Public evidence

chemistry.acid_base.henderson_hasselbalch

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

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Verification

11/11 calculation tests · Production surface contract 4/4

Golden tests 1 / 1
Boundary tests 5 / 5
Property tests 5 / 5
Production surface contract 4 / 4
Engine tested Yes
Source checked Yes
Artifact integrity PASS
Production attestation Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status PASS (0 stale; 164 CURRENT) @ 2026-09-16T06:44:24.909Z
Semantic contract PASS
Evidence attested at 2026-09-16T06:44:24.203Z
Last production check 2026-09-16T06:44:24.203Z
Public / cache —
Origin —
Supplemental domain review Not performed
Named expert review Not performed

release artifacts aligned PASS
schema valid input executes PASS
engine success output validates schema PASS
schema rejects incomplete input PASS

Fingerprint sha256:5c7630641001622bbc72af7da46a440155d493a7e0c882f5cb5f01120b9235e5

Input schema sha256:f0b0289022c148bec4b0739d920e5562090582a1e0e8ae56ba5806785179efa6 · Output schema sha256:45b6ae449f91891986b9f608b2c581ee5b8701f3de2dd95bcc44625cb6c13dfc · Build-time SHA-256 digests prove published artifacts agree with each other (release_integrity.scope=workspace). Production attestation GETs canonical URLs twice (public/cached view and origin), including Capability HTML, via npm run attest:production --write (published at /.well-known/calculatorx-production-attestation.json) and fails if the public Capability page advertises a different calculation_version. This is artifact consistency, not an independent immutable release log.

Build & scope

Engine identity and declared limitations.

Tool: henderson-hasselbalch
Engine: henderson-hasselbalch
Engine build: 2026-09-16
Evidence core: 2026-09-16T11:18:24.767Z
Rendered: 2026-09-16T11:29:50.772Z
Last reviewed: —

Assumptions

Monoprotic buffer; HA and A− are the pair as given
Activity coefficients ≈ 1
Not ICE equilibrium
Not pH = −log10[H+]
Not polyprotic

Limitations

Monoprotic buffer pair as given — not ICE equilibrium
Not pH = −log10[H+]
Not activity coefficients or polyprotic

Sources

Standards and references supporting this tool specification. Methods are listed separately — they are algorithms, not bibliographic sources.

OpenStax Chemistry 2e — Acid-Base Buffers — Henderson–Hasselbalch equation
Supports: pH = pKa + log10([base]/[acid]) for a conjugate pair
IUPAC Gold Book — buffer solution — conjugate acid–base pair
Supports: A buffer is a conjugate acid–base pair whose ratio sets pH

Published checks

Golden, boundary, and property cases included in this evidence build.

ID	Kind	Status	Detail
`golden-hh`	golden	pass	Expected pH=5.301029995663981 · pKa=5 · HA=0.1 · A=0.2 · ratio=2 · model=henderson_hasselbalch · Actual pH=5.301029995663981 · pKa=5 · Ka=0.000009999999999999999 · HA=0.1 · A=0.2 · ratio=2 · model=henderson_hasselbalch
`boundary-hh`	boundary	pass	Expected pH=5 · ratio=1 · Actual pH=5 · pKa=5 · Ka=0.000009999999999999999 · HA=0.1 · A=0.1 · ratio=1 · model=henderson_hasselbalch
`boundary-hh-ka`	boundary	pass	Expected pH=5.301029995663981 · pKa=5 · Actual pH=5.301029995663981 · pKa=5 · Ka=0.00001 · HA=0.1 · A=0.2 · ratio=2 · model=henderson_hasselbalch
`boundary-hh-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-hh-ha`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`boundary-hh-mixed`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`property-hh-ph`	property	pass	5+log10(2)
`property-hh-ratio`	property	pass	2
`property-hh-equal`	property	pass	pH=pKa
`property-hh-ka`	property	pass	Ka→pKa
`property-hh-model`	property	pass	henderson_hasselbalch