Public evidence

chemistry.acid_base.ph

Machine-checked verification for calculation version 1.0.0 · tier engine_tested

Open calculator API Capability Download JSON MCP Review policy

Verification

14/14 calculation tests · Production surface contract 3/3

Golden tests 1 / 1
Boundary tests 7 / 7
Property tests 6 / 6
Production surface contract 3 / 3
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Production attestation Embedded snapshot: unpublished · Build schema 1.0.0 ready · Semantic contract ✓ · Attestation report not published on origin · Live production status PASS (0 stale; 164 CURRENT) @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

Fingerprint sha256:3db329ddc99d9bae43c2fe3739f1a31e12a724fc11607b4b62bc926b5341c1f7

Input schema sha256:aa1d41479ee00f117f3801fcbb95513c05cf476041c9a429aeb81387e33a0bbb · Output schema sha256:9e6b732828f2878b79d7197921d719923b25926ab207aac316866b2cb13dee5b · 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: ph
Engine: ph
Engine build: 2026-09-16
Evidence core: 2026-09-16T11:27:17.156Z
Rendered: 2026-09-16T11:29:50.773Z
Last reviewed: —

Assumptions

pH = −log10[H+]
pOH = −log10[OH−]
Kw = 1e-14 at 25 °C
Not Henderson–Hasselbalch
Not ICE or activity coefficients

Limitations

Kw = 1e-14 at 25 °C (not temperature-dependent)
Not Henderson–Hasselbalch buffer pH
Not ICE, 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 — pH and pOH — pH and pOH
Supports: pH = −log10[H3O+]; pOH = −log10[OH−]; pH + pOH = 14 at 25 °C
IUPAC Gold Book — pH — pH
Supports: pH is defined from hydrogen-ion activity; dilute water uses −log10[H+]

Published checks

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

ID	Kind	Status	Detail
`golden-ph`	golden	pass	Expected pH=3 · pOH=11 · model=water_ion_product · Actual mode=ph_from_h · pH=3 · h=0.001 · pOH=11 · oh=1e-11 · Kw=1e-14 · pKw=14 · T_C=25
`boundary-ph-from-ph`	boundary	pass	Expected pH=3 · Actual mode=h_from_ph · pH=3 · h=0.001 · pOH=11 · oh=1e-11 · Kw=1e-14 · pKw=14 · T_C=25
`boundary-ph-poh-oh`	boundary	pass	Expected pOH=3 · pH=11 · Actual mode=poh_from_oh · pH=11 · h=1e-11 · pOH=3 · oh=0.001 · Kw=1e-14 · pKw=14 · T_C=25
`boundary-ph-from-poh`	boundary	pass	Expected pH=3 · Actual mode=ph_from_poh · pH=3 · h=0.001 · pOH=11 · oh=1e-11 · Kw=1e-14 · pKw=14 · T_C=25
`boundary-ph-poh-from-ph`	boundary	pass	Expected pOH=11 · Actual mode=poh_from_ph · pH=3 · h=0.001 · pOH=11 · oh=1e-11 · Kw=1e-14 · pKw=14 · T_C=25
`boundary-ph-zero`	boundary	pass	Expected VALUE_MUST_BE_POSITIVE · Actual VALUE_MUST_BE_POSITIVE
`boundary-ph-missing`	boundary	pass	Expected MISSING_REQUIRED_INPUT · Actual MISSING_REQUIRED_INPUT
`boundary-ph-hh`	boundary	pass	Expected INVALID_MODE · Actual INVALID_MODE
`property-ph-from-h`	property	pass	pH=3
`property-ph-poh`	property	pass	pH+pOH=14
`property-ph-h`	property	pass	[H+]=10^(−pH)
`property-ph-oh`	property	pass	pOH=3
`property-ph-sum`	property	pass	pH=14−pOH
`property-ph-model`	property	pass	water_ion_product