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Why enthalpy is not enough

Why enthalpy is not enough

Exothermic reactions often seem favourable because they move to a lower enthalpy, so AS chemistry used ΔH\Delta HΔH as a guide. But enthalpy alone cannot explain spontaneous endothermic changes, such as ice melting above 273 K273 \, \text{K}273K.

Gibbs free-energy change, ΔG, and entropy change, ΔS (A-level only) Lesson

  1. A Level
  2. /Chemistry
  3. /Gibbs free-energy change, ΔG, and entropy change, ΔS (A-level only)

Step-by-step lessons on AQA A Level Chemistry Gibbs free-energy change, $\Delta G$ , and entropy change, $\Delta S$ (A-level only). Each one builds up to exam-style questions. Build confidence with atomic structure, bonding and moles calculations early on, since these underpin the more demanding organic mechanisms, equilibrium and practical-analysis topics that dominate Year 2.

Lessons