71) If 356 J of work is done by a system while it loses 289 J of heat, what is the value of
A) +645 J
B) -645 J
C) +67 J
D) -67 J
E) +134 J
72) The complete combustion of propane, C3H8(g), is represented by the equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔrH° = -2220 kJ/mol
How much heat is evolved in the complete combustion of 2.50 g C3H8(g)?
A) 245 kJ
B) 50.4 kJ
C) 126 kJ
D) 5.56 kJ
E) 2.22 kJ
73) Complete combustion of 75.0 g acetylene, C2H2, liberated 3750 kJ of heat. What is the heat of
combustion, ΔrHcomb, of acetylene?
A) -50.0 kJ/mol
B) +50.0 kJ/mol
C) +1302 kJ/mol
D) -1302 kJ/mol
E) -0.521 kJ/mol
74) The heat of combustion of methane is -50.38 kJ/mol. How many moles of methane must be burned to
produce 137 kJ of heat?
A) 6.90 mol
B) 0.367 mol
C) 2.72 mol
D) 1.37 mol
E) 0.272 mol
19
75) A certain reaction releases 10.1 kJ at constant volume and at constant pressure releases 8.4 kJ. What is
△U for the reaction?
A) -10.1 kJ
B) -8.4 kJ
C) +8.4 kJ
D) -1.7 kJ
76) The complete combustion of propane, C3H8(g), is represented by the equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔrH° = -2220 kJ /mol
How much heat is evolved in the complete combustion of 20.0 L C3H8(g) at STP?
A) 2486 kJ
B) 1007 kJ
C) 994 kJ
D) 1957 kJ
E) 495 kJ
77) For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔrH° = -241.8 kJ/mol,
what mass of H2(g) is required to liberate 1.00 × 103 kJ of heat?
A) 66.2 g
B) 4.17 g
C) 8.34 g
D) 2.05 g
E) 16.7 g
20
78) The complete combustion of propane, C3H8(g), is represented by the equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔrH° = -2220 kJ /mol
How much heat is evolved in the complete combustion of 12.5 L C3H8(g) at 25 °C and 790 mmHg?
A) 8.27 × 104 kJ
B) 1.41 × 104 kJ
C) 653 kJ
D) 168 kJ
E) 1180 kJ
79) For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔrH° = -241.8 kJ/mol,
what quantity of heat is liberated by the reaction of 10.0 L of O2 measured at 22.0 °C and 742 mmHg?
A) 120 kJ
B) 2610 kJ
C) 1310 kJ
D) 195 kJ
E) 97.5 kJ
80) For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔrH° = -241.8 kJ/mol,
what quantity of heat, in kJ, evolved when a 72.0 g mixture containing equal parts of H2 and O2, by mass,
is burned?
A) 8630 kJ
B) 4860 kJ
C) 1088 kJ
D) 272 kJ
E) 544 kJ
81) How much heat is involved in the complete combustion of 2.50 kg propane, C3H8?
ΔrHcomb = -2219 kJ/mol
A) 1.26 × 105 kJ
B) 5.55 × 103 kJ
C) 126 kJ
D) 503 kJ
E) 49.7 kJ
82) Determine △rH° for the decomposition of hydrogen peroxide.
H2O2(l) → O2(g) + H2O(l)
Given: H2(g) + O2(g) → H2O2(l) △rH° = -187.78 kJ/mol
H2(g) + O2(g) → H2O(l) △rH° = -285.83 kJ/mol
A) -98.05 kJ/mol
B) +93.89 kJ/mol
C) -191.94 kJ/mol
D) -93.89 kJ/mol
83) Given the reactions below, compute ΔrH° for the reaction:
(ΔH‘s are all given in kJ/mol)
2 MnO2(s) + CO(g) → Mn2O3(s) + CO2(g)
Reaction ΔrH°
MnO2(s) + CO(g) → MnO(s) + CO2(g) -150.6
Mn3O4(s) + CO(g) → 3 MnO(s) + CO2(g) -54.4
3 Mn2O3(s) + CO(g) → 2 Mn3O4(s) + CO2(g) -142.3
A) -347.3 kJ/mol
B) -46.1 kJ/mol
C) -217.1 kJ/mol
D) -104.5 kJ/mol
E) -389.1 kJ/mol
22
84) Combine the reactions:
P4(s) + 6 Cl2(g) → 4 PCl3(g) ΔrH°298 = -1225.0 kJ/mol
PCl3(g) + 3 H2O(l) → H3PO3(aq) + 3 HCl(g) = -853.5 kJ/mol
2 H2(g) + O2(g) → 2 H2O(l) = -571.5 kJ/mol
H2(g) + Cl2(g) → 2 HCl(g) = -184.9 kJ/mol
to obtain the reaction: P4(s) + 6 H2(g) + 6 O2(g) → 4 H3PO3(aq).
What is the value of ΔrH°298 for this reaction?
A) -2465.1 kJ/mol
B) -6958.6 kJ/mol
C) -2834.9 kJ/mol
D) -9177.4 kJ/mol
E) 8605.9 kJ/mol
85) Some “beetles” defend themselves by spraying hot quinone, C6H4O2(l), at their enemies. Calculate
△rH° for this reaction.
C6H4(OH)2(l) + H2O2(l) → C6H4O2(l) + 2 H2O(l)
Given: C6H4(OH)2(l) → C6H4O2(l) + H2(g) +177.4 kJ/mol
The standard enthalpies of formation of H2O2(l) and H2O(l) are -187.4 and -285.8 kJ/mol, respectively.
A) -206.8 kJ/mol
B) -384.2 kJ/mol
C) -561.6 kJ/mol
D) +79.00 kJ/mol
23
86) H2S(g) + O2(g) → H2O (l) + SO2(g) ΔrH° = -562.3 kJ/mol
1/8 S8(s) + O2(g) → SO2(g) ΔrH° = -297.0 kJ/mol
H2(g) + O2 → H2O (l) ΔrH° = -266.9 kJ/mol
Compute ΔrH° for H2(g) + 1/8 S8 (s) → H2S(g) in kJ/mol.
A) 562.3 kJ/mol
B) 276.6 kJ/mol
C) 265.3 kJ/mol
D) 20.5 kJ/mol
E) -1.6 kJ/mol
87) Given the following thermochemical equations:
(kJ/mol)
4 FeS2(s) + 11 O2(g) → 2 Fe2O3(s) + 8 SO2(g) ΔrH° = -3307.9
2 H2S(g) + 3 O2(g) → 2 H2O(l) + 2 SO2(g) – 1125.2
4 FeO(s) + O2(g) → 2 Fe2O3(s) – 578.2
2 Fe(s) + O2(g) → 2 FeO(s) – 544
H2(g) + S(s) → H2S(g) – 20.2
2 H2(g) + O2(g) → 2 H2O(l) – 571.7
Compute the ΔfH° for FeS2(s) in kJ/mol.
A) -1233.9 kJ/mol
B) -2893.9 kJ/mol
C) -24.3 kJ/mol
D) -183.5 kJ/mol
E) -70.0 kJ/mol
24
88) Using the heat of combustion of methanol as -726.6 kJ/mol and the following data:
C(graphite) + 1/2 O2 →CO(g) ΔH° = -110.5 kJ/mol
C(graphite) + O2(g) → CO2(g) ΔH° = -393.5 kJ/mol
H2(g) + 1/2 O2(g) → H2O(l) ΔH° = -285.8 kJ/mol
Determine ΔrH° for the following reaction:
CO(g) + 2 H2(g) → CH3OH(l)
A) -349 kJ/mol
B) 157.8 kJ/mol
C) -157.8 kJ/mol
D) 128 kJ/mol
E) -128 kJ/mol
89) Compute ΔrH° for the following reaction. The value of ΔfH° in kJ/mol is given below each species:
2 CaO(s) + 2 SO2(g) + O2(g) → 2 CaSO4(s)
-635.5 -296.9 0.0 -1432.7
A) -1000.6 kJ/mol
B) -500.3 kJ /mol
C) 500.3 kJ /mol
D) -2365.1 kJ /mol
E) -1094.1 kJ/mol
90) Consider the reaction: CO2(g) + 2 HCl(g) → COCl2(g) + H2O(l)
ΔfH° -393.51 -92.30 -223.01 -285.85 kJ/mol
Compute ΔrH° for this reaction.
A) -994.67 kJ/mol
B) 23.05 kJ /mol
C) -23.05 kJ /mol
D) 69.25 kJ /mol
E) -69.25 kJ/mol
91) Given the heat of formation of the following compounds:
CO2(g) ΔfH° = -393.5 kJ/mol
H2O(l) ΔfH° = -285.9 kJ/mol
CH3OH(l) ΔfH° = -238.6 kJ/mol
What is the value of ΔrH° for the reaction:
CH3OH(l) + 3/2 O2(g) → CO2(g) + 2 H2O(l)
A) -440.8 kJ/mol
B) -416.9 kJ/mol
C) -1203.9 kJ/mol
D) -346.2 kJ/mol
E) -726.7 kJ/mol
92) Given that ΔfH°[CO(g)] = –110.5 kJ/mol and ΔfH° [COCl2(g)] = -219.1 kJ/mol, what is the enthalpy of
reaction for the formation of phosgene, COCl2 from carbon monoxide, CO, and chlorine gas, Cl2(g)?
A) +110.5 kJ /mol
B) -110.5 kJ/mol
C) +329.6 kJ /mol
D) -108.6 kJ/mol
E) -219.1 kJ/mol
93) Determine the enthalpy change in the following equation:
2 NH3(g) → N2(g) + 3 H2(g)
ΔfH° NH3(g) = -46.11 kJ/mol
A) 92.22 kJ/mol
B) 46.11 kJ/mol
C) 5.42 kJ/mol
D) -92.22 kJ/mol
E) -46.11 kJ/mol
94) Compute ΔrH° for the following reaction. The value of ΔfH° in kJ/mol is given below each species:
PCl5(g) + 4 H2O(l) → H3PO4(s) + 5 HCl(g)
-398.9 -285.9 -1281.1 -92.30
A) -688.6 kJ/mol
B) -200.1 kJ/mol
C) -74.9 kJ/mol
D) -1000.6 kJ/mol
E) -900.3 kJ/mol
95) The heat of combustion, ΔrHcomb, of 1-butene(l), C4H8(l), is -2696.9 kJ/mol. From the following
values of ΔfH° CO2(g) = –393.5 kJ/mol and ΔfH° H2O(l) = -285.8 kJ/mol, calculate the standard enthalpy of
formation of butene(l).
A) +2017 kJ/mol
B) -2017 kJ/mol
C) -3376 kJ/mol
D) -107.7 kJ/mol
E) -20.30 kJ/mol
96) Given that ΔfH° [Ag2S(s)] = -32.6 kJ/mole, what is the enthalpy change for the precipitation of
argentite, Ag2S(s)?
ΔfH° [Ag+(aq)] = +105.6 kJ/mol
ΔfH° [S2-(aq)] = +33.05 kJ/mol
A) -276.9 kJ/mol
B) -106.1 kJ/mol
C) +171.2 kJ/mol
D) +106.1 kJ/mol
E) +138.7 kJ/mol
97) What is the enthalpy of reaction for the neutralization reaction occurring between dilute Ba(OH)2(aq)
and dilute HNO3(aq)? Values of ΔfH° from data tables are given below.
Hint: Balance the equation so the coefficients are the lowest possible set of whole numbers.
Species ΔfH°(kJ/mol)
Ba2+(aq) -537.6
OH–(aq) -230.0
H+(aq) 0
NO3–(aq) -205.0
H2O(l) -285.8
A) +426.0 kJ/mol
B) -111.6 kJ/mol
C) -426.0 kJ/mol
D) -571.6 kJ/mol
E) -460.0 kJ/mol
98) Determine the enthalpy change in the following equation:
2/3 H2S(g) + O2(g) → 2/3 SO2(g) + 2/3 H2O(l)
ΔfH° H2O(l) = -285.8 kJ/mol
Δf H° H2S(g) = -20.63 kJ/mol
Δf H° SO2(g) = -296.8 kJ/mol
A) -562 kJ/mol
B) -375 kJ/mol
C) 375 kJ /mol
D) -402 kJ/mol
E) 402 kJ/mol
99) Determine the enthalpy change in the following equation:
Cl2(g) + H2O(l) → 2 HCl(g) + 1/2 O2(g)
ΔfH° H2O(l) = -285.8 kJ/mol
ΔfH° HCl(g) = -92.31 kJ/mol
A) 193.5 kJ/mol
B) -470.4 kJ/mol
C) 470.4 kJ/mol
D) 101.2 kJ/mol
E) -101.2 kJ/mol
100) The standard heat of formation of solid ammonium bromide is -270.8 kJ/mol. Write the chemical
equation for the reaction to which this value applies.
101) For a process at constant pressure, 49,600 calories of heat are released. This quantity of heat is
equivalent to:
A) 4.82 × 10–6 J
B) 1.19 × 104 J
C) 1.24 × 104 J
D) 2.08 × 105 J
102) Calculate the kinetic energy of a 150 g baseball moving at a speed of 39. m (87 mph).
A) 5.8 J
B) 1.1 × 102 J
C) 5.8 × 103 J
D) 1.1 × 105 J
103) Calculate the work, w, gained or lost by the system when a gas expands from 15 L to 40 L against a
constant external pressure of 1.5199 bar.
A) -6.1 kJ
B) -3.8 kJ
C) +3.8 kJ
D) +6.1 kJ
104) The specific heat capacity of liquid mercury is 0.14 J . How many joules of heat are needed to
raise the temperature of 5.00 g of mercury from 15.0 °C to 36.5 °C?
A) 7.7 × 102 J
B) 15 J
C) 36 J
D) 0.0013 J
E) 1.7 J
105) The specific heat capacity of solid copper metal is 0.385 J . How many joules of heat are
needed to raise the temperature of a 1.55 kg block of copper from 33.0 °C to 77.5 °C?
A) 1.79 × J
B) 26.6 J
C) 2.66 × J
D) 5.58 × J
E) 0.00558 J
106) A 5.00 g sample of liquid water at 25.0 °C is heated by the addition of 145 J of energy. The final
temperature of the water is ________ °C. The specific heat capacity of liquid water is
A) 146
B) 25.1
C) -18.1
D) 31.9
E) 6.94
107) A 5.00 g sample of copper metal at 25.0 °C is heated by the addition of 96.0 J of energy. The final
temperature of the copper is ________ °C. The specific heat capacity of copper is
A) 32.3
B) 25.0
C) 25.5
D) 75.5
E) 50.5
108) The specific heat capacity of liquid water is 4.184 J . How many joules of heat are needed to
raise the temperature of 6.00 g of water from 36.0 °C to 75.0 °C?
A) 56.0 J
B) 978 J
C) 2.78 × J
D) 1.79 × J
E) 52.3 J
109) The specific heat capacity of methane gas is 2.20 J . How many joules of heat are needed to
raise the temperature of 5.00 g of methane from 36.0 °C to 75.0 °C?
A) 88.6 J
B) 429 J
C) 1221 J
D) 0.0113 J
E) 22.9 J
110) The specific heat of copper is 0.385 J . If 34.2 g of copper, initially at 21.0 °C, absorbs 4.689 kJ,
what will be the final temperature of the copper?
A) 21.4 °C
B) 23.8 °C
C) 356 °C
D) 377 °C
111) A 50.0 g sample of liquid water at 25.0 °C is mixed with 23.0 g of water at 89.0 °C. The final
temperature of the water is ________ °C.
A) 132
B) 27.3
C) 57.0
D) 260
E) 45.2
112) What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 mL of
solution having a density of 1.25 g by 10.2 °C? (The specific heat of the solution is 3.733 J .)
A) -7.43 kJ
B) -12.51 kJ
C) 8.20 kJ
D) -11.9 kJ
E) 6.51 kJ
113) The combustion of titanium with oxygen produces titanium dioxide:
Ti(s) + (g) → (s)
When 2.060 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter
increases from 25.00 °C to 91.60 °C. In a separate experiment, the heat capacity of the calorimeter is
measured to be 9.84 kJ . The heat of reaction for the combustion of a mole of Ti in this calorimeter is
________ kJ .
A) 14.3
B) 19.6
C) -311
D) -0.154
E) -1.52 ×
114) For a particular process that is carried out at constant pressure, q = 145 kJ and w = -35 kJ. Therefore:
A) ΔU = 110 kJ and ΔH = 145 kJ
B) ΔU = 145 kJ and ΔH = 110 kJ
C) ΔU = 145 kJ and ΔH = 180 kJ
D) ΔU = 180 kJ and ΔH = 145 kJ
115) 8.000 moles of H2(g) reacts with 4.000 mol of O2(g) to form 8.000 mol of H2O(l) at 25 °C and a
constant pressure of 1.0133 bar. If 546.4 kJ of heat are released during this reaction, and PΔV is equal to –
29.60 kJ, then:
A) ΔH° = +546.4 kJ and ΔU = +576.06 kJ
B) ΔH° = +546.4 kJ and ΔU = +516.8 kJ
C) ΔH° = –546.4 kJ and ΔU = -516.8 kJ
D) ΔH° = –546.4 kJ and ΔU = -576.0 kJ
116) At 1.0133 bar, the heat of sublimation of gallium is 277 kJ and the heat of vaporization is 271 kJ
. To the correct number of significant figures, how much heat is required to melt 5.50 mol of
gallium at 1.0133 bar?
A) 6 kJ
B) 33 kJ
C) 244 kJ
D) 274 kJ
117) How much heat is absorbed/released when 40.00 g of NH3(g) reacts in the presence of excess (g)
to produce NO(g) and H2O(l) according to the following chemical equation?
4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l) H° = 1168 kJ
A) 685.8 kJ of heat are absorbed.
B) 685.8 kJ of heat are released.
C) 2743 kJ of heat are absorbed.
D) 2743 kJ of heat are released.
118) How much heat is absorbed when 45.00 g of C(s) reacts in the presence of excess SO2(g) to produce
CS2(l) and CO(g) according to the following chemical equation?
5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g) H° = 239.9 kJ
A) 179.8 kJ
B) 239.9 kJ
C) 898.5 kJ
D) 2158 kJ
119) At constant pressure, the combustion of 20.0 g of C2H6(g) releases 1036 kJ of heat. What is ΔH for the
reaction given below?
2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l)
A) -173 kJ
B) -779 kJ
C) -1560 kJ
D) -3115 kJ
120) When 1.50 mol of CH4(g) reacts with excess Cl2(g) at constant pressure according to the chemical
equation shown below, 1062 kJ of heat are released. Calculate the value of ΔH for this reaction, as written.
2 CH4(g) + 3 Cl2(g) → 2 CHCl3(l) + 3 H2(g) H° = ?
A) -1420 kJ
B) -708 kJ
C) +708 kJ
D) +1420 kJ
121) In the presence of excess oxygen, methane gas burns in a constant-pressure system to yield carbon
dioxide and water:
(g) + (g) → (g) + O (l) H = -890.0 kJ
Calculate the value of q (kJ) in this exothermic reaction when 1.90 g of methane is combusted at constant
pressure.
A) -105.7 kJ
B) 0.0342 kJ
C) -0.0095 kJ
D) 29.3 kJ
E) -1.06 × 105 kJ
122) Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction:
(l) → O(l) + (g) H = -196 kJ
Calculate the value of q (kJ) in this exothermic reaction when 4.00 g of hydrogen peroxide decomposes at
constant pressure?
A) -23.1 kJ
B) -11.5 kJ
C) -0.0217 kJ
D) 1.44 kJ
E) -2.31 × 104 kJ
123) When 2.50 g of Ba(s) is added to 100.00 g of water in a container open to the atmosphere, the reaction
shown below occurs and the temperature of the resulting solution rises from 22.00 °C to 40.32 °C. If the
specific heat of the solution is 4.18 J , calculate for the reaction, as written.
Ba(s) + 2 H2O(l) → Ba(OH)2(aq) + H2(g) = ?
A) -431 kJ
B) -3.14 kJ
C) +3.14 kJ
D) +431 kJ
124) Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the
chemical equation shown below. When 0.015 mol of Na is added to 100.00 g of water, the temperature of
the resulting solution rises from 25.00 °C to 31.45 °C. If the specific heat of the solution is 4.18 J ,
calculate ΔH for the reaction, as written.
2 Na(s) + 2 H2O(l) → 2 NaOH(aq) + H2(g) H = ?
A) -5.41 kJ
B) -90.0 kJ
C) -180 kJ
D) -360 kJ
125) When 50.0 mL of 0.400 mol L-1 Ca(NO3)2 is added to 50.0 mL of 0.800 mol L-1 NaF, CaF2
precipitates, as shown in the net ionic equation below. The initial temperature of both solutions is 23.0 °C.
Assuming that the reaction goes to completion, and that the resulting solution has a mass of 100.00 g and
a specific heat of 4.18 J , calculate the final temperature of the solution.
Ca2+(aq) + 2 F–(aq) → CaF2(s) H = -11.5 kJ
A) 22.45 °C
B) 23.55 °C
C) 24.10 °C
D) 24.65 °C