pH / Henderson-Hasselbalch Calculator mechanism

Model scope

The chemistry formula is valid under its stated assumptions, and the existing educational/not-medical-advice label is appropriate. Review is required to define the buffer-capacity note and to specify whether blood calculations accept dissolved CO2 concentration or PCO2, including the required units and coefficient.

• pH=pKa+log10([A-]/[HA]) is the standard Henderson-Hasselbalch equation for a conjugate acid-base pair, provided the ratio is dimensionless and concentrations are positive.
• The claimed 'buffer capacity note' has no definition or formula, so that output cannot be verified or reproducibly generated.
• The phrase 'acid-base blood parameter estimate' is ambiguous: clinical bicarbonate systems commonly use pH=6.1+log10([HCO3-]/(0.03×PCO2)) when PCO2 is supplied in mmHg, whereas the stated concentration-ratio formula requires dissolved CO2 concentration as [HA].

Units and conventions

• log means base-10 logarithm.
• [A-] and [HA] must be expressed in the same concentration units, or converted before division; their ratio is dimensionless.
• pKa is dimensionless and must correspond to the specified acid-base pair and relevant temperature, ionic strength, and chemical conditions.
• For bicarbonate blood calculations using PCO2 rather than dissolved CO2 concentration, the applicable coefficient and PCO2 units must be explicitly specified.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "pKa": 4.76,
    "conjugate_base": "0.100 mol/L acetate",
    "conjugate_acid": "0.100 mol/L acetic acid"
  },
  "expected_outputs": {
    "pH": 4.76
  },
  "working": "A-/HA = 0.100 mol/L ÷ 0.100 mol/L = 1. pH = 4.76 + log10(1) = 4.76 + 0 = 4.76."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero conjugate-acid concentration causes division by zero, making the pH undefined; the instrument must reject the input rather than force a numeric result. There is also a convention hazard if the ratio direction or logarithm base is not made explicit.

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
• BOUNDARY_HAZARD_CATALOG.json