How to use the reaction enthalpy from bond energies calculator
Estimate reaction enthalpy from bonds broken and formed. Enter total energy of bonds broken, total energy of bonds formed in the fields above; the reaction enthalpy δh, type are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- Eb — Total energy of bonds broken (kJ/mol)
- Ef — Total energy of bonds formed (kJ/mol)
Worked example
With total energy of bonds broken = 2648 kJ/mol, total energy of bonds formed = 3474 kJ/mol, the calculator gives reaction enthalpy δh ≈ -826 kJ/mol; type ≈ Exothermic.
Frequently asked questions
What is the formula for the reaction enthalpy from bond energies calculation?
Reaction enthalpy ΔH (kJ/mol) = Eb-Ef. Type = [Reaction enthalpy ΔH]<0?"Exothermic":"Endothermic". Here Eb is total energy of bonds broken (kJ/mol), Ef is total energy of bonds formed (kJ/mol).
What inputs do I need for the reaction enthalpy from bond energies calculator?
You need total energy of bonds broken in kJ/mol, total energy of bonds formed in kJ/mol. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.