Buffer Capacity Estimator 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

t4-075

Effect

Computation or source lookup only

Input and validation requirements

A zero total concentration produces the undefined expression 0/0, so the estimator requires explicit input rejection. The sign convention for pH-pKa is also not specified, creating a species-label ambiguity even though beta is symmetric and numerically unchanged.

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": {
    "pKa": 4.76,
    "pH": 4.76,
    "total_buffer_concentration": 100,
    "concentration_unit": "mM"
  },
  "expected_outputs": {
    "beta_mol_L_per_pH": 0.057575,
    "effective_range_pH": {
      "lower": 3.76,
      "upper": 5.76
    }
  },
  "working": "Convert concentration: C_total=100 mM/1000=0.100 M. pH−pKa=4.76−4.76=0, so r=10^0=1. alpha_HA=1/(1+1)=0.5. alpha_A−=1/(1+1)=0.5. Species-product fraction=0.5×0.5=0.25. beta=2.303×0.100×0.25=0.057575 mol/L per pH. Range lower=4.76−1=3.76; upper=4.76+1=5.76."
}

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