
–1.94 kJ
D)
–45.5 kJ
E)
–2.71 kJ
46. How much heat is liberated at constant pressure when 58.5 g of calcium oxide reacts with
83.9 L of carbon dioxide gas, measured at 1.00 atm pressure and 25.0°C?
(R = 0.0821 L • atm/(K • mol))
CaO(s) + CO2(g) → CaCO3(s); H° = –178.3 kJ
A)
–6.11 102 kJ
B)
–1.04 104 kJ
C)
–7.97 102 kJ
D)
–1.86 102 kJ
E)
–1.50 104 kJ
47. When 32.4 mL of liquid benzene (C6H6, d = 0.879 g/mL) reacts with 81.6 L of oxygen gas,
measured at 1.00 atm pressure and 25°C, 1.19 103 kJ of heat is released at constant
pressure. What is H° for the following reaction? (R = 0.0821 L • atm/(K • mol))
2C6H6(l) + 15O2(g) → 12CO2(g) + 6H2O(l)
A)
–2.35 101 kJ
B)
–3.22 102 kJ
C)
–5.36 103 kJ
D)
–3.27 103 kJ
E)
–6.53 103 kJ
48. When 49.4 mL of 0.721 M lead(II) nitrate reacts with 99.6 mL of 0.807 M sodium chloride,
0.830 kJ of heat is released at constant pressure. What is H° for this reaction?
Pb(NO3)2(aq) + 2NaCl(aq) → PbCl2(s) + 2NaNO3(aq)
A)
–23.3 kJ
B)
–10.3 kJ
C)
–4.23 kJ
D)
–7.15 kJ
E)
–20.6 kJ
Test Bank General Chemistry, 10th edition 16
49. A 9.020-g sample of an unknown metal M is burned in the presence of excess oxygen,
producing the oxide M2O3(s) and liberating 191.5 kJ of heat at constant pressure. What is
the identity of the metal?
4M(s) + 3O2(g) → 2M2O3(s)
Substance
Yb2O3(s)
Tb2O3(s)
Sm2O3(s)
Sc2O3(s)
Y2O3(s)
A)
Sm
B)
Sc
C)
Yb
D)
Y
E)
Tb
50. A 5.09-g sample of solid silver reacted in excess chlorine gas to give a 6.76-g sample of
pure solid AgCl. The heat given off in this reaction was 6.00 kJ at constant pressure. Given
this information, what is the enthalpy of formation of AgCl(s)?
A)
–127 kJ/mol
B)
–63.6 kJ/mol
C)
127 kJ/mol
D)
–6.00 kJ/mol
E)
6.00 kJ/mol
51. A 2.19-g sample of solid calcium reacted in excess fluorine gas to give a 4.27-g sample of
pure solid CaF2. The heat given off in this reaction was 67.0 kJ at constant pressure. Given
this information, what is the enthalpy of formation of CaF2(s)?
A)
67.0 kJ/mol
B)
–67.0 kJ/mol
C)
–1.23 103 kJ/mol
D)
–613 kJ/mol
E)
1.23 103 kJ/mol
52. The quantity of heat required to raise the temperature of a sample of a substance by 1°C is
the sample’s
A)
work.
B)
calorimetry.
C)
heat capacity.
D)
specific heat.
E)
enthalpy.
53. The units for heat capacity are
A)
J/g.
B)
(J · g).
C)
J/°C.
D)
(J · °C).
E)
J/(g · °C).
54. The units for specific heat are
A)
J/(g · °C).
B)
(J · °C).
C)
J/g.
D)
J/°C.
E)
(J · g).
Test Bank General Chemistry, 10th edition 18
55. The specific heat capacity of copper is 0.384 J/gC. What is the molar specific heat
capacity of this substance? The molar mass of copper is 63.54 g/mol.
A)
24.4 J/molC
B)
0.00604 J/molC
C)
165 J/molC
D)
0.384 J/molC
E)
2.60 J/molC
56. The heat required to raise the temperature of 52.00 g of chromium by 1°C is called its
A)
heat of vaporization.
B)
specific heat.
C)
heat of fusion.
D)
entropy.
E)
molar heat capacity.
57. The molar heat capacity of gaseous heptane at 25.0°C is 165.2 J/(mol · °C). What is its
specific heat?
A)
0.6065 J/(g · °C)
B)
1.649 J/(g · °C)
C)
6.041 10–5 J/(g · °C)
D)
165.2 J/(g · °C)
E)
1.655 104 J/(g · °C)
58. A 100 g sample of each of the following metals is heated from 35C to 45C. Which metal
absorbs the lowest amount of heat energy?
Metal
Specific Heat
copper
0.385 J/(g · °C)
magnesium
1.02 J/(g · °C)
mercury
0.138 J/(g · °C)
silver
0.237 J/(g · °C)
lead
0.129 J/(g · °C)
Test Bank General Chemistry, 10th edition 19
A)
lead
B)
magnesium
C)
silver
D)
mercury
E)
copper
59. Two metals of equal mass with different heat capacities are subjected to the same amount of
heat. Which undergoes the smaller change in temperature?
A)
The metal with the higher heat capacity undergoes the smaller change in
temperature.
B)
Both undergo the same change in temperature.
C)
You need to know the initial temperatures of the metals.
D)
You need to know which metals you have.
E)
The metal with the lower heat capacity undergoes the smaller change in
temperature.
60. It is relatively easy to change the temperature of a substance that
A)
is very massive.
B)
is an insulator.
C)
has a high specific heat capacity.
D)
has a low specific heat capacity.
E)
is brittle.
61. How much heat is gained by copper when 51.8 g of copper is warmed from 15.5°C to
76.4°C? The specific heat of copper is 0.385 J/(g · °C).
A)
3.09 102 J
B)
29.41 J
C)
23.45 J
D)
1.21 103 J
E)
1.52 103 J
62. Which of the following processes will result in the lowest final temperature of the metal–
water mixture at equilibrium?
A)
the addition of 100 g of silver (s = 0.237 J/(g · °C)) at 95°C to 100 mL of water at
25°C in an insulated container
B)
the addition of 100 g of cobalt (s = 0.418 J/(g · °C)) at 95°C to 100 mL of water at
25°C in an insulated container
C)
the addition of 100 g of chromium (s = 0.447 J/(g · °C)) at 95°C to 100 mL of
water at 25°C in an insulated container
D)
the addition of 100 g of copper (s = 0.385 J/(g · °C)) at 95°C to 100 mL of water at
25°C in an insulated container
E)
the addition of 100 g of gold (s = 0.129 J/(g · °C)) at 95°C to 100 mL of water at
25°C in an insulated container
63. Which of the following processes will result in the lowest final temperature of the metal–
water mixture at equilibrium? The specific heat of cobalt is 0.421 J/(g · °C).
A)
the addition of 100 g of cobalt at 95°C to 80 mL of water at 25°C in an insulated
container
B)
the addition of 100 g of cobalt at 95°C to 100 mL of water at 25°C in an insulated
container
C)
the addition of 100 g of cobalt at 95°C to 40 mL of water at 25°C in an insulated
container
D)
the addition of 100 g of cobalt at 95°C to 20 mL of water at 25°C in an insulated
container
E)
the addition of 100 g of cobalt at 95°C to 60 mL of water at 25°C in an insulated
container