A-LevelChemistryElectrochemistryMay/June 2023Paper 1 Q111 Mark
LiAlH₄ contains AlH₄⁻ ions in which aluminium has an oxidation state of +3. LiAlH₄ reacts with water, as shown. LiAlH₄ + 4H₂O → 4H₂ + LiOH + Al(OH)₃ In this reaction, each of the four water molecules produces one hydroxide ion. It does this by losing one H⁺ ion, which reacts with the LiAlH₄. Which changes in oxidation number occur in this reaction?
AAl increases by 1 and H decreases by 1.
BH decreases by 2 and also increases by 1.
CH increases by 1 and also decreases by 1.
DO decreases by 1 and H increases by 1.
✓ Correct Answer
The correct answer is C. This question tests the candidate's understanding of electrochemistry within the Chemistrysyllabus. The examiner's mark scheme requires...
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🔒
Unlock the Examiner's Answer
Sign up for free to reveal the correct answer, the official mark scheme breakdown, and the examiner trap analysis for this question.
Sign Up Free to Unlock →Join thousands of Cambridge students already using Oracle Prep