Topic 9 Redox

The following occurs when metal X is added to Y sulfate solution and Z sulfate solution. (X, Y and Z represent metal elements but not their symbols.)

X (s) + YSO₄ (aq) → XSO₄ (aq) + Y (s)

X (s) + ZSO₄ (aq): no reaction

What is the order of increasing reactivity?

• X < Y < Z

• Y < X < Z

• Z < Y < X

• Z < X < Y

Which is the species oxidized and the oxidizing agent in the reaction?

MnO₂ (s) + 4HCl (aq) → MnCl₂ (aq) + Cl₂ (g) + 2H₂O (l)

• A

• B

• C

• D

Which species contains nitrogen with the highest oxidation state?

• NO₃⁻

• NO₂⁻

• NO₂

• N₂O

Which compound contains sulfur with an oxidation state of +6?

• SO₂

• H₂S

• H₂SO₃

• H₂SO₄

Which is correct for the reaction?

P₄ (s) + 3H₂O (l) + 3OH⁻ (aq) → PH₃ (g) + 3H₂PO₂⁻ (aq)

• A

• B

• C

• D

Which represents a reduction?

• SO₃ to SO₄²⁻

• Mn₂O₃ to MnO₂

• H₂O₂ to OH⁻

• CrO₄²⁻ to Cr₂O₇²⁻

Which equation shows oxygen undergoing reduction?

• 2F₂ + O₂ → 2F₂O

• Na₂O + H₂O → 2NaOH

• H₂O₂ + 2HI → 2H₂O + I₂

• 2CrO₄²⁻ + 2H⁺ ⇌ Cr₂O₇²⁻ + H₂O

Which coefficients correctly balance this redox equation?

aFe²⁺(aq) + MnO₄⁻(aq) + bH⁺(aq) →

cFe³⁺(aq) + Mn²⁺(aq) + dH₂O(l)

• A

• B

• C

• D

Which element has the same oxidation number in both species?

• C in C₂H₄ and CO₂

• H in H₂O and NaH

• S in SO₄²⁻and SO₃

• O in H₂O₂ and H₂O

Which can describe oxidation?

• Loss of hydrogen

• Decrease in oxidation number

• Gain of electrons

• Loss of oxygen