Question detail

Chemical changes case 007 redox-boundary. A student explains a redox change. Which option uses the safest chemistry wording? Focus on why aluminium oxide dissolved molten cryolite during extraction in Using electrolysis to extract metals, not on a neighbouring Unit 4.4 reaction idea.

Try the question, check the answer, then read the explanation to understand the curriculum point.

Show answer Topic hub Objective page

At a glance

MCQ

Type

practice

Style

Topic

Electrolysis

Question

A. Chemical changes case 007 redox-boundary: Links oxidation or reduction to the correct electron or oxygen change for why aluminium oxide dissolved molten cryolite during extraction
B. Chemical changes case 007 redox-boundary: Uses reduction and displacement as if they mean the same thing (Using electrolysis to extract metals)
C. Chemical changes case 007 redox-boundary: Calls the reaction redox without naming what changes (why aluminium oxide dissolved molten cryolite during extraction)
D. Chemical changes case 007 redox-boundary: Confuses oxidation state with ionic charge in the answer (Electrolysis)

Answer

Explanation

The correct option is Chemical changes case 007 redox-boundary: Links oxidation or reduction to the correct electron or oxygen change for why aluminium oxide dissolved molten cryolite during extraction. It is correct because it directly supports the approved learning objective to explain why aluminium oxide is dissolved in molten cryolite during extraction in Using electrolysis to extract metals. The other options are incorrect because they blur a Unit 4.4 concept boundary: acid versus alkali versus base, oxidation versus reduction, displacement versus reduction, electrolysis versus electroplating, anode versus cathode, positive versus negative ions, oxidation state versus ionic charge, or strong acid versus concentrated acid.

Common mistake

Aluminium oxide dissolves in molten cryolite because it reacts chemically

Students often think aluminium oxide dissolves in molten cryolite due to a chemical reaction between Al₂O₃ and Na₃AlF₆, forming new compounds.

Aluminium oxide dissolves in molten cryolite simply because cryolite is a molten salt that provides a low‑melting, electrically conductive medium; the Al₂O₃ remains chemically unchanged and is only dispersed in the melt, not reacted with the cryolite.

Related flashcards

Flashcard 1 of 5

Press Space to flip, arrows to move

For Using electrolysis to extract metals, which redox focus answer best supports this Unit 4.4 objective: Explain why aluminium oxide is dissolved in molten cryolite during extraction?