A-LevelChemistryChemical energeticsOct/Nov 2021Paper 4 Q312 Marks
Some data relating to calcium and oxygen are listed. Select relevant data from this list for your answers to parts (c), (d) and (e). [Table of processes and values/kJmol⁻¹: first ionisation energy of oxygen +1310, second ionisation energy of oxygen +3390, first electron affinity of oxygen -142, second electron affinity of oxygen +844, enthalpy change for ½O₂(g) + 2e⁻ → O²⁻(g) +951, enthalpy change for Ca(s) → Ca²⁺(g) + 2e⁻ +1933, lattice energy of CaO(s) -3517]
📋 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...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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