This common misconceptions covers Common Misconceptions within Electrolysis of Aqueous Solutions for GCSE Chemistry. Revise Electrolysis of Aqueous Solutions in Electrolysis for GCSE Chemistry with 21 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 8 of 13 in this topic. Use this common misconceptions to connect the idea to the wider topic before moving on to questions and flashcards.
⚠️ Common Misconceptions
Misconception 1: "Only the dissolved compound's ions are present in solution"
This is one of the most common errors. Water itself partially ionises: H₂O ⇌ H⁺ + OH⁻. So ANY aqueous solution always contains H⁺ and OH⁻ ions in addition to those from the dissolved salt. This is why the products of aqueous electrolysis can differ from molten electrolysis — hydrogen or oxygen may form instead of the metal or non-metal from the original compound.
Misconception 2: "The more concentrated the solution, the less likely the halogen forms"
The opposite is true. In a dilute halide solution, the OH⁻ concentration is relatively higher, so oxygen may form preferentially at the anode. In a CONCENTRATED halide solution (like brine), Cl⁻ ions greatly outnumber OH⁻ ions, so chlorine is produced. Concentration matters for the anode product when a halide is present.
Misconception 3: "Sodium metal forms at the cathode when brine is electrolysed"
Sodium does NOT form — hydrogen gas forms instead. Because sodium is above hydrogen in the reactivity series, H⁺ ions are more easily reduced and are preferentially discharged. To obtain sodium metal directly, you would need to electrolyse MOLTEN sodium chloride (no water present), as in the Downs process.
Practice questions for Electrolysis of Aqueous Solutions
When sodium chloride (NaCl) is dissolved in water, which four types of ion are present in the solution?
Describe the three products formed when concentrated brine is electrolysed, and state where each is produced.