Percent Solution / Concentration Unit Converter

Inspectable records

Ledger state

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

Area

Biology, Medicine & Pharmacology (educational estimates only — every panel labeled not-medical-advice)

Tranche

tranche-5

Evidence ID

t5-202

Ledger rows

1

No ledger note is attached.

Review findings

The listed instrument behavior is not fully verifiable because the spec lacks explicit formulas and does not define the basis of ppm or the density convention. The exact ambiguities requiring resolution are: ppm basis (w/w, v/v, or mg/L), which density applies in each mass-volume conversion, required units and validation for MW/density, and the direction-specific formulas for every supported unit pair.

Formula and scope findings

• The formula specification is not explicit: "cross-unit conversions via density/MW where applicable" does not define the direction-specific equations or the exact density relationships.
• ppm is ambiguous because it may mean ppm by mass (mg/kg), ppm by volume (µL/L), or, in aqueous contexts, mg/L. The target unit must specify its basis.
• %w/v to mg/mL has the standard relation 1% w/v = 1 g/100 mL = 10 mg/mL.
• %v/v to ppm is only directly convertible when ppm is explicitly ppm v/v: x% v/v = 10,000x ppm v/v.
• Molarity to mg/mL uses mg/mL = mol/L × molecular weight in g/mol; the MW input must be for the exact chemical species and formula state.
• Conversions involving %v/v and mass-based units require a clearly defined density, generally solution density for mass concentration of solution and/or pure-solute density for solute volume. The required density is not specified.

Unit assumptions

• %w/v means grams of solute per 100 mL of final solution.
• %v/v means milliliters of solute per 100 mL of final solution.
• Molarity means moles of solute per liter of final solution.
• For the molarity test, MW is in g/mol and the exact compound has MW 58.44 g/mol.
• For the %v/v-to-ppm test, ppm is interpreted as ppm v/v, meaning volume fraction × 1,000,000.
• For the mg/mL-to-ppm test, ppm is interpreted as aqueous-equivalent mg/L, using solution density 1.000 kg/L; this is not generally valid for nonaqueous or concentrated solutions.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

A zero density creates a genuine division-by-zero case that must be rejected. The ppm test also exposes a convention hazard: aqueous ppm and mass-based ppm produce different results when density is not 1.0.

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": {
    "value": 1,
    "source_unit": "%w/v",
    "target_unit": "mg/mL"
  },
  "expected_outputs": {
    "value": 10,
    "unit": "mg/mL"
  },
  "working": "1% w/v = 1 g per 100 mL. 1 g = 1000 mg, so 1 g/100 mL = 1000 mg/100 mL = 10 mg/mL."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

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-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json