Home Developers Capabilities Henderson–Hasselbalch

CVP verified calculation capability

Henderson–Hasselbalch Calculation Capability

Buffer pH = pKa + log10([A−]/[HA]). Accepts pKa or Ka. Not ICE and not pH = −log10[H+].

Chemistry · Acid Base Capability ID chemistry.acid_base.henderson_hasselbalch version 1.0.1 CVP VERIFIED CURRENT Engineering

Model

Henderson–Hasselbalch

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

SymbolQuantityUnitRole
pKaAcid dissociation pKa—input / output
KaAcid dissociation constant—input / output
HAWeak-acid concentration of the conjugate pair—input / output
AConjugate-base concentration of the pair—input / output
pH——output
ratio——output
model——output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

Not supported

Example

One numerical check. The calculator page holds worked steps and FAQ.

pKa=5 HA=0.1 A=0.2 → pH=5+log10(2)

Open this example in the calculator

Trust

CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance · Buffer pH = pKa + log10(A/HA), with pKa or Ka, + O3 mpmath tabulated buffer pH.. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.

CVP
CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance · Buffer pH = pKa + log10(A/HA), with pKa or Ka, + O3 mpmath tabulated buffer pH.· View Manifest · CVP overview · Specification
Verified scope
Buffer pH = pKa + log10(A/HA), with pKa or Ka, + O3 mpmath tabulated buffer pH.
Assurance
Engineering
Declared partition coverage
PASS · 7/7 declared partitions (alias, ka, awkward, equal, acid, base, invalid-domain)
Deferred
Not an ICE table and not pH = −log10[H+].
Calculation version
1.0.1
Verification
11/11 calculation tests · 1/1 legacy golden · 5/5 legacy boundary · 5/5 legacy property
Production surface contract
6/6
Versions
Calculation 1.0.1 · CVP protocol 1.0.0-proposed · Evidence 2026-09-25.o2-o3.2
Verification revision
2026-09-25.o2-o3.2 · 1/1 property · digest 2125ba6d5a14
Reference
O1 model · O3 expected_values · O3 numerical_behavior · O2 expected_values · O2 numerical_behavior
Numerical scope
O2: Henderson–Hasselbalch pH vs a separate-module identity (≤2 ULP). Not an ICE table. ≤2 ULP vs O3 applies only to the published tabulated buffer vectors. Not an ICE table.
Interfaces
PASS · UI (SSR) / REST / MCP
ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only.
CVP suite
4/4 golden · 5/5 CVP boundary · 5/5 invalid · 1/1 property · 1/1 metamorphic · 8/8 O3 · 2/2 cross-interface · 6/6 CVP contract
Supplemental domain review
Not performed
Named expert review
Not performed
Version lock
Supported (409 VERSION_MISMATCH)
Artifact consistency
Build verified · 1.0.1 (workspace artifacts agree)
Review-policy tier
Engine tested — catalog token engine_tested; supplemental; not CVP status
This calculator CURRENT · Public schema 1.0.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.

curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/henderson-hasselbalch' \
  -H 'Content-Type: application/json' \
  -d '{"inputs":{"pKa":5,"HA":0.1,"A":0.2},"calculation_version":"1.0.1"}'

POST /api/v1/calc/henderson-hasselbalch. This is a POST calculate endpoint — do not GET it.

Full REST contract: REST API docs.

Tool id
henderson-hasselbalch
Engine
henderson-hasselbalch
REST
POST /api/v1/calc/henderson-hasselbalch
MCP
execute_calculation with capability_id: "chemistry.acid_base.henderson_hasselbalch"
Agent input schema
Canonical (MCP / Agent)
Output schema
JSON Schema (latest)
Versioned input schema
Immutable pin (1.0.1)
Versioned output schema
Immutable pin (1.0.1)

References

Human-readable sources plus CVP reference evidence classes.

Sources

Reference evidence classes: O1 model · O3 expected_values · O3 numerical_behavior · O2 expected_values · O2 numerical_behavior

Try with an agent

Inspect, then execute. Same engine as REST and the human calculator.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"chemistry.acid_base.henderson_hasselbalch"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

Pin calculation_version (1.0.1) when the result must stay reproducible.

Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.