Source: https://guthlabs.ai/docs/instruments/ph-poh-calculator/implementation/

instrument implementation / implementation-contract

# pH / pOH Calculator implementation

A source-bound implementation contract for pH / pOH Calculator; 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**: t6-038

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification does not define validation or rejection behavior for zero or negative concentrations, although these inputs cause division by zero or logarithms outside the real domain. It also leaves concentration units implicit, allowing a 3-pH-unit discrepancy for the same displayed numeric input.

## 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": {
    "pH": "0.00"
  },
  "expected_outputs": {
    "pOH": "14.000000",
    "[H+]_mol_per_L": "1.000000×10^0",
    "[OH-]_mol_per_L": "1.000000×10^-14"
  },
  "working": "pOH = 14.000000 - pH = 14.000000 - 0.000000 = 14.000000.\n[H+] = 10^(-pH) = 10^0 = 1.000000 mol/L.\n[OH-] = Kw/[H+] = (1.000000×10^-14)/(1.000000) = 1.000000×10^-14 mol/L.\nThis is a boundary-like case: pH=0 is valid mathematically, but represents an idealized 1 mol/L hydrogen-ion concentration."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/ph-poh-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/ph-poh-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/ph-poh-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-tranche6/tranche6-results.json`