CHEM 1212 PRINCIPLES OF CHEMISTRY II (PDF) | 2026
EXAM QUESTIONS AND ANSWERS + RATIONALES | STUDY
GUIDE | 100% CORRECT
1. Which of the following best describes the primary focus of chemical kinetics?
A) The energy changes that occur during a chemical reaction
B) The extent to which a reaction proceeds to completion
C) The speed or rate at which a chemical reaction occurs
D) The stability of products relative to reactants
Correct Answer: C) The speed or rate at which a chemical reaction occurs
Rationale: Kinetics addresses the question "how fast do reactions go?" and focuses on reaction
rates and the factors that influence them . Thermodynamics, in contrast, addresses the extent and
spontaneity of reactions. Rate is defined as the change in concentration per unit time .
2. For the reaction rate expression, rate = k[A]^x[B]^y, what is the overall order of the reaction if
x = 2 and y = 1?
A) 1
B) 2
C) 3
D) Cannot be determined from the information given
Correct Answer: C) 3
Rationale: The overall order of a reaction is the sum of the individual orders with respect to
each reactant. If the reaction is second order with respect to A (x=2) and first order with respect
to B (y=1), the overall order is 2 + 1 = 3 .
3. Using the following data, what are the values of the exponents in the rate expression, rate =
k[A]^x[B]^y?
Experiment [A] (M) [B] (M) Rate (M/sec)
1 0.050 0.050 0.062
2 0.050 0.100 0.123
3 0.100 0.100 0.491
A) x=1, y=1
B) x=2, y=1
C) x=1, y=2
D) x=2, y=2
,Correct Answer: B) x=2, y=1
Rationale: Comparing Experiments 1 and 2, [A] is constant while [B] doubles and the rate
approximately doubles, so y=1. Comparing Experiments 2 and 3, [B] is constant while [A]
doubles and the rate increases by a factor of approximately 4 (0.491/0.123 ≈ 4), so x=2 .
4. What is the effect of a catalyst on a chemical reaction?
A) It increases the temperature of the reaction
B) It shifts the equilibrium position to favor products
C) It lowers the activation energy of the reaction
D) It increases the concentration of reactants
Correct Answer: C) It lowers the activation energy of the reaction
Rationale: A catalyst provides an alternative reaction pathway with a lower activation energy,
thereby increasing the rate of the reaction without being consumed . It does not affect the
equilibrium position or the thermodynamics of the reaction.
5. According to the Arrhenius definition, an acid is a substance that:
A) Produces OH⁻ ions when dissolved in water
B) Produces H₃O⁺ ions when dissolved in water
C) Accepts a proton from another substance
D) Donates a pair of electrons
Correct Answer: B) Produces H₃O⁺ ions when dissolved in water
Rationale: The Arrhenius definition states that an acid produces H₃O⁺ (hydronium ions) when
dissolved in water, while a base produces OH⁻ (hydroxide ions) . The Brønsted-Lowry definition
is broader, defining acids as proton donors and bases as proton acceptors.
6. Which of the following factors can change the rate of a chemical reaction?
A) Temperature
B) Reactant concentration
C) Addition of a catalyst
D) All of the above
Correct Answer: D) All of the above
Rationale: Reaction rate can be affected by temperature (increasing temperature generally
increases rate), reactant concentration (higher concentration typically increases rate), and the
presence of a catalyst (which lowers activation energy) .
7. Which of the following would be expected to affect the INITIAL rate of a chemical reaction?
A) Removing some products
B) Increasing the temperature
C) Adding a catalyst after the reaction has started
D) Changing the color of the solution
Correct Answer: B) Increasing the temperature
, Rationale: The initial rate depends on reactant concentrations, temperature, and the presence of
catalysts. Removing products does not affect the initial rate because products are not present
initially .
8. What is the definition of entropy (S)?
A) The heat content of a system at constant pressure
B) A quantitative measure of disorder or randomness
C) The energy available to do work
D) The measure of the strength of an acid
Correct Answer: B) A quantitative measure of disorder or randomness
Rationale: Entropy (S) is a thermodynamic function that quantifies the degree of disorder or
randomness in a system. The second law of thermodynamics states that the entropy of the
universe increases for spontaneous processes .
9. Which of the following changes would result in an INCREASE in entropy?
A) Liquid → Solid
B) Gas → Liquid
C) Solid → Liquid
D) Gas → Solid
Correct Answer: C) Solid → Liquid
Rationale: Entropy increases when a substance transitions to a state with greater molecular
motion and disorder: solid → liquid → gas. The liquid to gas transition represents a significant
increase in entropy .
10. For a spontaneous reaction, what is the sign of ΔG?
A) ΔG = 0
B) ΔG > 0
C) ΔG < 0
D) ΔG cannot be determined
Correct Answer: C) ΔG < 0
Rationale: A spontaneous reaction has a negative change in Gibbs free energy (ΔG < 0). At
equilibrium, ΔG = 0. A positive ΔG indicates a non-spontaneous reaction .
11. The First Law of Thermodynamics states that:
A) Energy cannot be changed from one form to another without a loss of usable energy
B) Energy can be transferred and transformed, but it cannot be created or destroyed
C) The entropy of the universe always increases for spontaneous processes
D) The heat content of a system at constant pressure is constant
Correct Answer: B) Energy can be transferred and transformed, but it cannot be created or
destroyed
EXAM QUESTIONS AND ANSWERS + RATIONALES | STUDY
GUIDE | 100% CORRECT
1. Which of the following best describes the primary focus of chemical kinetics?
A) The energy changes that occur during a chemical reaction
B) The extent to which a reaction proceeds to completion
C) The speed or rate at which a chemical reaction occurs
D) The stability of products relative to reactants
Correct Answer: C) The speed or rate at which a chemical reaction occurs
Rationale: Kinetics addresses the question "how fast do reactions go?" and focuses on reaction
rates and the factors that influence them . Thermodynamics, in contrast, addresses the extent and
spontaneity of reactions. Rate is defined as the change in concentration per unit time .
2. For the reaction rate expression, rate = k[A]^x[B]^y, what is the overall order of the reaction if
x = 2 and y = 1?
A) 1
B) 2
C) 3
D) Cannot be determined from the information given
Correct Answer: C) 3
Rationale: The overall order of a reaction is the sum of the individual orders with respect to
each reactant. If the reaction is second order with respect to A (x=2) and first order with respect
to B (y=1), the overall order is 2 + 1 = 3 .
3. Using the following data, what are the values of the exponents in the rate expression, rate =
k[A]^x[B]^y?
Experiment [A] (M) [B] (M) Rate (M/sec)
1 0.050 0.050 0.062
2 0.050 0.100 0.123
3 0.100 0.100 0.491
A) x=1, y=1
B) x=2, y=1
C) x=1, y=2
D) x=2, y=2
,Correct Answer: B) x=2, y=1
Rationale: Comparing Experiments 1 and 2, [A] is constant while [B] doubles and the rate
approximately doubles, so y=1. Comparing Experiments 2 and 3, [B] is constant while [A]
doubles and the rate increases by a factor of approximately 4 (0.491/0.123 ≈ 4), so x=2 .
4. What is the effect of a catalyst on a chemical reaction?
A) It increases the temperature of the reaction
B) It shifts the equilibrium position to favor products
C) It lowers the activation energy of the reaction
D) It increases the concentration of reactants
Correct Answer: C) It lowers the activation energy of the reaction
Rationale: A catalyst provides an alternative reaction pathway with a lower activation energy,
thereby increasing the rate of the reaction without being consumed . It does not affect the
equilibrium position or the thermodynamics of the reaction.
5. According to the Arrhenius definition, an acid is a substance that:
A) Produces OH⁻ ions when dissolved in water
B) Produces H₃O⁺ ions when dissolved in water
C) Accepts a proton from another substance
D) Donates a pair of electrons
Correct Answer: B) Produces H₃O⁺ ions when dissolved in water
Rationale: The Arrhenius definition states that an acid produces H₃O⁺ (hydronium ions) when
dissolved in water, while a base produces OH⁻ (hydroxide ions) . The Brønsted-Lowry definition
is broader, defining acids as proton donors and bases as proton acceptors.
6. Which of the following factors can change the rate of a chemical reaction?
A) Temperature
B) Reactant concentration
C) Addition of a catalyst
D) All of the above
Correct Answer: D) All of the above
Rationale: Reaction rate can be affected by temperature (increasing temperature generally
increases rate), reactant concentration (higher concentration typically increases rate), and the
presence of a catalyst (which lowers activation energy) .
7. Which of the following would be expected to affect the INITIAL rate of a chemical reaction?
A) Removing some products
B) Increasing the temperature
C) Adding a catalyst after the reaction has started
D) Changing the color of the solution
Correct Answer: B) Increasing the temperature
, Rationale: The initial rate depends on reactant concentrations, temperature, and the presence of
catalysts. Removing products does not affect the initial rate because products are not present
initially .
8. What is the definition of entropy (S)?
A) The heat content of a system at constant pressure
B) A quantitative measure of disorder or randomness
C) The energy available to do work
D) The measure of the strength of an acid
Correct Answer: B) A quantitative measure of disorder or randomness
Rationale: Entropy (S) is a thermodynamic function that quantifies the degree of disorder or
randomness in a system. The second law of thermodynamics states that the entropy of the
universe increases for spontaneous processes .
9. Which of the following changes would result in an INCREASE in entropy?
A) Liquid → Solid
B) Gas → Liquid
C) Solid → Liquid
D) Gas → Solid
Correct Answer: C) Solid → Liquid
Rationale: Entropy increases when a substance transitions to a state with greater molecular
motion and disorder: solid → liquid → gas. The liquid to gas transition represents a significant
increase in entropy .
10. For a spontaneous reaction, what is the sign of ΔG?
A) ΔG = 0
B) ΔG > 0
C) ΔG < 0
D) ΔG cannot be determined
Correct Answer: C) ΔG < 0
Rationale: A spontaneous reaction has a negative change in Gibbs free energy (ΔG < 0). At
equilibrium, ΔG = 0. A positive ΔG indicates a non-spontaneous reaction .
11. The First Law of Thermodynamics states that:
A) Energy cannot be changed from one form to another without a loss of usable energy
B) Energy can be transferred and transformed, but it cannot be created or destroyed
C) The entropy of the universe always increases for spontaneous processes
D) The heat content of a system at constant pressure is constant
Correct Answer: B) Energy can be transferred and transformed, but it cannot be created or
destroyed
