PORTAGE LEARNING CHEM 103 (GENERAL CHEMISTRY I) MODULE 7 EXAM
PRACTICE — COMPREHENSIVE THERMOCHEMISTRY STUDY GUIDE, FULL
TESTBANK & 150 ADVANCED PRACTICE QUESTIONS WITH 100% CORRECT
ANSWERS AND RATIONALES — 2026/2027 LATEST UPDATE
TABLE OF CONTENTS
i. Energy, Work, Heat, and Thermodynamic Systems
ii. Exothermic and Endothermic Processes
iii. Specific Heat and Heat Capacity
iv. Calorimetry and Experimental Heat Transfer
v. Enthalpy and Enthalpy Changes
vi. Thermochemical Equations
vii. Hess’s Law and Reaction Enthalpy
viii. Standard Enthalpies of Formation
ix. Bond Energy and Bond Dissociation
x. Ionic and Covalent Bond Energetics
xi. Advanced Thermochemical Calculations
xii. Experimental Analysis, Error, and Energy Efficiency
xiii. Integrated and Applied Thermochemistry Problems
DESCRIPTION
This comprehensive practice resource prepares students for advanced study of CHEM
103 Module 7 thermochemistry. It covers energy transfer, heat, work, calorimetry,
specific heat, heat capacity, enthalpy, thermochemical equations, Hess’s law, standard
enthalpies of formation, bond energies, and ionic and covalent bonding energetics.
The questions emphasize quantitative reasoning, interpretation of experimental data,
multi-step calculations, energy-flow analysis, and application of chemical principles to
unfamiliar scenarios. It is designed for students seeking rigorous exam preparation,
conceptual mastery, and stronger problem-solving skills. It contains 100+ practice
questions and answers with rationales for systematic review and exam preparation
(purchase and instantly get a downloadable and editable pdf).
ENERGY, HEAT, AND THERMOCHEMISTRY
Question 1
A closed chemical system absorbs 425 J of heat from its surroundings while
simultaneously performing 175 J of work on those surroundings. What is the change
in internal energy?
A. −600 J
B. −250 J
,C. +250 J
D. +600 J
🔴 Correct Answer: C. +250 J
🔵 Explanation: Using ΔE = q + w, heat entering the system gives q = +425 J, while
work performed by the system gives w = −175 J. Thus ΔE = 425 − 175 = +250 J.
Question 2
A reaction occurs in an insulated container. The temperature of the reacting mixture
decreases substantially. Which interpretation is most appropriate?
A. The reaction is necessarily exothermic.
B. The reaction absorbs thermal energy from its surroundings.
C. The reaction releases thermal energy into the surroundings.
D. The reaction cannot involve an enthalpy change.
🔴 Correct Answer: B. The reaction absorbs thermal energy from its surroundings.
🔵 Explanation: A temperature decrease of the reaction mixture indicates that energy is
being absorbed by the reacting system. Such a process is consistent with an endothermic
reaction.
Question 3
A student defines the system as the reacting chemicals in a coffee-cup calorimeter.
Which entity is part of the surroundings?
A. Only the products
B. Only the reactants
C. The solution and calorimeter
D. The chemical bonds being broken
🔴 Correct Answer: C. The solution and calorimeter
🔵 Explanation: The surroundings include everything outside the defined chemical
system. In calorimetry, the solution, calorimeter, and surrounding environment can
exchange energy with the reacting chemicals.
Question 4
A reaction has ΔH = −86.4 kJ mol⁻¹. Which statement is necessarily correct for the
reaction as written?
A. The reaction absorbs 86.4 kJ per mole.
B. The reaction releases 86.4 kJ per mole.
C. The reaction has zero energy transfer.
D. The products contain more enthalpy than the reactants.
,🔴 Correct Answer: B. The reaction releases 86.4 kJ per mole.
🔵 Explanation: A negative enthalpy change indicates an exothermic process. Therefore,
86.4 kJ of heat is released per mole of reaction as written.
Question 5
Which change would most directly increase the thermal energy transferred during
heating if q = mcΔT?
A. Decreasing mass while maintaining ΔT
B. Decreasing specific heat while maintaining mass and ΔT
C. Increasing mass while maintaining specific heat and ΔT
D. Decreasing ΔT while maintaining mass and specific heat
🔴 Correct Answer: C. Increasing mass while maintaining specific heat and ΔT
🔵 Explanation: Heat is directly proportional to mass, specific heat, and temperature
change. Increasing mass therefore increases q when the other variables remain constant.
Question 6
A 150.0-g metal sample absorbs 3.60 kJ while its temperature rises from 20.0°C to
80.0°C. What is its specific heat?
A. 0.0400 J g⁻¹ °C⁻¹
B. 0.400 J g⁻¹ °C⁻¹
C. 2.40 J g⁻¹ °C⁻¹
D. 4.00 J g⁻¹ °C⁻¹
🔴 Correct Answer: B. 0.400 J g⁻¹ °C⁻¹
🔵 Explanation: q = mcΔT, so c = 3600 J ÷ [(150.0 g)(60.0°C)] = 0.400 J g⁻¹ °C⁻¹.
Question 7
A sample undergoes a temperature increase of 18.5°C. Which temperature difference
should be used in q = mcΔT?
A. 18.5 K only
B. 291.65 K
C. 18.5°C
D. 255.0°C
🔴 Correct Answer: C. 18.5°C
🔵 Explanation: Temperature differences have identical numerical magnitudes in
Celsius and Kelvin. Therefore ΔT = 18.5°C is appropriate.
Question 8
A substance has a high specific heat capacity. Compared with a substance of identical
mass receiving the same quantity of heat, it will generally:
, A. Experience a larger temperature increase
B. Experience a smaller temperature increase
C. Undergo no temperature change
D. Release more heat
🔴 Correct Answer: B. Experience a smaller temperature increase
🔵 Explanation: From ΔT = q/(mc), a larger specific heat produces a smaller
temperature change for the same heat input and mass.
Question 9
A 50.0-g metal at 95.0°C is placed in 100.0 g of water at 22.0°C. The final temperature
is 28.0°C. Neglecting heat loss, what relationship must hold?
A. qmetal = qwater
B. qmetal = 0
C. qmetal = −qwater
D. qmetal + qwater > 0
🔴 Correct Answer: C. qmetal = −qwater
🔵 Explanation: Conservation of energy requires heat lost by the hot metal to equal
heat gained by the cooler water. Their heat changes therefore have equal magnitudes
and opposite signs.
Question 10
In an ideal isolated calorimetry experiment, the measured heat gained by the water is
+4.25 kJ. What is the heat change of the reaction?
A. +4.25 kJ
B. −4.25 kJ
C. 0 kJ
D. +8.50 kJ
🔴 Correct Answer: B. −4.25 kJ
🔵 Explanation: Energy conservation requires qreaction + qwater = 0. Therefore
qreaction = −4.25 kJ.
Question 11
A process has q = +72 kJ and w = −25 kJ. What is ΔE?
A. −97 kJ
B. −47 kJ
C. +47 kJ
D. +97 kJ
PRACTICE — COMPREHENSIVE THERMOCHEMISTRY STUDY GUIDE, FULL
TESTBANK & 150 ADVANCED PRACTICE QUESTIONS WITH 100% CORRECT
ANSWERS AND RATIONALES — 2026/2027 LATEST UPDATE
TABLE OF CONTENTS
i. Energy, Work, Heat, and Thermodynamic Systems
ii. Exothermic and Endothermic Processes
iii. Specific Heat and Heat Capacity
iv. Calorimetry and Experimental Heat Transfer
v. Enthalpy and Enthalpy Changes
vi. Thermochemical Equations
vii. Hess’s Law and Reaction Enthalpy
viii. Standard Enthalpies of Formation
ix. Bond Energy and Bond Dissociation
x. Ionic and Covalent Bond Energetics
xi. Advanced Thermochemical Calculations
xii. Experimental Analysis, Error, and Energy Efficiency
xiii. Integrated and Applied Thermochemistry Problems
DESCRIPTION
This comprehensive practice resource prepares students for advanced study of CHEM
103 Module 7 thermochemistry. It covers energy transfer, heat, work, calorimetry,
specific heat, heat capacity, enthalpy, thermochemical equations, Hess’s law, standard
enthalpies of formation, bond energies, and ionic and covalent bonding energetics.
The questions emphasize quantitative reasoning, interpretation of experimental data,
multi-step calculations, energy-flow analysis, and application of chemical principles to
unfamiliar scenarios. It is designed for students seeking rigorous exam preparation,
conceptual mastery, and stronger problem-solving skills. It contains 100+ practice
questions and answers with rationales for systematic review and exam preparation
(purchase and instantly get a downloadable and editable pdf).
ENERGY, HEAT, AND THERMOCHEMISTRY
Question 1
A closed chemical system absorbs 425 J of heat from its surroundings while
simultaneously performing 175 J of work on those surroundings. What is the change
in internal energy?
A. −600 J
B. −250 J
,C. +250 J
D. +600 J
🔴 Correct Answer: C. +250 J
🔵 Explanation: Using ΔE = q + w, heat entering the system gives q = +425 J, while
work performed by the system gives w = −175 J. Thus ΔE = 425 − 175 = +250 J.
Question 2
A reaction occurs in an insulated container. The temperature of the reacting mixture
decreases substantially. Which interpretation is most appropriate?
A. The reaction is necessarily exothermic.
B. The reaction absorbs thermal energy from its surroundings.
C. The reaction releases thermal energy into the surroundings.
D. The reaction cannot involve an enthalpy change.
🔴 Correct Answer: B. The reaction absorbs thermal energy from its surroundings.
🔵 Explanation: A temperature decrease of the reaction mixture indicates that energy is
being absorbed by the reacting system. Such a process is consistent with an endothermic
reaction.
Question 3
A student defines the system as the reacting chemicals in a coffee-cup calorimeter.
Which entity is part of the surroundings?
A. Only the products
B. Only the reactants
C. The solution and calorimeter
D. The chemical bonds being broken
🔴 Correct Answer: C. The solution and calorimeter
🔵 Explanation: The surroundings include everything outside the defined chemical
system. In calorimetry, the solution, calorimeter, and surrounding environment can
exchange energy with the reacting chemicals.
Question 4
A reaction has ΔH = −86.4 kJ mol⁻¹. Which statement is necessarily correct for the
reaction as written?
A. The reaction absorbs 86.4 kJ per mole.
B. The reaction releases 86.4 kJ per mole.
C. The reaction has zero energy transfer.
D. The products contain more enthalpy than the reactants.
,🔴 Correct Answer: B. The reaction releases 86.4 kJ per mole.
🔵 Explanation: A negative enthalpy change indicates an exothermic process. Therefore,
86.4 kJ of heat is released per mole of reaction as written.
Question 5
Which change would most directly increase the thermal energy transferred during
heating if q = mcΔT?
A. Decreasing mass while maintaining ΔT
B. Decreasing specific heat while maintaining mass and ΔT
C. Increasing mass while maintaining specific heat and ΔT
D. Decreasing ΔT while maintaining mass and specific heat
🔴 Correct Answer: C. Increasing mass while maintaining specific heat and ΔT
🔵 Explanation: Heat is directly proportional to mass, specific heat, and temperature
change. Increasing mass therefore increases q when the other variables remain constant.
Question 6
A 150.0-g metal sample absorbs 3.60 kJ while its temperature rises from 20.0°C to
80.0°C. What is its specific heat?
A. 0.0400 J g⁻¹ °C⁻¹
B. 0.400 J g⁻¹ °C⁻¹
C. 2.40 J g⁻¹ °C⁻¹
D. 4.00 J g⁻¹ °C⁻¹
🔴 Correct Answer: B. 0.400 J g⁻¹ °C⁻¹
🔵 Explanation: q = mcΔT, so c = 3600 J ÷ [(150.0 g)(60.0°C)] = 0.400 J g⁻¹ °C⁻¹.
Question 7
A sample undergoes a temperature increase of 18.5°C. Which temperature difference
should be used in q = mcΔT?
A. 18.5 K only
B. 291.65 K
C. 18.5°C
D. 255.0°C
🔴 Correct Answer: C. 18.5°C
🔵 Explanation: Temperature differences have identical numerical magnitudes in
Celsius and Kelvin. Therefore ΔT = 18.5°C is appropriate.
Question 8
A substance has a high specific heat capacity. Compared with a substance of identical
mass receiving the same quantity of heat, it will generally:
, A. Experience a larger temperature increase
B. Experience a smaller temperature increase
C. Undergo no temperature change
D. Release more heat
🔴 Correct Answer: B. Experience a smaller temperature increase
🔵 Explanation: From ΔT = q/(mc), a larger specific heat produces a smaller
temperature change for the same heat input and mass.
Question 9
A 50.0-g metal at 95.0°C is placed in 100.0 g of water at 22.0°C. The final temperature
is 28.0°C. Neglecting heat loss, what relationship must hold?
A. qmetal = qwater
B. qmetal = 0
C. qmetal = −qwater
D. qmetal + qwater > 0
🔴 Correct Answer: C. qmetal = −qwater
🔵 Explanation: Conservation of energy requires heat lost by the hot metal to equal
heat gained by the cooler water. Their heat changes therefore have equal magnitudes
and opposite signs.
Question 10
In an ideal isolated calorimetry experiment, the measured heat gained by the water is
+4.25 kJ. What is the heat change of the reaction?
A. +4.25 kJ
B. −4.25 kJ
C. 0 kJ
D. +8.50 kJ
🔴 Correct Answer: B. −4.25 kJ
🔵 Explanation: Energy conservation requires qreaction + qwater = 0. Therefore
qreaction = −4.25 kJ.
Question 11
A process has q = +72 kJ and w = −25 kJ. What is ΔE?
A. −97 kJ
B. −47 kJ
C. +47 kJ
D. +97 kJ
