CHEM 104 Final Exam - Cumulative Review (Modules 1-7) 2026/2027
UPDATE
1. Which of the following describes a system at chemical equilibrium?
A. The concentrations of reactants and products are equal.
B. The reaction has completely stopped.
C. The forward and reverse reaction rates are equal.
D. The mass of the products exceeds the mass of the reactants.
Answer: C
Rationale: Chemical equilibrium is a dynamic state where the rate of the forward reaction
equals the rate of the reverse reaction, resulting in no net change in concentrations.
2. What is the pH of a solution with a hydrogen ion concentration [H+] of 1.0 x
10^-5 M?
A. 5.0
B. 9.0
C. -5.0
D. 7.0
Answer: A
Rationale: pH is calculated using the formula -log[H+]. For 1.0 x 10^-5, the -log is 5.0.
,3. In the reaction: N2 + 3H2 -> 2NH3, how many moles of NH3 are produced
from 6 moles of H2, assuming N2 is in excess?
A. 2 moles
B. 3 moles
C. 4 moles
D. 6 moles
Answer: C
Rationale: The stoichiometric ratio of H2 to NH3 is 3:2. (6 moles H2) * (2 moles NH
moles H2) = 4 moles NH3.
4. Which functional group is characteristic of an alcohol?
A. -COOH
B. -NH2
C. -OH
D. -CHO
Answer: C
Rationale: The hydroxyl group (-OH) is the defining functional group for alcohols.
5. According to Le Chatelier’s Principle, what happens to the equilibrium
2SO2(g) + O2(g) ⇌ 2SO3(g) if pressure is increased?
A. Shifts to the right (products)
B. Shifts to the left (reactants)
C. No change occurs
D. The equilibrium constant K increases
Answer: A
Rationale: Increasing pressure shifts the equilibrium toward the side with fewer moles of
gas. The right side has 2 moles, while the left has 3.
, 6. What is the oxidation state of sulfur in H2SO4?
A. +2
B. +4
C. -2
D. +6
Answer: D
Rationale: H is +1 (x2 = +2), O is -2 (x4 = -8). To make the molecule neutral (0), S must be
+6.
7. Which of the following is an example of an endothermic process?
A. Water freezing into ice
B. Combustion of methane
C. Neutralization of an acid by a base
D. Ice melting into liquid water
Answer: D
Rationale: Melting requires the absorption of heat from the surroundings to break
intermolecular forces, making it endothermic.
8. Identify the conjugate acid of the base HPO4^2-.
A. PO4^3-
B. OH-
C. H3PO4
D. H2PO4^-
Answer: D
Rationale: A conjugate acid is formed when a base accepts a proton (H+). Adding H+ to
HPO4^2- results in H2PO4^-.
UPDATE
1. Which of the following describes a system at chemical equilibrium?
A. The concentrations of reactants and products are equal.
B. The reaction has completely stopped.
C. The forward and reverse reaction rates are equal.
D. The mass of the products exceeds the mass of the reactants.
Answer: C
Rationale: Chemical equilibrium is a dynamic state where the rate of the forward reaction
equals the rate of the reverse reaction, resulting in no net change in concentrations.
2. What is the pH of a solution with a hydrogen ion concentration [H+] of 1.0 x
10^-5 M?
A. 5.0
B. 9.0
C. -5.0
D. 7.0
Answer: A
Rationale: pH is calculated using the formula -log[H+]. For 1.0 x 10^-5, the -log is 5.0.
,3. In the reaction: N2 + 3H2 -> 2NH3, how many moles of NH3 are produced
from 6 moles of H2, assuming N2 is in excess?
A. 2 moles
B. 3 moles
C. 4 moles
D. 6 moles
Answer: C
Rationale: The stoichiometric ratio of H2 to NH3 is 3:2. (6 moles H2) * (2 moles NH
moles H2) = 4 moles NH3.
4. Which functional group is characteristic of an alcohol?
A. -COOH
B. -NH2
C. -OH
D. -CHO
Answer: C
Rationale: The hydroxyl group (-OH) is the defining functional group for alcohols.
5. According to Le Chatelier’s Principle, what happens to the equilibrium
2SO2(g) + O2(g) ⇌ 2SO3(g) if pressure is increased?
A. Shifts to the right (products)
B. Shifts to the left (reactants)
C. No change occurs
D. The equilibrium constant K increases
Answer: A
Rationale: Increasing pressure shifts the equilibrium toward the side with fewer moles of
gas. The right side has 2 moles, while the left has 3.
, 6. What is the oxidation state of sulfur in H2SO4?
A. +2
B. +4
C. -2
D. +6
Answer: D
Rationale: H is +1 (x2 = +2), O is -2 (x4 = -8). To make the molecule neutral (0), S must be
+6.
7. Which of the following is an example of an endothermic process?
A. Water freezing into ice
B. Combustion of methane
C. Neutralization of an acid by a base
D. Ice melting into liquid water
Answer: D
Rationale: Melting requires the absorption of heat from the surroundings to break
intermolecular forces, making it endothermic.
8. Identify the conjugate acid of the base HPO4^2-.
A. PO4^3-
B. OH-
C. H3PO4
D. H2PO4^-
Answer: D
Rationale: A conjugate acid is formed when a base accepts a proton (H+). Adding H+ to
HPO4^2- results in H2PO4^-.
