,CHEM 104 Module 2 | Q&A | 2026/2027 | General Chemistry II |
Portage Learning
1. Identify the compound below as ACID, BASE, or SALT based on its formula:
Cr(OH)₃
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: BASE
Rationale: Cr(OH)₃ is a base because it contains a metal cation (Cr³⁺) bonded
to the hydroxide polyatomic ion (OH⁻). Bases typically have metal + OH
groups. It is not an acid because it does not contain ionizable H⁺, and it is not
a salt because it is not formed from an acid-base neutralization.
2. Identify the compound below as ACID, BASE, or SALT based on its formula:
HAsO₄
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: ACID
Rationale: HAsO₄ is an acid because it contains hydrogen (H⁺) bonded to a
polyatomic group (AsO₄³⁻). Acids typically have the general formula H +
polyatomic group or H + nonmetal. The presence of ionizable H⁺ classifies it
as an acid.
,3. Identify the compound below as ACID, BASE, or SALT based on its formula:
CoCO₃
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: SALT
Rationale: CoCO₃ is a salt because it contains a metal cation (Co²⁺) bonded
to a polyatomic anion (CO₃²⁻). Salts are formed from the neutralization of an
acid and a base and typically consist of a metal + nonmetal or metal +
polyatomic group.
4. In the Brønsted-Lowry acid-base reaction below, identify the stronger acid:
NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: H₃PO₄
Rationale: In a Brønsted-Lowry acid-base reaction, the stronger acid is on the
side with the weaker conjugate base. H₃PO₄ is the stronger acid because its
conjugate base (H₂PO₄⁻) is weaker than NH₄⁺'s conjugate base (NH₃). H₃PO₄
has a lower pKa than NH₄⁺.
, 5. In the Brønsted-Lowry acid-base reaction below, identify the stronger
base: NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: NH₃
Rationale: In a Brønsted-Lowry acid-base reaction, the stronger base is on
the side with the weaker conjugate acid. NH₃ is the stronger base because its
conjugate acid (NH₄⁺) is weaker than H₂PO₄⁻'s conjugate acid (H₃PO₄). NH₃
has a higher Kb than H₂PO₄⁻.
6. In the Brønsted-Lowry acid-base reaction below, identify the weaker acid:
NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: NH₄⁺
Rationale: In a Brønsted-Lowry acid-base reaction, the weaker acid is on the
side with the stronger conjugate base. NH₄⁺ is the weaker acid because its
conjugate base (NH₃) is stronger than H₃PO₄'s conjugate base (H₂PO₄⁻). NH₄⁺
has a higher pKa than H₃PO₄.
Portage Learning
1. Identify the compound below as ACID, BASE, or SALT based on its formula:
Cr(OH)₃
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: BASE
Rationale: Cr(OH)₃ is a base because it contains a metal cation (Cr³⁺) bonded
to the hydroxide polyatomic ion (OH⁻). Bases typically have metal + OH
groups. It is not an acid because it does not contain ionizable H⁺, and it is not
a salt because it is not formed from an acid-base neutralization.
2. Identify the compound below as ACID, BASE, or SALT based on its formula:
HAsO₄
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: ACID
Rationale: HAsO₄ is an acid because it contains hydrogen (H⁺) bonded to a
polyatomic group (AsO₄³⁻). Acids typically have the general formula H +
polyatomic group or H + nonmetal. The presence of ionizable H⁺ classifies it
as an acid.
,3. Identify the compound below as ACID, BASE, or SALT based on its formula:
CoCO₃
A) ACID
B) BASE
C) SALT
D) None of the above
Correct Answer: SALT
Rationale: CoCO₃ is a salt because it contains a metal cation (Co²⁺) bonded
to a polyatomic anion (CO₃²⁻). Salts are formed from the neutralization of an
acid and a base and typically consist of a metal + nonmetal or metal +
polyatomic group.
4. In the Brønsted-Lowry acid-base reaction below, identify the stronger acid:
NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: H₃PO₄
Rationale: In a Brønsted-Lowry acid-base reaction, the stronger acid is on the
side with the weaker conjugate base. H₃PO₄ is the stronger acid because its
conjugate base (H₂PO₄⁻) is weaker than NH₄⁺'s conjugate base (NH₃). H₃PO₄
has a lower pKa than NH₄⁺.
, 5. In the Brønsted-Lowry acid-base reaction below, identify the stronger
base: NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: NH₃
Rationale: In a Brønsted-Lowry acid-base reaction, the stronger base is on
the side with the weaker conjugate acid. NH₃ is the stronger base because its
conjugate acid (NH₄⁺) is weaker than H₂PO₄⁻'s conjugate acid (H₃PO₄). NH₃
has a higher Kb than H₂PO₄⁻.
6. In the Brønsted-Lowry acid-base reaction below, identify the weaker acid:
NH₄⁺ + H₂PO₄⁻ ⇌ NH₃ + H₃PO₄
A) NH₄⁺
B) H₂PO₄⁻
C) NH₃
D) H₃PO₄
Correct Answer: NH₄⁺
Rationale: In a Brønsted-Lowry acid-base reaction, the weaker acid is on the
side with the stronger conjugate base. NH₄⁺ is the weaker acid because its
conjugate base (NH₃) is stronger than H₃PO₄'s conjugate base (H₂PO₄⁻). NH₄⁺
has a higher pKa than H₃PO₄.
