Source: https://guthlabs.ai/docs/instruments/ka-kb-pka-pkb-converter/implementation/

instrument implementation / implementation-contract

# Ka/Kb ⇄ pKa/pKb Converter implementation

A source-bound implementation contract for Ka/Kb ⇄ pKa/pKb 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**: t4-039

**Effect**: Computation or source lookup only

## Input and validation requirements

- Ka=0 or Kb=0 causes division by zero when deriving the conjugate constant and makes the logarithm undefined.

- Negative Ka, Kb, or Kw values are invalid for these logarithms and equilibrium-constant calculations.

- The implementation must reject missing, nonnumeric, NaN, infinite, zero, or negative equilibrium constants when logarithms or reciprocal conversions are required.

- Using a default Kw without displaying or documenting its temperature can produce materially incorrect results.

- Inputs with concentration units are an ambiguity or unit-conversion trap unless the standard-state convention is explicitly defined.

## 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": {
    "Ka": 0.00001
  },
  "expected_outputs": {
    "Ka": 0.00001,
    "pKa": 5,
    "Kb": 1e-9,
    "pKb": 9
  },
  "working": "1. pKa=-log10(1×10^-5)=5. 2. Kb=Kw/Ka=(1×10^-14)/(1×10^-5)=1×10^(-14+5)=1×10^-9. 3. pKb=-log10(1×10^-9)=9."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/ka-kb-pka-pkb-converter/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/ka-kb-pka-pkb-converter/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/ka-kb-pka-pkb-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-tranche4/tranche4-results.json`