平衡常数计算器 — 公式

Bond Energy Estimation of ΔH

Formula

ΔH ≈ Σ(bonds broken) − Σ(bonds formed)

Where:

  • Bonds broken = energy required to break all bonds in reactants (positive, endothermic)
  • Bonds formed = energy released forming all bonds in products (positive values)

    • Breaking bonds requires energy; forming bonds releases energy. If more energy is released than absorbed, ΔH is negative (exothermic).

    计算示例

    Combustion of CH₄: bonds broken = 4(C-H) + 2(O=O) = 4(413) + 2(498) = 2648 kJ; bonds formed = 2(C=O) + 4(O-H) = 2(805) + 4(464) = 3466 kJ.

    1. ΔH = Σ(bonds broken) - Σ(bonds formed)
    2. ΔH = 2648 - 3466
    3. ΔH = -818 kJ/mol (exothermic)