G10 Q4 Chem Review [2025/04/08]

Calculate the pH of a buffer made by mixing

0.1 M NH₃ and 0.1 M NH₄Cl.

K_b(NH₃) = 1.8×10⁻⁵

Report to 2 decimal palces.

Mathematical Equivalence

ON

Consider a buffer solution initially with 0.2 M CH₃COOH and 0.1 M CH₃COONa.

Find the pH when 0.01 M HCl is added to

the said solution.

K_a of acetic acid = 1.74 x 10^-5

Respond to 2 decimal places.

Mathematical Equivalence

ON

Choose the compound where chromium exhibits the lowest oxidation number.

• CrCl₃

• Cr(H₂O)₆³⁺

• CrO

• CrO₄^2-

• Cr₂O₇²

Define a as the oxidation number of magnesium in permanganate.

Define b as the oxidation number of oxygen in manganese (II) oxide.

What is a + b.

Mathematical Equivalence

ON

Identify the reducing agent in the following reaction:

Cl₂​ + 2 Br⁻ → 2 Cl⁻ + Br₂​

• chlorine

• bromide ion

• chloride ion

• bromine

Identify the oxidizing agent in the following reaction:

Cl₂​ + 2 Br⁻ → 2 Cl⁻ + Br₂​

• chlorine

• bromide ion

• chloride ion

• bromine

What is the coefficient of hydronium ions in the balanced equation of:

Cr₂O₇^2- (aq) + HNO₂ (aq) → Cr³⁺ (aq) + NO₃⁻ (aq)

Provide the least possible integer coefficient.

Mathematical Equivalence

ON

Answer explanation

3HNO2(aq)+5H+(aq)+Cr2O2−7(aq)→3NO−3(aq)+2Cr3+(aq)+4H2O(l)3HNO2(aq)+5H+(aq)+Cr2O72−(aq)→3NO3−(aq)+2Cr3+(aq)+4H2O(l)

Which of the following cell notations represent the galvanic cell with the following half-reactions:

Cu²⁺ + 2e⁻ → Cu (E° = +0.34 V)

• Zn²⁺ + 2e⁻ → Zn (E° = –0.76 V)

• Cu(s) ∣ Cu²⁺(aq) ∣∣ Zn²⁺(aq) ∣ Zn(s)

• Cu²⁺(aq) ∣ Cu(s) ∣∣ Zn(s) ∣ Zn²⁺(aq)

• Zn(s) ∣ Zn²⁺(aq) ∣∣ Cu²⁺(aq) ∣ Cu(s)

• Zn²⁺(aq) ∣ Zn(s) ∣∣ Cu(s) ∣ Cu²⁺(aq)

What species acts as the cathode in the following cell:

Zn(s) ∣ Zn²⁺(aq) ∣∣ Cu²⁺(aq) ∣ Cu(s)

• zinc

• zinc ion

• copper ion

• copper

Calculate the standard cell potential of the following galvanic cell:

Zn(s) ∣ Zn²⁺(aq) ∣∣ Cu²⁺(aq) ∣ Cu(s)

Cu²⁺ + 2e⁻ → Cu (E° = +0.34 V)

• Zn²⁺ + 2e⁻ → Zn (E° = –0.76 V)

Use the correct number of significant figures.

Mathematical Equivalence

ON