Chemistry study notes
Chemical Energetics: Thermochemistry
Read reaction energy, measure heat and use supplied cycles without losing signs or stoichiometric factors.
A-Level 8873, revised syllabus (2026-2027)
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6. Chemical Energetics: Thermochemistry (8873, 2026 revision; examinations 2026 and 2027). Use the outcome map to find the explanation for a particular syllabus requirement.
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6(a) Explain exothermic and endothermic changes.
- Bond breaking/forming, heat transfer and sign of enthalpy.
6(b) Construct and interpret energy profiles.
- Reaction enthalpy, activation energy and link to kinetics.
6(c) Define the specified energy terms.
- (i) Reaction enthalpy, standard conditions, formation, combustion and neutralisation.
- (ii) Bond energy as positive bond breaking.
- (iii) Lattice energy as negative gaseous-ion-to-solid formation.
Name the exact process and amountBreaking needs energy; forming releases it
6(d) Calculate experimental enthalpy changes.
- q = mcDeltaT; heat sign, reacting amount and assumptions.
6(e) Explain lattice-energy magnitude.
- Effects of ionic charge and radius, qualitative only.
6(f) Use supplied Hess cycles and bond energies.
- Supplied simple cycles; formation/combustion/neutralisation scope.
- (i) Indirect determination, including formation from combustion.
- (ii) Average bond energies; cycle construction not required.