CHEM134 C003
LESSON 6 QUIZ
QUESTIONS AND ANSWERS | 2026 UPDATE
American Public University
Physical Chemistry: Thermodynamics, Kinetics, and Quantum Chemistry
25 Questions | 100 Points | 4 Sections
July 2026
, CHEM134 C003 Lesson 6 Quiz | APUS
Section 1: Chemical Thermodynamics & Phase Equilibria (Q1–Q7)
Q1: Which of the following correctly states the relationship between Gibbs free energy
change, enthalpy change, and entropy change?
A. ΔG = ΔH + T·ΔS
B. ΔG = ΔH × T·ΔS
C. ΔG = ΔH − T·ΔS
D. ΔG = T·ΔS − ΔH
Correct Answer: C
Rationale: The fundamental Gibbs free energy equation is ΔG = ΔH − T·ΔS. Option A incorrectly uses a
plus sign instead of minus. Option B incorrectly multiplies ΔH by T·ΔS. Option D reverses the terms.
Q2: A reaction has ΔH = −45.2 kJ/mol and ΔS = −120 J/(mol·K) at 298 K. Calculate ΔG and
determine if the reaction is spontaneous.
A. ΔG = −9.44 kJ/mol; spontaneous
B. ΔG = +80.6 kJ/mol; non-spontaneous
C. ΔG = −81.0 kJ/mol; spontaneous
D. ΔG = −9,440 kJ/mol; spontaneous
Correct Answer: A
Rationale: ΔG = ΔH − T·ΔS = −45,200 J/mol − 298 K × (−120 J/(mol·K)) = −45,200 + 35,760 = −9,440 J/mol =
−9.44 kJ/mol. Since ΔG < 0, the reaction is spontaneous. Option B results from using ΔS as +120 instead of
−120. Option C results from forgetting to convert kJ to J for ΔH. Option D results from not converting J to
kJ.
Q3: What does the chemical potential (μ) represent in a thermodynamic system?
A. The total internal energy of a system
B. The change in Gibbs free energy per mole of substance added to a system at constant T, P,
and composition
C. The maximum temperature at which a reaction proceeds
D. The enthalpy change per degree of temperature change
Correct Answer: B
Rationale: Chemical potential (μ) is defined as the partial molar Gibbs free energy: μ_i = (∂G/∂n_i) at
constant T, P, and n_j. Option A describes internal energy, not chemical potential. Option C is not a
definition of chemical potential. Option D describes heat capacity, not chemical potential.
Q4: Using the Clausius-Clapeyron equation, calculate the boiling point at 0.80 atm given
normal boiling point = 353 K and ΔH_vap = 38.6 kJ/mol. R = 8.314 J/(mol·K).
A. 341 K
B. 347 K
C. 359 K
D. 325 K
Correct Answer: B
Rationale: ln(P2/P1) = −(ΔH_vap/R)(1/T2 − 1/T1). ln(0.80/1.00) = −(38,600/8.314)(1/T2 − 1/353). −0.2231 =
−4,643.5 × (1/T2 − 1/353). 1/T2 − 1/353 = 0.00004805. 1/T2 = 0.002832 + 0.0000481 = 0.002880. T2 = 347 K.
Option A results from an arithmetic error in the slope calculation. Option C would be for P > 1 atm
(wrong direction). Option D results from sign error in the equation.
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LESSON 6 QUIZ
QUESTIONS AND ANSWERS | 2026 UPDATE
American Public University
Physical Chemistry: Thermodynamics, Kinetics, and Quantum Chemistry
25 Questions | 100 Points | 4 Sections
July 2026
, CHEM134 C003 Lesson 6 Quiz | APUS
Section 1: Chemical Thermodynamics & Phase Equilibria (Q1–Q7)
Q1: Which of the following correctly states the relationship between Gibbs free energy
change, enthalpy change, and entropy change?
A. ΔG = ΔH + T·ΔS
B. ΔG = ΔH × T·ΔS
C. ΔG = ΔH − T·ΔS
D. ΔG = T·ΔS − ΔH
Correct Answer: C
Rationale: The fundamental Gibbs free energy equation is ΔG = ΔH − T·ΔS. Option A incorrectly uses a
plus sign instead of minus. Option B incorrectly multiplies ΔH by T·ΔS. Option D reverses the terms.
Q2: A reaction has ΔH = −45.2 kJ/mol and ΔS = −120 J/(mol·K) at 298 K. Calculate ΔG and
determine if the reaction is spontaneous.
A. ΔG = −9.44 kJ/mol; spontaneous
B. ΔG = +80.6 kJ/mol; non-spontaneous
C. ΔG = −81.0 kJ/mol; spontaneous
D. ΔG = −9,440 kJ/mol; spontaneous
Correct Answer: A
Rationale: ΔG = ΔH − T·ΔS = −45,200 J/mol − 298 K × (−120 J/(mol·K)) = −45,200 + 35,760 = −9,440 J/mol =
−9.44 kJ/mol. Since ΔG < 0, the reaction is spontaneous. Option B results from using ΔS as +120 instead of
−120. Option C results from forgetting to convert kJ to J for ΔH. Option D results from not converting J to
kJ.
Q3: What does the chemical potential (μ) represent in a thermodynamic system?
A. The total internal energy of a system
B. The change in Gibbs free energy per mole of substance added to a system at constant T, P,
and composition
C. The maximum temperature at which a reaction proceeds
D. The enthalpy change per degree of temperature change
Correct Answer: B
Rationale: Chemical potential (μ) is defined as the partial molar Gibbs free energy: μ_i = (∂G/∂n_i) at
constant T, P, and n_j. Option A describes internal energy, not chemical potential. Option C is not a
definition of chemical potential. Option D describes heat capacity, not chemical potential.
Q4: Using the Clausius-Clapeyron equation, calculate the boiling point at 0.80 atm given
normal boiling point = 353 K and ΔH_vap = 38.6 kJ/mol. R = 8.314 J/(mol·K).
A. 341 K
B. 347 K
C. 359 K
D. 325 K
Correct Answer: B
Rationale: ln(P2/P1) = −(ΔH_vap/R)(1/T2 − 1/T1). ln(0.80/1.00) = −(38,600/8.314)(1/T2 − 1/353). −0.2231 =
−4,643.5 × (1/T2 − 1/353). 1/T2 − 1/353 = 0.00004805. 1/T2 = 0.002832 + 0.0000481 = 0.002880. T2 = 347 K.
Option A results from an arithmetic error in the slope calculation. Option C would be for P > 1 atm
(wrong direction). Option D results from sign error in the equation.
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