CHEM 102 General Chemistry II
FINAL EXAM — 2026
Comprehensive Practice Examination
with Answer Keys and Detailed
Rationales
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) Standard enthalpy change (ΔH°) of the reaction
Answer: D
Rationale for A: Temperature increases kinetic energy and collision
frequency, directly increasing reaction rate.
Rationale for B: Higher concentrations increase collision frequency
between reactant molecules, accelerating the reaction.
Rationale for C: Catalysts lower activation energy, providing an alternative
pathway that increases reaction rate.
Rationale for D: ΔH° is a thermodynamic property indicating heat change; it
does not influence kinetics or reaction rate directly.
,2. For a first-order reaction, the half-life is:
A) Directly proportional to initial concentration
B) Inversely proportional to initial concentration
C) Independent of initial concentration
D) Equal to the rate constant
Answer: C
Rationale for A: This describes zero-order reactions, not first-order.
Rationale for B: This describes second-order reactions with one reactant.
Rationale for C: For first-order reactions, t½ = ln(2)/k, which contains no
concentration term.
Rationale for D: Half-life has units of time; rate constant for first-order has
units of time⁻¹; they are reciprocally related but not equal.
3. The rate law for the reaction A + B → C is determined to be rate =
k[A]²[B]. What is the overall order of the reaction?
A) 1
B) 2
C) 3
D) 4
Answer: C
Rationale for A: Order 1 would require exponents summing to 1 (e.g., [A]¹
or [B]¹).
Rationale for B: Order 2 would require exponents summing to 2 (e.g., [A]²
or [A][B]).
Rationale for C: Overall order = sum of exponents = 2 + 1 = 3.
Rationale for D: Order 4 would require exponents summing to 4, which is
not the case here.
4. Which statement about catalysts is TRUE?
,A) Catalysts are consumed in the reaction
B) Catalysts increase the equilibrium constant
C) Catalysts lower the activation energy for both forward and reverse
reactions
D) Catalysts shift equilibrium toward products
Answer: C
Rationale for A: Catalysts are regenerated at the end of the reaction; they
are not consumed.
Rationale for B: Equilibrium constant depends only on thermodynamics
(ΔG°); catalysts affect kinetics only.
Rationale for C: Catalysts provide an alternative pathway with lower Ea for
both directions, speeding up attainment of equilibrium.
Rationale for D: Catalysts do not change equilibrium position; they only
speed up how fast equilibrium is reached.
5. At equilibrium, which of the following is TRUE?
A) The forward and reverse reactions have stopped
B) Concentrations of reactants and products are equal
C) The rate of the forward reaction equals the rate of the reverse reaction
D) The equilibrium constant K equals 1
Answer: C
Rationale for A: Reactions continue at the molecular level; equilibrium is
dynamic, not static.
Rationale for B: Concentrations are constant but not necessarily equal;
ratio is fixed by K.
Rationale for C: This is the definition of dynamic equilibrium: rates are
equal, so no net change.
Rationale for D: K = 1 only when ΔG° = 0; most reactions have K ≠ 1 at
equilibrium.
, 6. For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = -92 kJ. Which change
will shift equilibrium to the RIGHT?
A) Increasing temperature
B) Decreasing pressure
C) Adding a catalyst
D) Removing NH₃ as it forms
Answer: D
Rationale for A: Reaction is exothermic; increasing temperature favors
endothermic (reverse) direction (Le Châtelier).
Rationale for B: Decreasing pressure favors side with more moles of gas (4
vs. 2), shifting equilibrium LEFT.
Rationale for C: Catalysts speed up both directions equally; no shift in
equilibrium position.
Rationale for D: Removing product reduces Q, making Q < K, so reaction
proceeds forward to restore equilibrium.
7. The equilibrium constant expression for 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) is:
A) K = [SO₃]/[SO₂][O₂]
B) K = [SO₃]²/[SO₂]²[O₂]
C) K = [SO₂]²[O₂]/[SO₃]²
D) K = [SO₃]²[O₂]/[SO₂]²
Answer: B
Rationale for A: Missing exponents from stoichiometric coefficients;
incorrect form.
Rationale for B: Correct: products over reactants, each raised to their
coefficient.
Rationale for C: This is the expression for the reverse reaction (1/K).
Rationale for D: Incorrect placement of [O₂]; it should be in the
denominator.
FINAL EXAM — 2026
Comprehensive Practice Examination
with Answer Keys and Detailed
Rationales
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) Standard enthalpy change (ΔH°) of the reaction
Answer: D
Rationale for A: Temperature increases kinetic energy and collision
frequency, directly increasing reaction rate.
Rationale for B: Higher concentrations increase collision frequency
between reactant molecules, accelerating the reaction.
Rationale for C: Catalysts lower activation energy, providing an alternative
pathway that increases reaction rate.
Rationale for D: ΔH° is a thermodynamic property indicating heat change; it
does not influence kinetics or reaction rate directly.
,2. For a first-order reaction, the half-life is:
A) Directly proportional to initial concentration
B) Inversely proportional to initial concentration
C) Independent of initial concentration
D) Equal to the rate constant
Answer: C
Rationale for A: This describes zero-order reactions, not first-order.
Rationale for B: This describes second-order reactions with one reactant.
Rationale for C: For first-order reactions, t½ = ln(2)/k, which contains no
concentration term.
Rationale for D: Half-life has units of time; rate constant for first-order has
units of time⁻¹; they are reciprocally related but not equal.
3. The rate law for the reaction A + B → C is determined to be rate =
k[A]²[B]. What is the overall order of the reaction?
A) 1
B) 2
C) 3
D) 4
Answer: C
Rationale for A: Order 1 would require exponents summing to 1 (e.g., [A]¹
or [B]¹).
Rationale for B: Order 2 would require exponents summing to 2 (e.g., [A]²
or [A][B]).
Rationale for C: Overall order = sum of exponents = 2 + 1 = 3.
Rationale for D: Order 4 would require exponents summing to 4, which is
not the case here.
4. Which statement about catalysts is TRUE?
,A) Catalysts are consumed in the reaction
B) Catalysts increase the equilibrium constant
C) Catalysts lower the activation energy for both forward and reverse
reactions
D) Catalysts shift equilibrium toward products
Answer: C
Rationale for A: Catalysts are regenerated at the end of the reaction; they
are not consumed.
Rationale for B: Equilibrium constant depends only on thermodynamics
(ΔG°); catalysts affect kinetics only.
Rationale for C: Catalysts provide an alternative pathway with lower Ea for
both directions, speeding up attainment of equilibrium.
Rationale for D: Catalysts do not change equilibrium position; they only
speed up how fast equilibrium is reached.
5. At equilibrium, which of the following is TRUE?
A) The forward and reverse reactions have stopped
B) Concentrations of reactants and products are equal
C) The rate of the forward reaction equals the rate of the reverse reaction
D) The equilibrium constant K equals 1
Answer: C
Rationale for A: Reactions continue at the molecular level; equilibrium is
dynamic, not static.
Rationale for B: Concentrations are constant but not necessarily equal;
ratio is fixed by K.
Rationale for C: This is the definition of dynamic equilibrium: rates are
equal, so no net change.
Rationale for D: K = 1 only when ΔG° = 0; most reactions have K ≠ 1 at
equilibrium.
, 6. For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = -92 kJ. Which change
will shift equilibrium to the RIGHT?
A) Increasing temperature
B) Decreasing pressure
C) Adding a catalyst
D) Removing NH₃ as it forms
Answer: D
Rationale for A: Reaction is exothermic; increasing temperature favors
endothermic (reverse) direction (Le Châtelier).
Rationale for B: Decreasing pressure favors side with more moles of gas (4
vs. 2), shifting equilibrium LEFT.
Rationale for C: Catalysts speed up both directions equally; no shift in
equilibrium position.
Rationale for D: Removing product reduces Q, making Q < K, so reaction
proceeds forward to restore equilibrium.
7. The equilibrium constant expression for 2SO₂(g) + O₂(g) ⇌ 2SO₃(g) is:
A) K = [SO₃]/[SO₂][O₂]
B) K = [SO₃]²/[SO₂]²[O₂]
C) K = [SO₂]²[O₂]/[SO₃]²
D) K = [SO₃]²[O₂]/[SO₂]²
Answer: B
Rationale for A: Missing exponents from stoichiometric coefficients;
incorrect form.
Rationale for B: Correct: products over reactants, each raised to their
coefficient.
Rationale for C: This is the expression for the reverse reaction (1/K).
Rationale for D: Incorrect placement of [O₂]; it should be in the
denominator.
