Grade 12 Physical Sciences · Chemical Change

Describe an electrolytic cell

Describe how an electrolytic cell uses electricity to cause a reaction, including what forms at each electrode (electroplating a spoon with silver).

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Electrochemistry Gr 12 : Electrolytic cellsKevinmathscience

Electrolytic Cell Electrochemistry: How electrolysis works | Grade 12 ChemistryMiss Martins Maths and Science

Electrochemistry Gr 12 : ElectroplatingKevinmathscience

Electrolytic Cell Electrorefining: Electrochemistry Grade 12 ChemistryMiss Martins Maths and Science

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Question 1.10 · May/June 2025 · Paper 2 · National (DBE) · 2 marks

1.10 Impure copper is refined in an electrolytic cell. Which ONE of the following combinations CORRECTLY identifies the anode and the electrolyte for this cell?(2)

A Anode: Pure copper; Electrolyte: $Cu(NO_{3})_{2}$ (aq)
B Anode: Pure copper; Electrolyte: $AgNO_{3}$ (aq)
C Anode: Impure copper; Electrolyte: $Cu(NO_{3})_{2}$ (aq)
D Anode: Impure copper; Electrolyte: $AgNO_{3}$ (aq)

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3. Question 1.10 · November 2024 · Paper 2 · National (DBE) · 2 marks
Various options are provided as possible answers to the following questions. Each question has only ONE correct answer. Choose the answer and write only the letter (A–D) next to the question numbers (1.1 to 1.10) in the ANSWER BOOK, e.g. 1.11 E.
1.10 An electrolytic cell is set up to electroplate an iron rod with nickel, as shown in the diagram below.

Consider the following statements:

(i) The iron rod is the negative electrode.
(ii) The metal ions in the solution undergo reduction.
(iii) The anode is pure nickel.

Which of the above statements are TRUE?(2)
1. A (i) and (ii) only
2. B (i) and (iii) only
3. C (ii) and (iii) only
4. D (i), (ii) and (iii)
Show the memo (1 tick)Memo
1. ✓
  Correct option(i) The object to be plated (iron rod) is the cathode, which in an electrolytic cell is the negative electrode. TRUE.
  (ii) $Ni^{2 +}$ ions in the solution gain electrons at the cathode and are deposited as Ni: reduction. TRUE.
  (iii) The anode is made of the plating metal, pure nickel, which is oxidised to replace the $Ni^{2 +}$ ions. TRUE.
  
  Answer: D
  2 marks · Describe an electrolytic cell
4. Question 1.9 · May/June 2024 · Paper 2 · National (DBE) · 2 marks
1.9 Copper is purified by electrolysis, as shown in the diagram below.

Which ONE of the following combinations is CORRECT for the changes occurring at the anode, cathode and in the electrolyte when the cell is in operation?(2)
1. A Mass of the anode: Increases; Mass of the cathode: Decreases; Colour of the electrolyte: No change
2. B Mass of the anode: Decreases; Mass of the cathode: Increases; Colour of the electrolyte: No change
3. C Mass of the anode: Increases; Mass of the cathode: Decreases; Colour of the electrolyte: Becomes darker
4. D Mass of the anode: Decreases; Mass of the cathode: Increases; Colour of the electrolyte: Becomes lighter
Show the memo (1 tick)Memo
1. ✓
  Choose the correct optionThe impure copper anode is oxidised ( $Cu \to Cu^{2 +} + 2 e^{-}$ ), so it loses mass. At the pure copper cathode $Cu^{2 +}$ ions are reduced to Cu, so it gains mass. Copper ions enter the solution at the same rate as they leave it, so $[Cu^{2 +}]$ and the blue colour stay the same.
  
  Answer: B
  2 marks · Describe an electrolytic cell
5. Question 9.2.3 · November 2024 · Paper 2 · National (DBE) · 2 marks
9.2 The simplified diagram below represents an electrolytic cell. The electrodes are made of carbon.

Answer the questions that follow.
9.2.3 Write down the NAMES or FORMULAE of the products formed at electrode Q.(2)
Show the memo (2 ticks)Memo
1. ✓
  Hydroxide ionsHydroxide ions / $OH^{-}$ / sodium hydroxide / NaOH
  1 mark · Describe an electrolytic cell
2. ✓
  HydrogenHydrogen / $H_{2}$
  1 mark · Describe an electrolytic cell
6. Question 1.10 · May/June 2023 · Paper 2 · National (DBE) · 2 marks
1.10 A concentrated solution of sodium chloride, NaCℓ(aq), undergoes electrolysis.

Which ONE of the combinations correctly shows the products formed at each electrode?(2)
1. A Cathode: Na; Anode: Cℓ $_{2}$
2. B Cathode: $H_{2}$ ; Anode: $OH^{-}$
3. C Cathode: Cℓ $_{2}$ ; Anode: $H_{2}$ and $OH^{-}$
4. D Cathode: $H_{2}$ and $OH^{-}$ ; Anode: Cℓ $_{2}$
Show the memo (1 tick)Memo
1. ✓
  Products of the electrolysis of concentrated NaCℓ(aq)Cathode (reduction): water is a stronger oxidising agent than $Na^{+}$ , so $2 H_{2} O + 2 e^{-} \to H_{2} + 2 OH^{-}$ .
  Anode (oxidation): in a CONCENTRATED chloride solution, $2 Cl^{-} \to Cl_{2} + 2 e^{-}$ .
  
  Answer: D
  2 marks · Describe an electrolytic cell

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