Osmolarity / Tonicity 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

t4-170

Effect

Computation or source lookup only

Input and validation requirements

The plain-arithmetic implementation can return Infinity for extreme finite inputs instead of rejecting them. The specification also omits the tonicity reference threshold and explicit concentration units, allowing classification and numerical interpretation ambiguities.

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": {
    "mode": "solution",
    "solutes": [
      {
        "name": "NaCl",
        "molarity_mol_per_L": 0.154,
        "dissociation_factor": 2
      }
    ]
  },
  "expected_outputs": {
    "osmolarity_Osm_per_L": 0.308,
    "osmolarity_mOsm_per_L": 308,
    "tonicity_label": "not determinable from total osmolarity alone"
  },
  "working": "Osm = 0.154 mol/L × 2 = 0.308 Osm/L. Convert to mOsm/L: 0.308 × 1000 = 308 mOsm/L. A tonicity label is not assigned because membrane permeability and the reference condition are unspecified."
}

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