Q: Table 3 shows products of the electrolysis of two molten ionic compounds. Complete Table 3. Table 3 Molten compound Product at the negative electrode Product at the positive electrode Magnesium bromide Magnesium Potassium chloride Chlorine

During electrolysis of a molten ionic compound:\n- The positive metal ion (cation) is attracted to the negative electrode (cathode), where it gains electrons and forms the metal element.\n- The negative non-metal ion (anion) is attracted to the positive electrode (anode), where it loses electrons and forms the non-metal element.\n1. For Magnesium bromide (MgBr₂), the ions are Mg²⁺ and Br⁻. The positive electrode will attract the negative Br⁻ ions, which form bromine.\n2. For Potassium chloride (KCl), the ions are K⁺ and Cl⁻. The negative electrode will attract the positive K⁺ ions, which form potassium.

Q: What mistakes do candidates make on this AQA GCSE question?

✗ Getting the electrodes mixed up.\n✗ Naming the ion instead of the element (e.g., bromide instead of bromine).

Question 1

Table 3 shows products of the electrolysis of two molten ionic compounds. Complete Table 3.

Table 3
Molten compound	Product at the negative electrode	Product at the positive electrode
Magnesium bromide	Magnesium
Potassium chloride		Chlorine

Accepted Answer

During electrolysis of a molten ionic compound:
- The positive metal ion (cation) is attracted to the negative electrode (cathode), where it gains electrons and forms the metal element.
- The negative non-metal ion (anion) is attracted to the positive electrode (anode), where it loses electrons and forms the non-metal element.
1. For Magnesium bromide (MgBr₂), the ions are Mg²⁺ and Br⁻. The positive electrode will attract the negative Br⁻ ions, which form bromine.
2. For Potassium chloride (KCl), the ions are K⁺ and Cl⁻. The negative electrode will attract the positive K⁺ ions, which form potassium.

Question 2

What mistakes do candidates make on this AQA GCSE question?

Accepted Answer

✗ Getting the electrodes mixed up.
✗ Naming the ion instead of the element (e.g., bromide instead of bromine).

How to approach this question

Full Answer

Common mistakes

Practice the full AQA GCSE Chemistry Foundation Tier Paper 1

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