Public evidence

chemistry.equilibrium.weak_acid

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

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Verification

12/12 calculation tests · Production surface contract 4/4

Golden tests 2 / 2
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: STALE · Last attested schema matched 1.0.0 snapshot / local build · Semantic contract ✓ · Last attestation PASS · current evidence changed · re-attestation required · Public/cache ✓ · Origin ✓ · Live production status PASS (0 stale; 163 CURRENT) @ 2026-09-17T03:09:03.307Z
Semantic contract PASS
Evidence attested at 2026-09-17T03:09:02.494Z
Last production check 2026-09-17T03:09:02.494Z
Public / cache PASS
Origin PASS
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 sha256:0487fdb858a23b1d782f18415e706a34132a45f9e48fe10d08e4dfbbf371dd0c

Input schema sha256:60ff18a4d6d5899bf55418bf655d5702e0b089931be5ccb436fb0eafa61368bb · Output schema sha256:3c2fb62806717f9fc7bcf1a90ffb2771dd11857fc3cb2809dae93fec150200b9 · 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: weak-acid-equilibrium
Engine: weak-acid-equilibrium
Engine build: 2026-09-17
Evidence core: 2026-09-17T01:05:58.494Z
Rendered: 2026-09-17T02:45:35.819Z
Last reviewed: —

Assumptions

Monoprotic HA ⇌ H+ + A−
Activity coefficients ≈ 1
Kw = 1e-14 at 25 °C when mode=ice
Not Henderson–Hasselbalch
Not pH = −log10[H+] identities
Not polyprotic, not a weak base, not titration

Limitations

Monoprotic HA only; not polyprotic, not a weak base, not activity coefficients
Not Henderson–Hasselbalch (buffer pair as given)
Not the water-ion identity page pH=−log10[H+]
Kw = 1e-14 at 25 °C when mode=ice

Sources

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

OpenStax Chemistry 2e — Weak Acids — Equilibrium of a weak acid
Supports: Ka = [H+][A−]/[HA]; ICE from formal C; dilute water may include Kw
IUPAC Gold Book — acid dissociation constant — acidity constant
Supports: Ka is the equilibrium constant for HA ⇌ H+ + A−

Published checks

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

ID	Kind	Status	Detail
`golden-ice-no-water`	golden	pass	Expected h=0.001332670973077975 · A=0.001332670973077975 · model=weak_acid_ice · include_water=false · Actual mode=ice_no_water · pH=2.8752770612235934 · h=0.00133267097408 · HA=0.09866732902592 · A=0.00133267097408 · oh=7.503727622568977e-12 · C=0.1 · Ka=0.000018
`golden-ice-water`	golden	pass	Expected model=weak_acid_ice · include_water=true · C=0.1 · Actual mode=ice · pH=2.875276773863538 · h=0.00133267185587 · HA=0.09866732815163373 · A=0.0013326718483662773 · oh=7.503722657571816e-12 · C=0.1 · Ka=0.000018
`boundary-ice-pka`	boundary	pass	Expected pKa=5 · model=weak_acid_ice · Actual mode=ice · pH=3.0021707531304345 · h=0.000995014127135 · HA=0.09900498588291512 · A=0.0009950141170848915 · oh=1.0050108563577444e-11 · C=0.1 · Ka=0.000009999999999999999
`boundary-ice-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-ice-c`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`boundary-ice-mixed`	boundary	pass	Expected MIXED_INPUT_ENCODING · Actual MIXED_INPUT_ENCODING
`boundary-ice-hh`	boundary	pass	Expected INVALID_MODE · Actual INVALID_MODE
`property-ice-quad`	property	pass	x^2+Ka x=Ka C
`property-ice-mass`	property	pass	C=[HA]+[A−]
`property-ice-charge`	property	pass	[H+]=[A−]+[OH−]
`property-ice-model`	property	pass	weak_acid_ice
`property-ice-pka`	property	pass	pKa encoding