Gibbs Free Energy / Spontaneity Calculator

Inspectable records

Ledger state

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

Area

Chemistry & Materials

Tranche

tranche-4

Evidence ID

t4-243

Ledger rows

1

No ledger note is attached.

Review findings

The listed formulas are standard, but the specification is ambiguous about standard versus nonstandard quantities, omits the crossover formula and the required temperature for the K-to-ΔG° path, and does not define how the spontaneity verdict handles ΔG=0 or invalid crossover temperatures.

Formula and scope findings

• ΔG=ΔH−TΔS is correct when ΔH and ΔS refer to the same reaction and consistent thermodynamic state; the spec does not distinguish ΔG from ΔG° or state whether the inputs are standard quantities.
• ΔG°=−RT ln K is correct only for a dimensionless equilibrium constant K and a specified absolute temperature T; the stated 'K to back out ΔG°' input path does not explicitly require T.
• The claimed crossover temperature requires the additional formula T_eq=ΔH/ΔS and is valid only when ΔS is nonzero; a positive physical crossover temperature is not guaranteed.
• The inverse relation needed to calculate K from ΔG° is not listed explicitly: K=exp(−ΔG°/(RT)).
• A negative ΔG establishes thermodynamic favorability under the specified conditions, not that the reaction will proceed at an observable rate; kinetic limitations are not represented.

Unit assumptions

• T must be in kelvin, not degrees Celsius.
• ΔH and TΔS must use compatible energy units; for example, convert ΔS from J/(mol·K) to kJ/(mol·K) before combining it with ΔH in kJ/mol.
• R must use matching energy units: 8.314462618 J/(mol·K) or 0.008314462618 kJ/(mol·K).
• K is dimensionless and must be defined from a specified standard state; it is not a quantity with units.
• The formulas assume ΔH and ΔS are applicable at the supplied temperature; temperature dependence of heat capacities is ignored unless separately modeled.
• Spontaneity means ΔG<0 is favorable, ΔG=0 is equilibrium, and ΔG>0 is unfavorable for the stated direction under the stated conditions.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

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.

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": {
    "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."
}

Related workflows

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