Thermodynamic state function H = U + pV. At constant pressure, ΔH equals the heat of reaction: exothermic (ΔH < 0) or endothermic (ΔH > 0).
Enthalpy (H)
Related concepts
- First law of thermodynamics
- Gibbs free energy (G)
- Hess's law
- Bond dissociation energy
- Standard enthalpy of formation (Δ_f H°)
- Calorimetry
- Calorimetry
- State function
- Hess's law & thermochemical cycles
- Gibbs free energy G = H − TS (spontaneity at fixed T, P)
- Gibbs-Helmholtz: d(G/T)/dT = −H/T²
- d(G/T)/dT simplifies to -H/T²; residual 0 (operator-level identity)