Source: https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter/implementation/

instrument implementation / implementation-contract

# Percent Solution / Concentration-Unit Converter implementation

A source-bound implementation contract for Percent Solution / Concentration-Unit Converter; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## 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**: t3-015

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification exposes two concrete failure hazards: 100% w/w causes division by zero in molality, and several requested conversions, especially %v/v, are underdetermined without solute density. ppm-to-molarity also changes from an approximate dilute-aqueous branch to a density-corrected branch when density is supplied.

## 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": {
    "solute_mass_g": 5,
    "solution_volume_mL": 100,
    "solute_molar_mass_g_per_mol": 58.44,
    "medium": "dilute aqueous"
  },
  "expected_outputs": {
    "percent_w_v": 5,
    "solute_mass_g_per_L": 50,
    "molarity_mol_per_L": 0.855578
  },
  "working": "%w/v=(5 g/100 mL)×100=5% w/v. 100 mL=0.100 L, so 5 g/0.100 L=50 g/L. Molarity=50 g/L ÷ 58.44 g/mol=0.855578 mol/L. Under the dilute-aqueous assumption, ppm=50 g/L×1000 mg/g=50000 mg/L=50000 ppm."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter/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-tranche3/tranche3-results.json`