Free Electrochemistry questions for AS Level Chemistry (9701), part of Physical chemistry. Each question has the answer and the marking points an examiner would look for.
Generate a full Electrochemistry worksheet →All Physical chemistry questionsWhich term is described by this statement?
“A reaction in which the same element is both oxidised and reduced.”
Answer: B
Chlorine reacts with cold dilute aqueous sodium hydroxide.
What are the oxidation numbers of chlorine in the two chlorine-containing products?
| in NaCl | in NaClO | |
|---|---|---|
| A | −1 | +5 |
| B | −1 | +1 |
| C | +1 | −1 |
| D | 0 | +1 |
Answer: B
What is the oxidation number of S in H2SO3?
Answer: C
Oxidation numbers are used to identify redox reactions.
Deduce the oxidation number of manganese in MnO₄⁻ and of chromium in Cr₂O₇²⁻.
Construct the ionic equation for the reaction of MnO₄⁻ with Fe²⁺ in acid.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | +7; +6 Mn +7 B1 Cr +6 B1 | 2 |
| (b) | MnO₄⁻ + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 4H₂O + 5Fe³⁺ correct species M1 balanced A1 | 2 |
An iron tablet was dissolved in dilute sulfuric acid and the solution made up to 100 cm3. 25.0 cm3 portions needed 22.40 cm3 of 0.00200 mol dm−3 potassium manganate(VII) to reach the end-point. MnO₄⁻ + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O
State the change in oxidation number of manganese.
Write the two half-equations for this reaction.
Calculate the mass of iron in the tablet.
State the colour change at the end-point.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | +7 to +2 +7 to +2 B1 | 1 |
| (b) | MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O; Fe²⁺ → Fe³⁺ + e⁻ MnO₄⁻ + 8H⁺ + 5e⁻ → Mn²⁺ + 4H₂O B1 Fe²⁺ → Fe³⁺ + e⁻ B1 | 2 |
| (c) | 0.0500 g n(MnO₄⁻) = 4.48 × 10−5 mol C1 n(Fe²⁺) in 100 cm3 = 8.96 × 10−4 mol C1 mass = 0.0500 g A1 | 3 |
| (d) | colourless to pale pink colourless to (permanent) pale pink B1 | 1 |
Electrolysis of aqueous copper(II) sulfate uses copper electrodes.
Write the half-equations at the anode and cathode.
A current of 0.50 A is passed for 30 minutes. Calculate the mass of copper deposited. (F = 96 500 C mol−1)
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | Cu → Cu²⁺ + 2e⁻; Cu²⁺ + 2e⁻ → Cu anode: Cu → Cu²⁺ + 2e⁻ B1 cathode: Cu²⁺ + 2e⁻ → Cu B1 | 2 |
| (b) | 0.296 g Q = It = 900 C C1 mol Cu = 900/(2 × 96 500) C1 0.296 g A1 | 3 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in