Source: https://guthlabs.ai/docs/instruments/molality-calculator/mechanism/

instrument mechanism / verified-clean

# Molality Calculator mechanism

The inspectable method record for Molality Calculator, kept separate from implementation and qualification.

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

## Model scope

The core formula is correct for mole input and kilogram solvent input. The specification needs an explicit input mode and, for mass-based solute input, a required molar-mass conversion. Until those units and requirements are defined, the catalog claim is ambiguous.

- The formula m = n_solute / kg_solvent is the standard molality formula only when n_solute is in moles and solvent mass is in kilograms.

- The declared input of solute mass is unsupported by the stated formula unless molar mass is also provided and the conversion n_solute = solute_mass / molar_mass is performed.

- The input unit for solvent mass is not specified; using grams directly instead of converting to kilograms produces an incorrect result.

## Units and conventions

- n_solute is measured in mol.

- kg_solvent is the mass of solvent measured in kg, not the mass of the solution.

- If solute mass is supplied, its unit and the solute molar mass must be supplied so mass can be converted to moles.

- The output unit is mol/kg, conventionally written mol kg^-1.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "solute_moles": 0.5,
    "solvent_mass_kg": 2
  },
  "expected_outputs": {
    "molality_mol_per_kg": 0.25
  },
  "working": "m = n_solute / kg_solvent\nm = 0.500 mol / 2.000 kg\nm = 0.250 mol/kg"
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The calculator has an undefined result when solvent mass is zero, should reject nonpositive solvent masses, and can produce a 1000-fold discrepancy when the solvent-mass unit is not specified.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/molality-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/molality-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/molality-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`