Source: https://guthlabs.ai/docs/instruments/bond-enthalpy-reaction-estimator/mechanism/

instrument mechanism / verified-clean

# Bond Enthalpy Reaction Estimator mechanism

The inspectable method record for Bond Enthalpy Reaction Estimator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The arithmetic engine and stated approximation formula are acceptable. Review is required because the lookup table values, bond-type conventions, phase assumptions, and exact output unit are not specified sufficiently for deterministic production results. The honest-label warning is appropriate but should also state that average bond energies usually approximate gas-phase reaction enthalpies rather than exact ΔH°rxn values.

- The formula ΔH≈Σ(bonds broken)−Σ(bonds formed) is the standard average-bond-enthalpy estimate when all bond energies are positive dissociation energies and bond counts are stoichiometrically correct.

- The specification does not provide the actual bond-energy lookup values or define the table version, so results are not reproducible from the specification alone.

- The output is labeled ΔH°rxn, but average bond dissociation energies generally estimate gas-phase reaction enthalpies and do not directly provide exact standard enthalpies, especially when condensed phases are involved.

- The input contract should explicitly require nonnegative integer bond counts, valid bond-type keys, and complete accounting of every bond broken and formed.

## Units and conventions

- All listed bond energies are positive average bond dissociation energies in kJ/mol of bonds.

- The reported result is kJ/mol of reaction as written, not kJ/mol of individual bonds.

- The reaction is treated as a gas-phase bond-counting estimate unless phase handling is explicitly added.

- Bond energies are assumed to come from one consistent lookup table and bond notation, such as C-H, C-C, C=C, O=O, O-H, H-H, Cl-Cl, and H-Cl.

- No conversion between kJ/mol and other energy units is performed unless explicitly implemented.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "reaction": "H2(g) + Cl2(g) -> 2 HCl(g)",
    "bonds_broken": [
      {
        "bond": "H-H",
        "count": 1,
        "energy_kJ_per_mol": 436
      },
      {
        "bond": "Cl-Cl",
        "count": 1,
        "energy_kJ_per_mol": 243
      }
    ],
    "bonds_formed": [
      {
        "bond": "H-Cl",
        "count": 2,
        "energy_kJ_per_mol": 431
      }
    ]
  },
  "expected_outputs": {
    "estimated_delta_H_kJ_per_mol_reaction": -183
  },
  "working": "Broken-bond sum = (1 × 436) + (1 × 243) = 436 + 243 = 679 kJ/mol. Formed-bond sum = 2 × 431 = 862 kJ/mol. ΔH ≈ 679 − 862 = −183 kJ/mol reaction."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The extreme finite-looking count produces Infinity for both bond-energy sums and then Infinity − Infinity = NaN; without finite and physical-input validation, the estimator returns an undefined result. The specification also has no actual formula branch, despite requiring branch-switch testing.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/bond-enthalpy-reaction-estimator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/bond-enthalpy-reaction-estimator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/bond-enthalpy-reaction-estimator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`