Source: https://guthlabs.ai/docs/instruments/combined-combined-gas-law-calculator/mechanism/

instrument mechanism / verified-clean

# Combined/Combined-Gas-Law Calculator mechanism

The inspectable method record for Combined/Combined-Gas-Law Calculator, kept separate from implementation and qualification.

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

## 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

[01**Overview**](<https://guthlabs.ai/docs/instruments/combined-combined-gas-law-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/combined-combined-gas-law-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/combined-combined-gas-law-calculator/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-tranche4/tranche4-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`