UNE General Chemistry 2 Exam Questions and Answers 2025/2026 Ultimate Mega
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Question 1: Which of the following factors does NOT affect the rate of a chemical reaction?
A. Temperature
B. Concentration of reactants
C. Presence of a catalyst
D. Enthalpy change of the reaction
CORRECT ANSWER: D. Enthalpy change of the reaction
RATIONALE: The rate of a chemical reaction is influenced by temperature, concentration, surface area,
and catalysts, which affect the frequency or energy of molecular collisions. Enthalpy change (ΔH) is a
thermodynamic property that describes the heat absorbed or released during a reaction but does not
directly influence how fast the reaction proceeds.
Question 2: For a first-order reaction, the half-life is:
A. Dependent on the initial concentration of reactant
B. Independent of the initial concentration of reactant
C. Directly proportional to the rate constant
D. Equal to the time required for complete reaction
CORRECT ANSWER: B. Independent of the initial concentration of reactant
RATIONALE: For a first-order reaction, the half-life equation is t₁/₂ = 0.693/k, where k is the rate
constant. This equation shows that half-life depends only on the rate constant and is independent of the
initial reactant concentration, distinguishing first-order kinetics from zero- or second-order reactions.
Question 3: The rate law for a reaction is determined to be Rate = k[A]²[B]. What is the overall order
of this reaction?
A. First order
B. Second order
C. Third order
D. Fourth order
CORRECT ANSWER: C. Third order
RATIONALE: The overall order of a reaction is the sum of the exponents in the rate law. Here, the
exponent for [A] is 2 and for [B] is 1, so the overall order is 2 + 1 = 3, making it a third-order reaction.
Question 4: Which statement best describes the activation energy of a reaction?
A. The energy released when products form
B. The minimum energy required for reactants to form products
,C. The difference in energy between reactants and products
D. The energy required to break all bonds in the reactants
CORRECT ANSWER: B. The minimum energy required for reactants to form products
RATIONALE: Activation energy (Eₐ) is the minimum energy barrier that reactant molecules must
overcome to be converted into products. It is not the energy released (that relates to ΔH), nor the total
bond-breaking energy, but specifically the threshold energy for successful collisions.
Question 5: In the Arrhenius equation k = Ae^(-Eₐ/RT), what does the symbol A represent?
A. Activation energy
B. Gas constant
C. Frequency factor
D. Absolute temperature
CORRECT ANSWER: C. Frequency factor
RATIONALE: In the Arrhenius equation, A is the frequency factor (or pre-exponential factor), which
represents the frequency of collisions with proper orientation for reaction. Eₐ is activation energy, R is
the gas constant, and T is absolute temperature.
Question 6: A catalyst increases the rate of a chemical reaction by:
A. Increasing the enthalpy change of the reaction
B. Decreasing the activation energy of the reaction
C. Increasing the equilibrium constant
D. Shifting the equilibrium position toward products
CORRECT ANSWER: B. Decreasing the activation energy of the reaction
RATIONALE: Catalysts provide an alternative reaction pathway with a lower activation energy, allowing
more reactant molecules to possess sufficient energy to react at a given temperature. Catalysts do not
alter ΔH, K_eq, or equilibrium position; they only speed up the attainment of equilibrium.
Question 7: For the reaction 2NO(g) + O₂(g) → 2NO₂(g), if the rate of disappearance of NO is 0.066
M/s, what is the rate of appearance of NO₂?
A. 0.033 M/s
B. 0.066 M/s
C. 0.132 M/s
D. 0.198 M/s
CORRECT ANSWER: B. 0.066 M/s
RATIONALE: From the stoichiometry, 2 moles of NO produce 2 moles of NO₂, so the rate of
disappearance of NO equals the rate of appearance of NO₂. Mathematically, -½Δ[NO]/Δt = +½Δ[NO₂]/Δt,
therefore Δ[NO₂]/Δt = -Δ[NO]/Δt = 0.066 M/s.
Question 8: Which of the following is true for a zero-order reaction?
,A. A plot of [A] versus time is linear with negative slope
B. A plot of ln[A] versus time is linear with negative slope
C. A plot of 1/[A] versus time is linear with positive slope
D. The half-life increases as initial concentration decreases
CORRECT ANSWER: A. A plot of [A] versus time is linear with negative slope
RATIONALE: For a zero-order reaction, the integrated rate law is [A]_t = -kt + [A]_₀, which is linear in
the form y = mx + b. A plot of concentration versus time yields a straight line with slope = -k. Options B
and C describe first- and second-order reactions, respectively.
Question 9: The rate constant for a reaction doubles when the temperature increases from 300 K to
310 K. What is the approximate activation energy?
A. 25 kJ/mol
B. 53 kJ/mol
C. 75 kJ/mol
D. 100 kJ/mol
CORRECT ANSWER: B. 53 kJ/mol
RATIONALE: Using the two-point Arrhenius equation: ln(k₂/k₁) = (Eₐ/R)(1/T₁ - 1/T₂). With k₂/k₁ = 2, R =
8.314 J/mol·K, T₁ = 300 K, T₂ = 310 K: ln(2) = (Eₐ/8.314)(1/300 - 1/310). Solving gives Eₐ ≈ 53,000 J/mol =
53 kJ/mol.
Question 10: Which experimental method is MOST appropriate for determining the rate law of a
reaction?
A. Measuring equilibrium concentrations
B. Using the method of initial rates
C. Calculating ΔG° from standard tables
D. Determining the enthalpy change via calorimetry
CORRECT ANSWER: B. Using the method of initial rates
RATIONALE: The method of initial rates involves measuring the initial reaction rate at different initial
reactant concentrations while holding other variables constant. This allows determination of reaction
orders with respect to each reactant and the rate constant, which defines the rate law.
Question 11: In a reaction mechanism, the rate-determining step is:
A. The fastest step in the mechanism
B. The step with the lowest activation energy
C. The slowest step in the mechanism
D. The step that occurs at equilibrium
CORRECT ANSWER: C. The slowest step in the mechanism
, RATIONALE: The rate-determining step (RDS) is the slowest elementary step in a reaction mechanism.
Because the overall reaction cannot proceed faster than its slowest step, the RDS governs the observed
rate law and kinetics of the overall reaction.
Question 12: For the elementary reaction A + 2B → C, what is the molecularity?
A. Unimolecular
B. Bimolecular
C. Termolecular
D. Quadmolecular
CORRECT ANSWER: C. Termolecular
RATIONALE: Molecularity refers to the number of reactant particles colliding in an elementary step.
Here, one A molecule and two B molecules (total of three particles) collide simultaneously, making this a
termolecular elementary reaction.
Question 13: Which of the following statements about reaction intermediates is TRUE?
A. Intermediates appear in the overall balanced equation
B. Intermediates are consumed in one step and produced in a later step
C. Intermediates are present at the start of the reaction
D. Intermediates increase the activation energy of the reaction
CORRECT ANSWER: B. Intermediates are consumed in one step and produced in a later step
RATIONALE: Reaction intermediates are species that are formed in one elementary step of a
mechanism and consumed in a subsequent step. They do not appear in the overall balanced equation
because they cancel out when steps are summed, and they are not present initially.
Question 14: A reaction has the rate law Rate = k[A][B]². If [A] is doubled and [B] is halved, the new
rate will be:
A. One-fourth the original rate
B. One-half the original rate
C. Equal to the original rate
D. Twice the original rate
CORRECT ANSWER: B. One-half the original rate
RATIONALE: Original rate = k[A][B]². New rate = k[2A][0.5B]² = k(2[A])(0.25[B]²) = 0.5k[A][B]².
Therefore, the new rate is one-half the original rate.
Question 15: Which graph would yield a straight line for a second-order reaction with one reactant?
A. [A] vs. time
B. ln[A] vs. time
C. 1/[A] vs. time
D. [A]² vs. time
CORRECT ANSWER: C. 1/[A] vs. time
Bundle | Complete GEN CHEM II Study Guide, Chemical Equilibrium, Thermodynamics,
Kinetics, Acids and Bases, Electrochemistry, Solutions, Molecular Chemistry, Practice
Test Bank with Verified Answers, Detailed Step-by-Step Solutions, and Proven Exam
Passing Strategies for University of New England Students
Question 1: Which of the following factors does NOT affect the rate of a chemical reaction?
A. Temperature
B. Concentration of reactants
C. Presence of a catalyst
D. Enthalpy change of the reaction
CORRECT ANSWER: D. Enthalpy change of the reaction
RATIONALE: The rate of a chemical reaction is influenced by temperature, concentration, surface area,
and catalysts, which affect the frequency or energy of molecular collisions. Enthalpy change (ΔH) is a
thermodynamic property that describes the heat absorbed or released during a reaction but does not
directly influence how fast the reaction proceeds.
Question 2: For a first-order reaction, the half-life is:
A. Dependent on the initial concentration of reactant
B. Independent of the initial concentration of reactant
C. Directly proportional to the rate constant
D. Equal to the time required for complete reaction
CORRECT ANSWER: B. Independent of the initial concentration of reactant
RATIONALE: For a first-order reaction, the half-life equation is t₁/₂ = 0.693/k, where k is the rate
constant. This equation shows that half-life depends only on the rate constant and is independent of the
initial reactant concentration, distinguishing first-order kinetics from zero- or second-order reactions.
Question 3: The rate law for a reaction is determined to be Rate = k[A]²[B]. What is the overall order
of this reaction?
A. First order
B. Second order
C. Third order
D. Fourth order
CORRECT ANSWER: C. Third order
RATIONALE: The overall order of a reaction is the sum of the exponents in the rate law. Here, the
exponent for [A] is 2 and for [B] is 1, so the overall order is 2 + 1 = 3, making it a third-order reaction.
Question 4: Which statement best describes the activation energy of a reaction?
A. The energy released when products form
B. The minimum energy required for reactants to form products
,C. The difference in energy between reactants and products
D. The energy required to break all bonds in the reactants
CORRECT ANSWER: B. The minimum energy required for reactants to form products
RATIONALE: Activation energy (Eₐ) is the minimum energy barrier that reactant molecules must
overcome to be converted into products. It is not the energy released (that relates to ΔH), nor the total
bond-breaking energy, but specifically the threshold energy for successful collisions.
Question 5: In the Arrhenius equation k = Ae^(-Eₐ/RT), what does the symbol A represent?
A. Activation energy
B. Gas constant
C. Frequency factor
D. Absolute temperature
CORRECT ANSWER: C. Frequency factor
RATIONALE: In the Arrhenius equation, A is the frequency factor (or pre-exponential factor), which
represents the frequency of collisions with proper orientation for reaction. Eₐ is activation energy, R is
the gas constant, and T is absolute temperature.
Question 6: A catalyst increases the rate of a chemical reaction by:
A. Increasing the enthalpy change of the reaction
B. Decreasing the activation energy of the reaction
C. Increasing the equilibrium constant
D. Shifting the equilibrium position toward products
CORRECT ANSWER: B. Decreasing the activation energy of the reaction
RATIONALE: Catalysts provide an alternative reaction pathway with a lower activation energy, allowing
more reactant molecules to possess sufficient energy to react at a given temperature. Catalysts do not
alter ΔH, K_eq, or equilibrium position; they only speed up the attainment of equilibrium.
Question 7: For the reaction 2NO(g) + O₂(g) → 2NO₂(g), if the rate of disappearance of NO is 0.066
M/s, what is the rate of appearance of NO₂?
A. 0.033 M/s
B. 0.066 M/s
C. 0.132 M/s
D. 0.198 M/s
CORRECT ANSWER: B. 0.066 M/s
RATIONALE: From the stoichiometry, 2 moles of NO produce 2 moles of NO₂, so the rate of
disappearance of NO equals the rate of appearance of NO₂. Mathematically, -½Δ[NO]/Δt = +½Δ[NO₂]/Δt,
therefore Δ[NO₂]/Δt = -Δ[NO]/Δt = 0.066 M/s.
Question 8: Which of the following is true for a zero-order reaction?
,A. A plot of [A] versus time is linear with negative slope
B. A plot of ln[A] versus time is linear with negative slope
C. A plot of 1/[A] versus time is linear with positive slope
D. The half-life increases as initial concentration decreases
CORRECT ANSWER: A. A plot of [A] versus time is linear with negative slope
RATIONALE: For a zero-order reaction, the integrated rate law is [A]_t = -kt + [A]_₀, which is linear in
the form y = mx + b. A plot of concentration versus time yields a straight line with slope = -k. Options B
and C describe first- and second-order reactions, respectively.
Question 9: The rate constant for a reaction doubles when the temperature increases from 300 K to
310 K. What is the approximate activation energy?
A. 25 kJ/mol
B. 53 kJ/mol
C. 75 kJ/mol
D. 100 kJ/mol
CORRECT ANSWER: B. 53 kJ/mol
RATIONALE: Using the two-point Arrhenius equation: ln(k₂/k₁) = (Eₐ/R)(1/T₁ - 1/T₂). With k₂/k₁ = 2, R =
8.314 J/mol·K, T₁ = 300 K, T₂ = 310 K: ln(2) = (Eₐ/8.314)(1/300 - 1/310). Solving gives Eₐ ≈ 53,000 J/mol =
53 kJ/mol.
Question 10: Which experimental method is MOST appropriate for determining the rate law of a
reaction?
A. Measuring equilibrium concentrations
B. Using the method of initial rates
C. Calculating ΔG° from standard tables
D. Determining the enthalpy change via calorimetry
CORRECT ANSWER: B. Using the method of initial rates
RATIONALE: The method of initial rates involves measuring the initial reaction rate at different initial
reactant concentrations while holding other variables constant. This allows determination of reaction
orders with respect to each reactant and the rate constant, which defines the rate law.
Question 11: In a reaction mechanism, the rate-determining step is:
A. The fastest step in the mechanism
B. The step with the lowest activation energy
C. The slowest step in the mechanism
D. The step that occurs at equilibrium
CORRECT ANSWER: C. The slowest step in the mechanism
, RATIONALE: The rate-determining step (RDS) is the slowest elementary step in a reaction mechanism.
Because the overall reaction cannot proceed faster than its slowest step, the RDS governs the observed
rate law and kinetics of the overall reaction.
Question 12: For the elementary reaction A + 2B → C, what is the molecularity?
A. Unimolecular
B. Bimolecular
C. Termolecular
D. Quadmolecular
CORRECT ANSWER: C. Termolecular
RATIONALE: Molecularity refers to the number of reactant particles colliding in an elementary step.
Here, one A molecule and two B molecules (total of three particles) collide simultaneously, making this a
termolecular elementary reaction.
Question 13: Which of the following statements about reaction intermediates is TRUE?
A. Intermediates appear in the overall balanced equation
B. Intermediates are consumed in one step and produced in a later step
C. Intermediates are present at the start of the reaction
D. Intermediates increase the activation energy of the reaction
CORRECT ANSWER: B. Intermediates are consumed in one step and produced in a later step
RATIONALE: Reaction intermediates are species that are formed in one elementary step of a
mechanism and consumed in a subsequent step. They do not appear in the overall balanced equation
because they cancel out when steps are summed, and they are not present initially.
Question 14: A reaction has the rate law Rate = k[A][B]². If [A] is doubled and [B] is halved, the new
rate will be:
A. One-fourth the original rate
B. One-half the original rate
C. Equal to the original rate
D. Twice the original rate
CORRECT ANSWER: B. One-half the original rate
RATIONALE: Original rate = k[A][B]². New rate = k[2A][0.5B]² = k(2[A])(0.25[B]²) = 0.5k[A][B]².
Therefore, the new rate is one-half the original rate.
Question 15: Which graph would yield a straight line for a second-order reaction with one reactant?
A. [A] vs. time
B. ln[A] vs. time
C. 1/[A] vs. time
D. [A]² vs. time
CORRECT ANSWER: C. 1/[A] vs. time
