Combined/Combined-Gas-Law Calculator mechanism

Model scope

The algebraic formula is correct, but the specification needs an explicit variable-selection interface, valid-domain constraints, absolute-temperature handling, and an honest applicability label. Verdict is NEEDS_REVIEW because the exact final-state input/output contract and physical assumptions are unspecified.

• P1V1/T1 = P2V2/T2 is the standard combined gas law for a fixed amount of an approximately ideal gas, but the specification does not state the required constant-amount and ideal-gas assumptions.
• The input description is ambiguous about which two final-state variables are supplied and how the missing final-state variable is selected or represented.
• The formula requires absolute temperature; temperatures entered in degrees Celsius must be converted to kelvins before calculation.

Units and conventions

• P1 and P2 must use the same pressure unit.
• V1 and V2 must use the same volume unit.
• T1 and T2 must be absolute temperatures in kelvins, or consistently converted from Celsius using T(K) = T(°C) + 273.15.
• The gas amount is constant between states and the gas is treated as ideal or sufficiently close to ideal.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "P1": 1,
    "V1": 2,
    "T1": 300,
    "V2": 1.5,
    "T2": 330,
    "pressure_unit": "atm",
    "volume_unit": "L",
    "temperature_unit": "K",
    "missing": "P2"
  },
  "expected_outputs": {
    "P2": 1.4666667,
    "pressure_unit": "atm"
  },
  "working": "P1V1/T1 = P2V2/T2. Rearrange: P2 = P1V1T2/(T1V2). Substitute: P2 = (1.00 atm × 2.00 L × 330 K)/(300 K × 1.50 L) = 660/450 atm = 1.4666667 atm."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The specification exposes invalid-input hazards at T=0 K and when P1*V1=0; these require rejection or an explicit undefined result. Pressure gauge-versus-absolute interpretation can also produce materially different outputs if the convention is not specified.

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
• BOUNDARY_HAZARD_CATALOG.json