Year 12 Chemistry Chapter 4

Which one of the following redox equations has not been balanced correctly?

• Ni(s) is oxidised and Cu²⁺(aq) is the oxidising agent

• Ni(s) is reduced and Cu²⁺(aq) is the oxidising agent

• Ni(s) is oxidised and Cu²⁺(aq) is the reducing agent

• Ni(s) is reduced and Cu²⁺(aq) is the reducing agent

Which one of the following is not a redox reaction?

Which of the following directly identifies the oxidant and reductant in the corrosion process shown in the given equation?

2𝐹𝑒(𝑠)+ 𝑂₂(𝑔)+𝐻₂𝑂 (𝑙)→ 2𝐹𝑒²⁺(𝑎𝑞)+4𝑂𝐻⁻(𝑎𝑞)

• oxidant: O₂

  reductant: H₂O

• oxidant: O₂

  reductant: Fe

• oxidant: H₂O

  reductant: H₂O

• oxidant: H₂O

  reductant: Fe

Consider the following particles:

𝑀𝑛𝑂₄⁻ 𝐾₂𝐶𝑟₂𝑂₇ 𝐶𝐻₄ 𝑁³⁻

The oxidation numbers of the respective elements are:

• Mn Cr C N

  +8 +6 -4 -3

• Mn Cr C N

  +8 +12 -4 -3

• Mn Cr C N

  +7 +6 -4 -3

• Mn Cr C N

  +7 +6 +4 -3

Magnesium reacts with nickel (II) ions according to the following equation:

𝑁𝑖²⁺(𝑎𝑞)+𝑀𝑔(𝑠)→ 𝑁𝑖(𝑠)+ 𝑀𝑔²⁺(𝑎𝑞)

Which one of the following is the correct set of conjugate redox pairs for this reaction?

• 𝑀𝑔²⁺(𝑎𝑞)/𝑀𝑔(𝑠) 𝑎𝑛𝑑 𝑁𝑖²⁺(𝑎𝑞)/𝑁𝑖(𝑠)

• 𝑁𝑖(𝑠)/ 𝑀𝑔²⁺(𝑎𝑞) and 𝑁𝑖²⁺(𝑎𝑞)/𝑀𝑔(𝑠)

• 𝑀𝑔(𝑠)/𝑁𝑖(𝑠) and 𝑁𝑖²⁺(𝑎𝑞)/𝑀𝑔²⁺(𝑎𝑞)

• 𝑀𝑔(𝑠)/𝑁𝑖²⁺(𝑎𝑞)and 𝑁𝑖(𝑠)/𝑀𝑔²⁺(𝑎𝑞)

Which one of the following is not a redox reaction?

• 2𝐹𝑒³⁺(𝑎𝑞)+𝑆𝑛²⁺(𝑎𝑞) → 2𝐹𝑒²⁺(𝑎𝑞)+𝑆𝑛⁴⁺(𝑎𝑞)

• 𝑀𝑔(𝑠)+𝑂₂ (𝑔) → 2𝑀𝑔𝑂(𝑠)

• 2𝑁𝑎(𝑠)+2𝐻₂𝑂(𝑙) → 𝐻₂(𝑔)+2𝑁𝑎𝑂𝐻(𝑎𝑞)

• 𝐴𝑔⁺(𝑎𝑞)+𝐶𝑙⁻(𝑎𝑞) → 𝐴𝑔𝐶𝑙(𝑠)

The equation for the redox reaction betweeen manganese dioxide and hydrochloric acid is:

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

The reduction half equation occurring is:

• 2𝐶𝑙⁻(𝑎𝑞) → 𝐶𝑙₂(𝑔) + 2𝑒⁻

• 4𝐻⁺(𝑎𝑞) + 4𝑒⁻ → 2𝐻₂(𝑔)

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

• 𝑀𝑛𝑂₂(𝑠) + 4𝐻⁺ (𝑎𝑞) + 2𝑒⁻ → 𝑀𝑛²⁺(𝑎𝑞) + 2𝐻₂𝑂(𝑙)

Ethanol can be oxidised in acidic conditions to ethanoic acid. The half-equation for this reaction is:

• 𝐶₂𝐻₅𝑂(𝑎𝑞) + 𝐻₂𝑂(𝑙) → 𝐶₂𝐻₄𝑂₂(𝑎𝑞) + 3𝐻⁺(𝑎𝑞) + 4𝑒⁻

• 𝐶₂𝐻₆𝑂(𝑎𝑞) + 𝐻₂𝑂(𝑙) + 4𝑒⁻ → 𝐶₂𝐻₄𝑂₂(𝑎𝑞) + 4𝐻⁺(𝑎𝑞)

• 𝐶₂𝐻₆𝑂(𝑎𝑞) + 𝐻₂𝑂(𝑙) → 𝐶₂𝐻₄𝑂₂(𝑎𝑞) + 4𝐻⁺(𝑎𝑞) + 4𝑒⁻

• 𝐶₂𝐻₆𝑂(𝑎𝑞) + OH^-(aq) → 𝐶₂𝐻₄𝑂₂(𝑎𝑞) + H₂(𝑎𝑞) + 2𝑒⁻

• Na(s) is the oxidising agent, Ag⁺(aq) is the reducing agent, sodium metal is reduced

• Na(s) is the reducing agent, Ag⁺(aq) is the oxidising agent, sodium metal is reduced.

• Na⁺(aq) is the oxidising agent, Ag(s) is the reducing agent, sodium metal is oxidised

• Na(s) is the reducing agent, Ag⁺(aq) is the oxidising agent, sodium metal is oxidised