Physical Chemistry

Worked examples (5)

• 1Calculate ΔH for the combustion of methane from bond energies (7 marks, Paper 1)
• 2Drawing and labelling a reaction profile for an endothermic reaction (5 marks, Paper 1)
• 3Calorimetry: measure ΔH of neutralisation (6 marks, Paper 1)
• 4Calorimetry: enthalpy of combustion of ethanol (6 marks, Paper 1)
• 5Bond breaking vs bond making (5 marks, Paper 1)

Model answers (5)

• ✓Model answer — 4CH1/1C-style — exothermic / endothermic definitions
• ✓Model answer — 4CH1/1C-style — reaction profiles
• ✓Model answer — 4CH1/1C-style — bond energy calculation
• ✓Model answer — 4CH1/2C-style — calorimetry experiment
• ✓Model answer — 4CH1/2C-style — bond energy / particle theory

Worked examples (5)

• 1Explain in terms of collision theory why concentration affects rate (5 marks, Paper 1)
• 2Temperature effect on rate: two reasons (6 marks, Paper 1)
• 3Explain how a catalyst works (energy profile diagram) (5 marks, Paper 1)
• 4Investigating the effect of surface area on rate (6 marks, Paper 1)
• 5Calculate rate from a volume-time graph (5 marks, Paper 1)

Model answers (4)

• ✓Model answer — 4CH1/1C-style — collision theory overview
• ✓Model answer — 4CH1/2C-style — catalysts in detail
• ✓Model answer — 4CH1/1C-style — experimental rate-measuring methods
• ✓Model answer — 4CH1/2C-style — concentration vs rate experiment

Worked examples (5)

• 1Explain what is meant by a dynamic equilibrium (5 marks, Paper 2)
• 2Le Chatelier — predict the effect of temperature (5 marks, Paper 2)
• 3Le Chatelier — predict the effect of pressure (5 marks, Paper 2)
• 4Why a catalyst does NOT shift equilibrium (4 marks, Paper 2)
• 5Conditions for the Haber process — full compromise explanation (8 marks, Paper 2)

Model answers (4)

• ✓Model answer — 4CH1/2C-style — dynamic equilibrium
• ✓Model answer — 4CH1/2C-style — Le Chatelier overview
• ✓Model answer — 4CH1/2C-style — Haber compromise
• ✓Model answer — 4CH1/2C-style — Contact process