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Thermochemistry measures heat involved in reactions: ΔH (enthalpy change), ΔS (entropy change), ΔG (Gibbs free energy).

Trin-for-trin guide

  1. 1Input reaction and temperature
  2. 2Calculate ΔH from bond energies or Hess's law
  3. 3Determine spontaneity: ΔG = ΔH - TΔS

Løste eksempler

Input
Combustion: exothermic (ΔH < 0), entropy increases (ΔS > 0)
Resultat
Spontaneous at all temperatures (ΔG < 0)

Almindelige fejl at undgå

  • Assuming exothermic always spontaneous
  • Not accounting for temperature dependence

Ofte stillede spørgsmål

When is reaction spontaneous?

ΔG < 0; depends on temperature through ΔH - TΔS balance.

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