Enthalpy change for a reaction is independent of the pathway taken: ΔH_total = Σ ΔH_steps. A direct consequence of H being a state function.
Hess's law
Related concepts
- Enthalpy (H)
- Standard enthalpy of formation (Δ_f H°)
- State function
- Van't Hoff equation: ln(K₂/K₁) = −ΔH/R · (1/T₂ − 1/T₁)
- Van't Hoff toy: ΔH=-R, T₁=1, T₂=1/2 ⇒ ln(K₂/K₁) = 1, K₂/K₁ = e
- Born-Haber cycle: Hess's law applied to ionic-solid formation enthalpies
- Born-Haber NaCl: U_lattice = -787 kJ/mol (ΔH_f = -410 closure)