Question 1

Which of the following are thermodynamic state functions? 
I. heat
II. volume
III. temperature
IV. enthalpy
V. density

Accepted Answer

A)  II, III, IV, V 
B)  I, II, IV, V 
C)  I, II, III, V 
D)  II, IV 
E)  I, III, V 
A)  II, III, IV, V 
B)  I, II, IV, V 
C)  I, II, III, V 
D)  II, IV 
E)  I, III, V

Question 2

For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔH° = -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?

Accepted Answer

A)  8630 kJ 
B)  4860 kJ 
C)  1088 kJ 
D)  272 kJ 
E)  544 kJ 
A)  8630 kJ 
B)  4860 kJ 
C)  1088 kJ 
D)  272 kJ 
E)  544 kJ

Question 3

Two solutions, 250.0 mL of 1.00 M CaCl2(aq) and 250.0 mL of 1.00 M K2SO4(aq), are added to a calorimeter with a total heat capacity, after the solutions are added, of 1.25 kJ/°C and the temperature decreased by 2.40°C. Determine qrxn per mole of CaSO4(s) formed in the reaction.

Accepted Answer

A)  +12.0 kJ/mol 
B)  -12.0 kJ/mol 
C)  +6.00 kJ/mol 
D)  -6.00 kJ/mol 
A)  +12.0 kJ/mol 
B)  -12.0 kJ/mol 
C)  +6.00 kJ/mol 
D)  -6.00 kJ/mol

Question 4

A closed system can exchange matter but not energy with the surroundings.

Accepted Answer

A) True 
 B)False

Question 5

The complete combustion of propane, C3H8(g), is represented by the equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ
How much heat is evolved in the complete combustion of 2.50 g C3H8(g)?

Accepted Answer

A)  245 kJ 
B)  50.4 kJ 
C)  126 kJ 
D)  5.56 kJ 
E)  2.22 kJ 
A)  245 kJ 
B)  50.4 kJ 
C)  126 kJ 
D)  5.56 kJ 
E)  2.22 kJ

Question 6

The complete combustion of 1 mole of nitrobenzene, C6H5NO2, in a bomb calorimeter liberates 3088 kJ of heat and increases the temperature of the calorimeter assembly by 140.0 °C. What is the heat capacity of this bomb calorimeter?

Accepted Answer

A)  1.25 kJ/°C 
B)  4.53 kJ/°C 
C)  22.1 kJ/°C 
D)  432 kJ/°C 
E)  43.1 kJ/°C 
A)  1.25 kJ/°C 
B)  4.53 kJ/°C 
C)  22.1 kJ/°C 
D)  432 kJ/°C 
E)  43.1 kJ/°C

Question 7

Complete combustion of 75.0 g acetylene, C2H2, liberated 3750 kJ of heat. What is the heat of combustion, ΔHcomb, of acetylene?

Accepted Answer

A)  -50.0 kJ/mol 
B)  +50.0 kJ/mol 
C)  +1302 kJ/mol 
D)  -1302 kJ/mol 
E)  -0.521 kJ/mol 
A)  -50.0 kJ/mol 
B)  +50.0 kJ/mol 
C)  +1302 kJ/mol 
D)  -1302 kJ/mol 
E)  -0.521 kJ/mol

Question 8

Calculate the quantity of heat, in kJ, required to raise the temperature of a 2.15 kg iron bar 24.0°C (specific heat of iron = 0.473 J/g °C).

Accepted Answer

A)  109 kJ 
B)  51.6 kJ 
C)  23.6 kJ 
D)  24.4 kJ 
E)  11.3 kJ 
A)  109 kJ 
B)  51.6 kJ 
C)  23.6 kJ 
D)  24.4 kJ 
E)  11.3 kJ

Question 9

Calculate ΔU for a system that loses 475 kJ of heat and does 155 kJ of expansion work on the surroundings.

Accepted Answer

A)  -630 kJ 
B)  -320 kJ 
C)  +630 kJ 
D)  +320 kJ 
A)  -630 kJ 
B)  -320 kJ 
C)  +630 kJ 
D)  +320 kJ

Question 10

246 g of hot coffee at 86.0°C are placed in a 137 g mug at 20.0°C. The specific heat of coffee is 4.00 J/g °C, while that of the mug is 0.752 J/g °C. Assuming no heat is lost to the surroundings, what is the final temperature of the system: mug + coffee?

Accepted Answer

A)  79.7 °C 
B)  93.7 °C 
C)  98.4 °C 
D)  76.0 °C 
E)  53.0 °C 
A)  79.7 °C 
B)  93.7 °C 
C)  98.4 °C 
D)  76.0 °C 
E)  53.0 °C

Question 11

If 356 J of work is done by a system while it loses 289 J of heat, what is the value of ΔU ?

Accepted Answer

A)  +645 J 
B)  -645 J 
C)  +67 J 
D)  -67 J 
E)  +134 J 
A)  +645 J 
B)  -645 J 
C)  +67 J 
D)  -67 J 
E)  +134 J

Question 12

Determine the enthalpy change in the following equation: 2 NH3(g) → N2(g) + 3 H2(g)&emsp;ΔH°f NH3(g) = -46.11 kJ/mol

Accepted Answer

A)  92.22 kJ 
B)  46.11 kJ 
C)  5.42 kJ 
D)  -92.22 kJ 
E)  -46.11 kJ 
A)  92.22 kJ 
B)  46.11 kJ 
C)  5.42 kJ 
D)  -92.22 kJ 
E)  -46.11 kJ

Question 13

The combustion of 90.0 g of oxalic acid, C2H2O4(s) in a bomb calorimeter whose heat capacity is 4.60 kJ/°C causes the temperature to rise from 25.0°C to 79.6°C. What is the heat of combustion of oxalic acid?

Accepted Answer

A)  -21.2 kJ/mol 
B)  -54.6 kJ/mol 
C)  -126 kJ/mol 
D)  -211 kJ/mol 
E)  -251 kJ/mol 
A)  -21.2 kJ/mol 
B)  -54.6 kJ/mol 
C)  -126 kJ/mol 
D)  -211 kJ/mol 
E)  -251 kJ/mol

Question 14

250.0 g of hot coffee at 95.0°C are placed in a 0.2000 kg mug at 20.0°C. The specific heat of the coffee is 4.00 J/g °C, while that of the mug is 0.80 J/g °C. Assuming no heat is lost to the surroundings, what is the final temperature of the system: mug + coffee?

Accepted Answer

A)  61.7 °C 
B)  117 °C 
C)  76.0 °C 
D)  57.5 °C 
E)  84.7 °C 
A)  61.7 °C 
B)  117 °C 
C)  76.0 °C 
D)  57.5 °C 
E)  84.7 °C

Question 15

Some "beetles" defend themselves by spraying hot quinone, C6H4O2(l), at their enemies. Calculate △H° for this reaction. C6H4(OH)2(l) + H2O2(l) → C6H4O2(l) + 2H2O(l)
Given: C6H4(OH)2(l) → C6H4O2(l) + H2(g) +177.4 kJ
The standard enthalpies of formation of H2O2(l) and H2O(l) are -187.4 and -285.8 kJ/mol, respectively.

Accepted Answer

A)  -206.8 kJ 
B)  -384.2 kJ 
C)  -561.6 kJ 
D)  +79.00 kJ 
A)  -206.8 kJ 
B)  -384.2 kJ 
C)  -561.6 kJ 
D)  +79.00 kJ

Question 16

14.0 g of metal at 24.0°C has 250 joules of heat added to it. The metal's specific heat is 0.105 J/g °C. What is its final temperature?

Accepted Answer

A)  (250)(14.0)/0.105 °C 
B)  [250/(14.0)(0.105)] °C 
C)  [(914.0)(0.105)/250] + 24.0 °C 
D)  (14.0)(0.105)/250 °C 
E)  (14.0)(0.105)(250) °C 
A)  (250)(14.0)/0.105 °C 
B)  [250/(14.0)(0.105)] °C 
C)  [(914.0)(0.105)/250] + 24.0 °C 
D)  (14.0)(0.105)/250 °C 
E)  (14.0)(0.105)(250) °C

Question 17

Given that ΔH°f [Ag2S(s)] = -32.6 kJ/mole, what is the enthalpy change for the precipitation of argentite, Ag2S(s)? ΔH°f [Ag+(aq)] = +105.6 kJ/mol
ΔH°f [S2-(aq)] = +33.05 kJ/mol

Accepted Answer

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 
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

Question 18

Coal contains an impurity that reacts with oxygen during the combustion process, producing oxides that are major environmental pollutants. This impurity is:

Accepted Answer

A)  acid rain 
B)  nitrogen 
C)  sulfur 
D)  carbon dioxide 
E)  peat 
A)  acid rain 
B)  nitrogen 
C)  sulfur 
D)  carbon dioxide 
E)  peat

Question 19

Calculate the enthalpy change for the following reaction at 25°C. The value of ΔH°f in kJ/mol is given below each species:

Accepted Answer

A)  -49.6 kJ 
B)  541 kJ 
C)  -1380 kJ 
D)  -3350 kJ 
E)  -24.8 kJ 
A)  -49.6 kJ 
B)  541 kJ 
C)  -1380 kJ 
D)  -3350 kJ 
E)  -24.8 kJ

Question 20

Heat is usually transferred from a cold object to a hot object.

Accepted Answer

A) True 
 B)False

Exam 7: Thermochemistry

Which of the following are thermodynamic state functions? I. heat II. volume III. temperature IV. enthalpy V. density

For the reaction H2(g) + 1/2 O2(g) → H2O(g) ΔH° = -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?

Two solutions, 250.0 mL of 1.00 M CaCl2(aq) and 250.0 mL of 1.00 M K2SO4(aq), are added to a calorimeter with a total heat capacity, after the solutions are added, of 1.25 kJ/°C and the temperature decreased by 2.40°C. Determine qrxn per mole of CaSO4(s) formed in the reaction.

A closed system can exchange matter but not energy with the surroundings.

The complete combustion of propane, C3H8(g), is represented by the equation: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l) ΔH° = -2220 kJ How much heat is evolved in the complete combustion of 2.50 g C3H8(g)?

The complete combustion of 1 mole of nitrobenzene, C6H5NO2, in a bomb calorimeter liberates 3088 kJ of heat and increases the temperature of the calorimeter assembly by 140.0 °C. What is the heat capacity of this bomb calorimeter?

Complete combustion of 75.0 g acetylene, C2H2, liberated 3750 kJ of heat. What is the heat of combustion, ΔHcomb, of acetylene?

Calculate the quantity of heat, in kJ, required to raise the temperature of a 2.15 kg iron bar 24.0°C (specific heat of iron = 0.473 J/g °C).

Calculate ΔU for a system that loses 475 kJ of heat and does 155 kJ of expansion work on the surroundings.

246 g of hot coffee at 86.0°C are placed in a 137 g mug at 20.0°C. The specific heat of coffee is 4.00 J/g °C, while that of the mug is 0.752 J/g °C. Assuming no heat is lost to the surroundings, what is the final temperature of the system: mug + coffee?

If 356 J of work is done by a system while it loses 289 J of heat, what is the value of ΔU ?

Determine the enthalpy change in the following equation: 2 NH3(g) → N2(g) + 3 H2(g) ΔH°f NH3(g) = -46.11 kJ/mol

The combustion of 90.0 g of oxalic acid, C2H2O4(s) in a bomb calorimeter whose heat capacity is 4.60 kJ/°C causes the temperature to rise from 25.0°C to 79.6°C. What is the heat of combustion of oxalic acid?

250.0 g of hot coffee at 95.0°C are placed in a 0.2000 kg mug at 20.0°C. The specific heat of the coffee is 4.00 J/g °C, while that of the mug is 0.80 J/g °C. Assuming no heat is lost to the surroundings, what is the final temperature of the system: mug + coffee?

14.0 g of metal at 24.0°C has 250 joules of heat added to it. The metal's specific heat is 0.105 J/g °C. What is its final temperature?

Given that ΔH°f [Ag2S(s)] = -32.6 kJ/mole, what is the enthalpy change for the precipitation of argentite, Ag2S(s)? ΔH°f [Ag+(aq)] = +105.6 kJ/mol ΔH°f [S2-(aq)] = +33.05 kJ/mol

Coal contains an impurity that reacts with oxygen during the combustion process, producing oxides that are major environmental pollutants. This impurity is:

Calculate the enthalpy change for the following reaction at 25°C. The value of ΔH°f in kJ/mol is given below each species:

Heat is usually transferred from a cold object to a hot object.

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding I: Basic Concepts

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

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Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

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For the reaction H₂(g) + 1/2 O₂(g) → H₂O(g) ΔH° = -241.8 kJ/mol, what quantity of heat, in kJ, evolved when a 72.0 g mixture containing equal parts of H₂and O₂, by mass, is burned?

Two solutions, 250.0 mL of 1.00 M CaCl₂(aq) and 250.0 mL of 1.00 M K₂SO₄(aq), are added to a calorimeter with a total heat capacity, after the solutions are added, of 1.25 kJ/°C and the temperature decreased by 2.40°C. Determine qrxn per mole of CaSO₄(s) formed in the reaction.

The complete combustion of propane, C₃H₈(g), is represented by the equation: C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(l) ΔH° = -2220 kJ How much heat is evolved in the complete combustion of 2.50 g C₃H₈(g)?

The complete combustion of 1 mole of nitrobenzene, C₆H₅NO₂, in a bomb calorimeter liberates 3088 kJ of heat and increases the temperature of the calorimeter assembly by 140.0 °C. What is the heat capacity of this bomb calorimeter?

Complete combustion of 75.0 g acetylene, C₂H₂, liberated 3750 kJ of heat. What is the heat of combustion, ΔHcomb, of acetylene?

Determine the enthalpy change in the following equation: 2 NH₃(g) → N₂(g) + 3 H₂(g) ΔH°f NH₃(g) = -46.11 kJ/mol

The combustion of 90.0 g of oxalic acid, C₂H₂O₄(s) in a bomb calorimeter whose heat capacity is 4.60 kJ/°C causes the temperature to rise from 25.0°C to 79.6°C. What is the heat of combustion of oxalic acid?