hydrogen cyanide
Enable an AI agent to recognise hydrogen cyanide, assess its composition and physical state, and determine which handling or use decisions require verified evidence and authorised expertise.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
recalled by Codex without web access - no source was read
Researched by: Codex
Purpose and description
Enable an AI agent to recognise hydrogen cyanide, assess its composition and physical state, and determine which handling or use decisions require verified evidence and authorised expertise.
Hydrogen cyanide (HCN) is a highly toxic, volatile molecular compound with hydrogen-carbon-nitrogen connectivity that is a weak acid in water and is distinguished from cyanide ions and their salts.
It can be Resolve a name or identifier to hydrogen cyanide and flag confusion with cyanide salts or hydrogen isocyanide.; Assess whether analytical evidence adequately establishes composition and grade.; Check whether physical-property evidence applies to the recorded temperature, pressure and material form.; Compare documented exposure measurements with current, applicable limits using matching units and averaging periods.; Identify missing stability, compatibility or authorisation evidence and route consequential decisions to qualified personnel..
Distinguishing features
The molecular identity must resolve to HCN rather than the cyanide anion or a metal cyanide salt.
Molecular connectivity must distinguish hydrogen cyanide from hydrogen isocyanide; an elemental formula alone is insufficient.
An aqueous material must distinguish its hydrogen cyanide constituent from the solution as a whole and state the concentration basis.
A material capable of releasing hydrogen cyanide is not automatically a sample of hydrogen cyanide.
Gas-phase and liquid-phase records must be assessed against temperature, pressure and composition rather than treated as different substance identities.
Scope
+ Molecular identity and authoritative substance identifiers
+ Purity, water content, stabilisation and distinctions between neat substance and solutions
+ Physical phase and measured properties under stated conditions
+ Chemical stability, compatibility and changes in molecular form
+ Exposure evidence, hazard classifications and jurisdiction-specific controls
- The full cyanide family, including cyanide salts and coordination compounds
- Manufacturing routes, synthesis procedures and process optimisation
- Complete formulations and commercial products containing hydrogen cyanide
- Facility engineering and operating procedures
- Clinical diagnosis and treatment of cyanide poisoning
Characteristics
- Verified substance identity
- Molecular formula, connectivity, preferred name and verified CAS, PubChem and EC identifiers Prevents substitution of cyanide-family records or records for a different molecular connectivity.
- Material form
- Neat substance; aqueous solution constituent; gas-mixture constituent; other characterised mixture Determines whether evidence applies to the substance or to a containing material.
- Hydrogen cyanide content
- Mass fraction, mole fraction, mg/L or other explicit concentration basis, with method and uncertainty Makes grades, analytical results and mixture assessments interpretable.
- Water and impurity profile
- Identified constituents with mass fractions or trace concentrations and detection limits Supports evaluation of property data, suitability and stability evidence.
- Stabilisation status
- Verified stabilised; verified unstabilised; unknown; stabiliser identity, concentration and verification date Connects stability claims to the actual material and its documented condition.
- Physical state and conditions
- Gas, liquid, solid or multiphase; temperature in °C or K and pressure in kPa Prevents phase and handling assumptions based on an unspecified ambient condition.
- Phase-transition and volatility data
- Melting and boiling temperatures with pressure; vapour pressure in kPa at a stated temperature Supports assessment of state changes and potential airborne presence.
- Aqueous speciation evidence
- pH, temperature, analytical species and applicable equilibrium data Distinguishes molecular HCN measurements from cyanide-ion and total-cyanide measurements.
- Stability and compatibility assessment
- Documented applicable conditions; evidence date; assessed, unresolved or outside documented conditions Prevents a generic substance record from being treated as proof that a particular sample is suitable for handling.
- Exposure measurement
- ppm or mg/m³, with sampling location, duration, method, detection limit and calibration status Makes airborne measurements comparable with correctly matched exposure criteria.
- Applicable hazard and regulatory record
- Links to authoritative classifications, exposure limits, transport entries and site authorisations, each with jurisdiction and effective date Ensures decisions use controls applicable to the material form, location and intended activity.
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.hydrogen-cyanide
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 19 findings · 31 questions.
Hydrogen cyanide identity Establish the molecular substance and its relationship to broader cyanide records and containing materials.
Hydrogen cyanide needs a narrower identity than cyanide while retaining links to shared family concepts.
Molecular and regulatory identity
Resolve names and identifiers against molecular connectivity.
Identity resolution evidence
Record evidence that identifiers and names refer to hydrogen cyanide with the intended connectivity and material scope.
- Which authoritative records establish the molecular connectivity and CAS, PubChem and EC identifiers for hydrogen cyanide? provenance
- Does each candidate record describe hydrogen cyanide, hydrogen isocyanide, a cyanide salt or a containing mixture? boundary
Cyanide family and mixture boundary
Keep shared cyanide concepts and solution identities at their appropriate scope.
Substance versus containing material
Represent hydrogen cyanide as a defined substance or constituent without assigning its identity to every cyanide-bearing material.
- Which concepts should be inherited or linked from the broader cyanide model, and which depend specifically on molecular HCN? boundary
- When a record uses the name hydrocyanic acid, what concentration and solution context does its source specify? definition
Composition and speciation Describe hydrogen cyanide content, analytical meaning and constituents that qualify a material's grade.
A nominal hydrogen cyanide label cannot establish purity, solution composition or which cyanide species an assay measured.
Grade and constituents
Characterise purity, water, impurities and declared stabilisation.
Sample composition evidence
Attach composition claims to a specific sample or lot, analytical method and reporting basis.
- What hydrogen cyanide content and water content were measured, using which methods, units and uncertainties? measurement
- Which impurities or stabilisers are documented for this lot, and how recently was their presence verified? provenance
Aqueous species and assay meaning
Distinguish molecular HCN from other cyanide species in analytical and equilibrium records.
Species-specific interpretation
Require enough analytical and solution context to interpret a reported cyanide result.
- Does the reported assay quantify molecular hydrogen cyanide, free cyanide, total cyanide or another method-defined fraction? definition
- What pH, temperature and matrix information are available to support interpretation of the aqueous species present? measurement
Phase and volatility Relate hydrogen cyanide's observed state and tendency to enter the gas phase to documented conditions.
State and volatility evidence must be tied to temperature, pressure and composition before it can inform a decision.
Condition-dependent phase
Connect phase observations with applicable transition data.
Phase assignment
Record the observed phase and the conditions needed to interpret it.
- What phase was observed, at what temperature and pressure, and for what composition? measurement
- Which verified melting and boiling data apply to this material, and what pressure and purity qualifications accompany them? provenance
Vapour and mixture behaviour
Separate pure-substance volatility data from gas mixtures and aqueous-system evidence.
Volatility evidence applicability
Qualify vapour-pressure and partitioning information by the system it describes.
- What vapour-pressure or gas-liquid partitioning measurements are available at the relevant temperature and composition? measurement
- Does the cited evidence describe neat hydrogen cyanide, an aqueous solution or a gas mixture, and is that scope applicable here? boundary
Stability and compatibility Track evidence concerning hydrogen cyanide stability, stabilisation and contact-material compatibility.
Identity and purity alone do not establish whether a material remains within its documented handling conditions.
Stability and material history
Relate stability assessments to the actual lot and its history.
Documented stability status
Record source-backed stability qualifications and unresolved departures from them.
- What authoritative evidence addresses polymerisation, decomposition and the role of stabilisation for the supplied material? provenance
- Does the recorded age, composition and storage history remain within the supplier's documented conditions, or require expert reassessment? action
Contact and reaction boundaries
Link contact-material and chemical compatibility claims to a defined application.
Compatibility evidence
Require applicable compatibility evidence before accepting a proposed contact or use.
- Which authoritative compatibility records cover the proposed contact materials and the hydrogen cyanide form involved? provenance
- What missing composition or condition information prevents a qualified reviewer from accepting the proposed use? action
Hazards, exposure and controls Connect hydrogen cyanide hazard evidence, exposure measurements and applicable authorisations.
Hazard labels and exposure criteria require material-specific and jurisdiction-specific interpretation.
Hazard and exposure evidence
Record verified classifications and interpretable monitoring results.
Classification and monitoring
Maintain hazard classifications and exposure evidence with their scope, date and measurement limitations.
- Which current authoritative classifications apply to this form and concentration of hydrogen cyanide, including acute toxicity and physical hazards? provenance
- What monitoring method, calibration, sampling period and detection limit support each airborne hydrogen cyanide measurement? measurement
- Which applicable exposure limits and skin notations must be considered, and do the measurement units and averaging periods match? boundary
Authorised activity and escalation
Identify the controls and responsible roles governing a proposed activity.
Decision authority
Link consequential actions to applicable transport, workplace and emergency requirements.
- Which jurisdiction-specific transport entry and workplace requirements apply to the material's form, concentration and proposed activity? boundary
- What verified site authorisation and qualified review are required before the proposed activity may proceed? action
- Which approved site emergency plan and responsible personnel govern escalation of a suspected release or exposure? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Check these first
Recalled without web access and unsourced; every item is a lead to verify.
- This is recall-based information; no sources were consulted.
- Check current jurisdiction-specific hazard classifications, exposure limits and transport entries before regulatory use.
- Physical constants describe the pure substance under stated conditions; aqueous concentration, impurities and stabilizers affect material behavior.
- Which of these check these first hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Anhydrous hydrogen cyanide
- Aqueous hydrogen cyanide, commonly called hydrocyanic acid
- Which of these kinds and varieties hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Identifiers and schemes
Recalled without web access and unsourced; every item is a lead to verify.
- CAS Registry Number - 74-90-8 - Identifies hydrogen cyanide; solution concentration and formulation require separate description.
- PubChem CID - 768 - Compound identifier for hydrogen cyanide.
- EC number - 200-821-6 - European chemical inventory identifier.
- Molecular formula - HCN - Formula alone does not distinguish hydrogen cyanide from its connectivity isomer hydrogen isocyanide.
- Which of these identifiers and schemes hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Standards and regulation
Recalled without web access and unsourced; every item is a lead to verify.
- United Nations Globally Harmonized System of Classification and Labelling of Chemicals provides the framework for communicating acute toxicity and flammability hazards.
- European Union CLP Regulation governs substance and mixture classification, labelling and packaging.
- United Nations Recommendations on the Transport of Dangerous Goods distinguish transport descriptions according to concentration and stabilization.
- Which of these standards and regulation hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Industrial intermediate for adiponitrile used in nylon manufacture.
- Feedstock for acetone cyanohydrin in a route to methyl methacrylate.
- Manufacture of cyanide salts and other chemical intermediates.
- Historically used as a fumigant.
- Which of these real-world use hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Molar mass - 27.03 - g/mol
- Melting point of pure substance - Approximately -13.4 - °C
- Normal boiling point at 101.325 kPa - Approximately 25.6 - °C
- Acid dissociation constant, pKa, in water near 25 °C - Approximately 9.2 - dimensionless
- Which of these typical measurements hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Failure modes and hazards
Recalled without web access and unsourced; every item is a lead to verify.
- Acute poisoning can follow inhalation, ingestion or skin absorption; cyanide inhibits mitochondrial cytochrome c oxidase and impairs cellular oxygen use.
- High volatility can rapidly create dangerous airborne concentrations.
- Highly flammable; vapor mixed with air can present a fire or explosion hazard.
- Uncontrolled polymerization can release heat and generate pressure, particularly when stabilization or storage conditions are inadequate.
- Its reported bitter-almond odor is an unreliable warning because detection varies between people.
- Which of these failure modes and hazards hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Occupational exposure limits, averaging periods and skin notations differ among jurisdictions and issuing bodies.
- GHS implementation and requirements for transport, storage and permitted uses vary by jurisdiction.
- Which of these regional variation hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Recalled without web access and unsourced; every item is a lead to verify.
- cyanide - Cyanide is the broader registry concept encompassing the CN− ion and related substances; hydrogen cyanide is the specific neutral HCN molecule.
- hydrocyanic acid - Usually denotes hydrogen cyanide dissolved in water; concentration and solution properties distinguish it from anhydrous HCN.
- sodium cyanide - An ionic salt containing Na+ and CN−, rather than the neutral molecular compound HCN.
- hydrogen isocyanide - Has H-N-C connectivity rather than hydrogen cyanide's H-C-N connectivity.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of hydrogen cyanide this model covers, and on what evidence? provenance
What the second pass must settle
- Does an existing Vercy world model already own hydrogen cyanide, and which broader cyanide publication should this registry entry reference?
- Which authoritative identity records resolve identifiers and the naming boundary between hydrogen cyanide and hydrocyanic acid?
- Which reference datasets provide defensible physical constants and aqueous equilibrium data with conditions and uncertainties?
- What supplier-specific evidence is necessary to establish stabilisation, stability and compatibility for different grades and material forms?
- Which jurisdictions and intended activities determine the hazard classifications, exposure limits, transport entries and authorisations this model must support?