Gibbs Free Energy / Spontaneity Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-243

Effect

Computation or source lookup only

Input and validation requirements

The crossover-temperature calculation has an explicit division-by-zero failure when ΔS=0 and must return undefined or reject the request. The specification also leaves unit and direction conventions implicit, allowing a 1000-fold entropy-unit error or a reversed spontaneity verdict if conventions are not enforced.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "ΔH": "-100 kJ/mol",
    "ΔS": "-200 J/(mol·K)",
    "T": "298 K"
  },
  "expected_outputs": {
    "ΔG": "-40.4 kJ/mol",
    "spontaneity": "favorable (ΔG<0)",
    "crossover_temperature": "500 K"
  },
  "working": "Convert ΔS: −200 J/(mol·K) ÷ 1000 = −0.200 kJ/(mol·K). Compute TΔS: 298 K × (−0.200 kJ/(mol·K)) = −59.6 kJ/mol. Compute ΔG: −100 kJ/mol − (−59.6 kJ/mol) = −40.4 kJ/mol. Since ΔG<0, the direction is thermodynamically favorable. Set ΔG=0 for crossover: T_eq=ΔH/ΔS=(−100 kJ/mol)/(−0.200 kJ/(mol·K))=500 K."
}

Other records

Sources and evidence

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

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json