Source: https://guthlabs.ai/docs/instruments/standard-entropy-of-reaction-calculator/

instrument / verified-clean

# Standard Entropy of Reaction Calculator

The current ledger marks this instrument verified clean within the source-bound verification corpus.

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

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/standard-entropy-of-reaction-calculator/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/standard-entropy-of-reaction-calculator/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/standard-entropy-of-reaction-calculator/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/standard-entropy-of-reaction-calculator/qualification/>)

## Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

**Area**: Chemistry & Materials

**Tranche**: tranche-4

**Evidence ID**: t4-254

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The summation formula is correct: ΔS°rxn = ΣνiS°i(products) − ΣνiS°i(reactants). Verdict is NEEDS_REVIEW because the specification does not define the temperature, standard-state pressure, or required phase/state metadata. The claim should not imply a uniquely determined value until those conditions are explicit. The declared data source is also not implemented because already_built is false.

### Formula and scope findings

No additional record

### Unit assumptions

- S° values must all use the same temperature, normally 298.15 K unless another temperature is explicitly selected.

- All S° values must be standard molar entropies in the same units; the reported output is J·mol⁻¹·K⁻¹ per mole of reaction as written.

- Stoichiometric coefficients are dimensionless, and fractional coefficients are permitted for a balanced equation.

- Standard states and phases must be specified consistently, typically 1 bar with explicit phases such as (s), (l), (g), or (aq).

- If input entropies are supplied in kJ·mol⁻¹·K⁻¹, they must be converted to J·mol⁻¹·K⁻¹ before reporting the output.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The extreme-magnitude vector produces Infinity in IEEE-754 JavaScript arithmetic because the product entropy sum overflows; the calculator should reject non-finite inputs or outputs. The specification also contains no genuine multi-regime formula branch, so the branch test is necessarily a zero-crossing probe.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "balanced_equation": "CH4(g) + 2 O2(g) -> CO2(g) + 2 H2O(l)",
    "S_standard": {
      "CH4(g)": 186.3,
      "O2(g)": 205,
      "CO2(g)": 213.7,
      "H2O(l)": 69.9
    },
    "S_unit": "J mol^-1 K^-1",
    "temperature_K": 298.15
  },
  "expected_outputs": {
    "delta_S_rxn": -242.8,
    "unit": "J mol^-1 K^-1"
  },
  "working": "Products = (1 × 213.7) + (2 × 69.9) = 213.7 + 139.8 = 353.5 J mol^-1 K^-1. Reactants = (1 × 186.3) + (2 × 205.0) = 186.3 + 410.0 = 596.3 J mol^-1 K^-1. ΔS°rxn = 353.5 − 596.3 = −242.8 J mol^-1 K^-1."
}
````

## Related workflows

[Reaction Energetics BenchΔS](<https://guthlabs.ai/docs/instrument-workflows/reaction-energetics/>)

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_CLEAN`

- `evidence-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`