{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.hypophosphoric-acid","code":"thing-q4492149","url":"https://ver.cy/models/thing/q4492149/","name":"hypophosphoric acid","alternateNames":[],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.MAT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"Hypophosphoric acid is a phosphorus oxoacid of formula H4P2O6, with a direct phosphorus-phosphorus bond and each phosphorus atom in oxidation state +4, that forms hypophosphate salts.","purpose":"Enable an AI agent to recognise hypophosphoric acid, assess the identity and condition of a particular sample, and determine which analytical or handling actions its evidence supports.","scope":{"in":["Molecular identity and differentiation from similarly named phosphorus oxoacids","Anhydrous, hydrated and dissolved forms with explicit composition","Acid content, water content and phosphorus-containing impurities","Protonation state and acid-base behaviour under recorded solution conditions","Evidence for structural integrity, transformations and sample ageing","Substance-specific hazard evidence and sample suitability"],"out":["Hypophosphorous acid, phosphorous acid and phosphoric acid as independently modelled substances","Hypophosphate salts as independently supplied substances","Isohypophosphoric acid as a separate structural identity","Manufacturing plants and synthesis processes","Commercial formulations containing hypophosphoric acid beyond their relationship to this constituent"],"boundaries":[]},"distinguishingFeatures":["Require the H4P2O6 identity and direct phosphorus-phosphorus connectivity; a matching name alone is insufficient. The identity record encodes this connectivity: [PubChem](https://pubchem.ncbi.nlm.nih.gov/compound/Hypophosphoric-acid).","Reject confusion with hypophosphorous acid: verify the complete formula and structure rather than accepting the near-identical name or an abbreviation.","Require evidence distinguishing the direct P-P structure from a proposed P-O-P structural isomer; elemental composition alone cannot establish connectivity.","Distinguish free-acid material from a hypophosphate salt using counterion analysis and acid-equivalent balance.","Treat anhydrous acid, hydrated solid and aqueous solution as different sample states; do not transfer mass-based assay values or thermal constants between them without conversion and evidence."],"structure":{"bundles":[{"id":"identity-and-connectivity","name":"Identity and connectivity","description":"Establish which phosphorus oxoacid is present and resolve misleading labels.","layers":[{"id":"registered-identity","name":"Registered identity","description":"Connect the registry entry to a verified molecular identity.","findings":[{"id":"name-structure-agreement","name":"Name-structure agreement","description":"Require agreement between the supplied name, molecular formula and structural identifier.","questions":[{"text":"Does the supplied structure correspond to H4P2O6 with direct P-P connectivity?","id":"name-structure-agreement-q01","kind":"definition"},{"text":"Which inspected identity record supports the identifier, and does it describe the free acid or another form?","id":"name-structure-agreement-q02","kind":"provenance"}]}]},{"id":"neighbouring-oxoacids","name":"Neighbouring oxoacids","description":"Resolve confusion with other phosphorus acids and isomers.","findings":[{"id":"connectivity-discrimination","name":"Connectivity discrimination","description":"Require analytical evidence capable of distinguishing the intended structure from chemically different candidates.","questions":[{"text":"Which measurements distinguish this sample from hypophosphorous, phosphorous and phosphoric acids?","id":"connectivity-discrimination-q01","kind":"measurement"},{"text":"What evidence excludes an isomeric P-O-P structure rather than merely confirming the elemental formula?","id":"connectivity-discrimination-q02","kind":"boundary"}]}]}]},{"id":"sample-form-and-composition","name":"Sample form and composition","description":"Describe how much intact acid, water and accompanying material a sample contains.","layers":[{"id":"hydration-and-phase","name":"Hydration and phase","description":"Separate molecular identity from the physical form supplied.","findings":[{"id":"water-assignment","name":"Water assignment","description":"Distinguish established hydrate water from free moisture or solvent.","questions":[{"text":"Is the sample an anhydrous solid, a characterised hydrate or a solution at the recorded temperature?","id":"water-assignment-q01","kind":"definition"},{"text":"What water-content and phase measurements support that assignment?","id":"water-assignment-q02","kind":"measurement"}]}]},{"id":"assay-and-impurities","name":"Assay and impurities","description":"Resolve acid content from total phosphorus and non-acid constituents.","findings":[{"id":"species-specific-purity","name":"Species-specific purity","description":"Express purity on an explicit basis and account for other phosphorus species and counterions.","questions":[{"text":"Does the assay quantify intact hypophosphoric acid or only total phosphorus or titratable acidity?","id":"species-specific-purity-q01","kind":"measurement"},{"text":"Which phosphorus impurities and counterions were measured, and with what detection limits?","id":"species-specific-purity-q02","kind":"measurement"},{"text":"Is the reported percentage based on supplied material, dry material or anhydrous acid equivalents?","id":"species-specific-purity-q03","kind":"definition"}]}]}]},{"id":"acidity-and-hypophosphate-speciation","name":"Acidity and hypophosphate speciation","description":"Interpret acid-base measurements and relationships to hypophosphate ions and salts.","layers":[{"id":"solution-protonation","name":"Solution protonation","description":"Connect acidity to concentration, medium and measured equilibrium evidence.","findings":[{"id":"conditional-acidity","name":"Conditional acidity","description":"Treat protonation and dissociation constants as condition-dependent evidence requiring explicit sources.","questions":[{"text":"Which protonation states are supported at the measured pH, concentration and temperature?","id":"conditional-acidity-q01","kind":"measurement"},{"text":"What experimental source establishes the applicable dissociation constants and their ionic-strength conditions?","id":"conditional-acidity-q02","kind":"provenance"}]}]},{"id":"acid-salt-boundary","name":"Acid-salt boundary","description":"Track neutralisation without silently relabelling a salt as the free acid.","findings":[{"id":"neutralisation-accounting","name":"Neutralisation accounting","description":"Use counterion and acid-equivalent balances to distinguish solution speciation from a separately identified salt.","questions":[{"text":"What degree of neutralisation follows from the measured counterions and titration?","id":"neutralisation-accounting-q01","kind":"measurement"},{"text":"When does the supplied material require a linked hypophosphate-salt identity instead of the free-acid label?","id":"neutralisation-accounting-q02","kind":"boundary"},{"text":"What composition and equilibrium evidence is needed before planning a controlled neutralisation?","id":"neutralisation-accounting-q03","kind":"action"}]}]}]},{"id":"structural-integrity-and-transformations","name":"Structural integrity and transformations","description":"Determine whether the acid remains chemically identifiable through storage and treatment.","layers":[{"id":"storage-integrity","name":"Storage integrity","description":"Link sample history to repeated species-specific measurements.","findings":[{"id":"ageing-evidence","name":"Ageing evidence","description":"Assess integrity from observations rather than assigning an unsupported shelf life.","questions":[{"text":"How have temperature, water content, solution acidity and storage duration varied since characterisation?","id":"ageing-evidence-q01","kind":"provenance"},{"text":"Do repeat analyses show loss of intact acid or growth of other phosphorus species?","id":"ageing-evidence-q02","kind":"measurement"}]}]},{"id":"thermal-and-chemical-change","name":"Thermal and chemical change","description":"Distinguish phase changes from reactions that alter substance identity.","findings":[{"id":"transformation-assignment","name":"Transformation assignment","description":"Require product identification before labelling a thermal or chemical event as dehydration, hydrolysis, rearrangement or another reaction.","questions":[{"text":"Which products and remaining phosphorus species were identified after the observed change?","id":"transformation-assignment-q01","kind":"measurement"},{"text":"Does a reported thermal event represent melting, water loss or chemical decomposition for this particular form?","id":"transformation-assignment-q02","kind":"boundary"},{"text":"Which experimentally supported conditions define the permissible temperature and contact-time range for the intended operation?","id":"transformation-assignment-q03","kind":"action"}]}]}]},{"id":"handling-and-use-evidence","name":"Handling and use evidence","description":"Connect proposed operations to verified sample identity, applicable hazard information and analytical requirements.","layers":[{"id":"hazard-identity-match","name":"Hazard identity match","description":"Establish whether safety and regulatory records actually apply to this acid and sample.","findings":[{"id":"applicable-safety-record","name":"Applicable safety record","description":"Keep unverified hazard classifications and exposure limits explicitly unresolved.","questions":[{"text":"Does the safety document identify hypophosphoric acid by matching structure or verified identifier, rather than hypophosphorous acid?","id":"applicable-safety-record-q01","kind":"provenance"},{"text":"Which classifications, exposure limits and compatibility statements apply to the actual concentration, hydration state and jurisdiction?","id":"applicable-safety-record-q02","kind":"boundary"}]}]},{"id":"operation-suitability","name":"Operation suitability","description":"Translate measured sample quality into a decision about a specified use.","findings":[{"id":"evidence-before-use","name":"Evidence before use","description":"Define acceptance criteria for analysis, transfer, dissolution or neutralisation using the intended operation's needs.","questions":[{"text":"What maximum water, counterion and other-phosphorus-species contents can the proposed use tolerate?","id":"evidence-before-use-q01","kind":"action"},{"text":"Which missing identity, compatibility or stability evidence prevents a supported decision about that operation?","id":"evidence-before-use-q02","kind":"action"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-identifiers","name":"Identifiers and schemes","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these identifiers and schemes hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-identifiers-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these typical measurements hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of hypophosphoric acid this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Describe the structure and properties of hypophosphoric acid from chemistry references.","Report the hazard classification and storage needs from a safety data sheet."],"mustNot":["Handle or mix it outside a suitably equipped laboratory under qualified supervision.","Give instructions for making it outside a lawful teaching or research setting.","Dispose of it or its salts into drains or the environment.","Store it unlabelled or with incompatible materials."],"requiresHuman":["Any handling, transfer or disposal of the substance."]},"ethics":{"considerations":["Corrosive acids can injure people who handle them and those nearby.","Workers have a right to know the hazards of what they handle."],"affectedParties":["Laboratory workers","Students","Waste handlers"]},"owners":{"steward":"The laboratory or organization that holds it; chemical safety regulators set handling rules.","roles":[],"masterSystems":["Chemical substance inventories of national regulators"]},"relations":[{"target":"Q11173","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.hypophosphoric-acid","Wikidata: Q4492149 (https://www.wikidata.org/wiki/Q4492149)"]},"properties":{"applicability":"required","items":["Structural identity: H4P2O6 with direct P-P connectivity; confirmed, provisional or contradicted","External identity crosswalk: PubChem CID 24536; other identifiers require source and form verification","Material form: Anhydrous solid, specified hydrate, aqueous solution or unresolved form","Hypophosphoric acid assay: Mass fraction or mol/L, with analytical method and anhydrous-equivalent basis","Water content: Mass % water; mol H2O per mol acid where a hydrate is established","Solution acidity: pH with temperature, concentration and medium; titratable acidity in mol equivalents/L","Phosphorus species distribution: Mole fractions of identified phosphorus species, with detection limits and method","Counterion content: mmol/kg or charge equivalents per mol acid","Thermal event: °C with event assignment, pressure, heating rate and sample hydration","Sample integrity: Verified within specified conditions, changed, untested or indeterminate","Applicable hazard assessment: Source document, jurisdiction, revision date, concentration and material form"]},"recognition":{"applicability":"required","items":["Usually encountered as a labelled laboratory reagent or as its salts, not identifiable by sight alone.","Container label and safety data sheet identify it."]},"capabilities":{"applicability":"required","items":["Reconcile a labelled sample with the registered structural identity and flag name-based mismatches.","Select complementary analyses to distinguish intact hypophosphoric acid from salts, impurities and transformed phosphorus species.","Convert reported assay values between supplied-material and anhydrous-equivalent bases when water content is established.","Assess whether solution conditions support an intended acid-base measurement or neutralisation.","Compare storage and thermal history with measured sample integrity.","Determine whether available identity, composition and hazard evidence is sufficient for a proposed handling or use decision."]},"hazards":{"applicability":"required","items":["Corrosive to skin, eyes and airways.","Can react with incompatible substances."]},"interfaces":{"applicability":"required","items":["Globally Harmonized System of Classification and Labelling of Chemicals, United Nations."]},"context":{"applicability":"required","items":["Hypophosphoric acid is encountered mainly in specialized inorganic chemistry work involving phosphorus oxoacids and hypophosphate salts.","It is studied to understand phosphorus-phosphorus bonding and the chemistry of phosphorus in the +4 oxidation state."]}},"sources":[{"title":"Wikidata item Q4492149: hypophosphoric acid","url":"https://www.wikidata.org/wiki/Q4492149","note":"identity and sense of the item"},{"title":"Wikipedia: Hypophosphoric acid","url":"https://en.wikipedia.org/wiki/Hypophosphoric_acid","note":"general description of the item"}],"openQuestions":["Which authoritative CAS and EC records identify the free acid, and how do they distinguish hydrated forms and hypophosphate salts?","Which primary experimental studies establish the accessible solid forms and their melting, dehydration or decomposition events; is any reported boiling point experimentally meaningful?","What dissociation constants and validated speciation models apply across relevant temperatures, concentrations and ionic strengths?","Which analytical methods and reference data reliably distinguish intact hypophosphoric acid from its structural isomer and other phosphorus oxoacids, and what storage-dependent transformations do they demonstrate?","What substance-specific hazard classification, exposure-limit status and materials-compatibility evidence exists for characterised hypophosphoric acid samples?"],"resources":{"spec":"/models/things/publications/thing-q4492149/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q4492149/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T10:23:12Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-09T07:30:02+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}