mixture
(chemistry) a substance consisting of two or more substances mixed together (not in fixed proportions and not with chemical bonding)
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 agent to recognise a chemical mixture, assess its composition and condition, and determine appropriate handling, sampling, use and separation actions.
A mixture, in chemistry, is a material containing two or more chemical substances whose relative proportions are not constrained by a single chemical formula and whose coexistence does not itself constitute formation of a new compound.
It can be Identify and compare mixtures using constituent identities, composition ranges and grade requirements.; Plan representative sampling and select analyses that address unknown or variable fractions.; Assess whether a mixture requires homogenisation, controlled storage or rejection before use.; Evaluate dilution, blending or constituent adjustment against composition and compatibility constraints.; Select candidate separation methods and specify the evidence needed to establish recovery and purity.; Determine handling and use constraints from composition-specific measurements and applicable classification evidence..
Distinguishing features
The material contains at least two constituent substances; variation in particle size or physical state alone does not establish a mixture.
Its constituents are not required to occur in the fixed stoichiometric ratio defining a particular compound, although a formulation may specify precise proportions.
A visually uniform material can still be a mixture; appearance alone cannot distinguish a solution from a pure substance.
Intermolecular interactions do not by themselves make the material a single compound; chemical conversion must be distinguished from mixing.
The entry describes material composition and behaviour, independently of the product name, container or equipment used to make it.
Scope
+ Constituent identities, proportions, impurities and uncertainty in composition
+ Homogeneous and heterogeneous mixtures, including solutions, suspensions, emulsions and gas mixtures
+ Phase distribution, spatial uniformity and sampling representativeness
+ Measured mixture properties under stated temperature, pressure and test conditions
+ Mixing, separation, storage stability and changes in constituent identity
+ Composition-specific hazards, intended-use limits and applicable mixture classifications
- Pure substances and individual compounds as standalone chemical identities
- Products, packaging and commercial offerings that contain a mixture
- Mixers, separators and other processing equipment
- Complete manufacturing processes and reaction mechanisms
- Statistical mixture models and figurative uses of the word mixture
Characteristics
- Constituent identity
- Links to constituent substances, with identifier system, identity confidence and unresolved fractions Establishes what is mixed and which constituent information can support assessment.
- Composition
- Mass fraction, mole fraction, volume fraction or concentration with explicit basis, units, uncertainty and reference conditions Controls reproducibility, property interpretation and suitability for use.
- Formulation or grade
- Named specification, constituent ranges, impurity limits and acceptance criteria Distinguishes acceptable variation from contamination or an unsuitable batch.
- Phase constitution
- Number and physical states of phases, their fractions and constituent partitioning at stated conditions Determines whether a bulk composition describes the portion actually sampled or used.
- Homogeneity
- Spatial variation in selected constituent concentrations at a stated sampling scale and time Supports representative sampling and consistent dosing.
- Dispersed structure
- Particle or droplet size distribution in µm or nm, with morphology and measurement method where applicable Helps assess settling, dispersion stability, filtration and flow.
- Thermophysical behaviour
- Density in kg/m³, viscosity in Pa·s and phase-transition temperatures or ranges in K or °C, each with composition and test conditions Supports transfer, storage and separation decisions without assuming pure-substance constants.
- Storage stability
- Observed or assessed settling, creaming, phase separation, precipitation, evaporation or chemical change over a stated interval Indicates whether composition and performance remain suitable during storage.
- Separation behaviour
- Candidate physical methods linked to recoverable fractions, operating conditions, recovery and purity evidence Connects constituent and phase differences to feasible recovery or fractionation.
- Hazard and regulatory status
- Mixture classification, assessment basis, applicable jurisdiction, version and supporting evidence Supports handling decisions without treating constituent classifications as an automatic mixture classification.
Analytical facets
- substance
- material
- origin
- natural
- agency
- inert
- mobility
- varies
- scale
- not-applicable
- affordances
- observable
Also called
+68
Where this came from
oewn:2024 · CC BY 4.0
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 19 findings · 31 questions.
Constituents and composition Establishes which substances are present and how their amounts define the mixture.
Mixture identity depends on constituent composition and allowable variation rather than a single molecular formula.
Constituent resolution
Separates identified constituents from unresolved, incidental and specification-limited material.
Constituent accounting
Record constituent identities, their roles and the evidence supporting identification, preserving unknown fractions explicitly.
- Which substances are confirmed, suspected or unresolved, and what analysis or supplier evidence supports each identity? provenance
- Which constituents are intended ingredients, solvents, additives, impurities or contaminants under the applicable specification? definition
Composition and grade
Defines amount bases, allowable ranges and the relationship between nominal formulation and observed material.
Composition basis and tolerance
Record measured or declared composition with units, denominator, uncertainty and grade limits.
- Are amounts expressed by mass, volume or mole, and do they refer to the whole mixture, a dry basis or a particular phase? measurement
- What constituent ranges and impurity limits define the grade, and does the assessed batch meet them? boundary
- What portion of the total composition remains unaccounted for within measurement uncertainty? measurement
Phases and representative sampling Describes how constituents are distributed through phases and across the material being assessed.
A bulk composition can conceal concentration gradients, dispersed phases and portions with different properties.
Phase organisation
Characterises homogeneous and heterogeneous states under explicit observation conditions.
Phase and dispersion description
Record phases, constituent partitioning and any continuous or dispersed structure without relying solely on visual appearance.
- Which phases coexist at the stated temperature and pressure, and how are constituents distributed between them? measurement
- If a dispersed phase is present, what are its particle or droplet sizes and which phase is continuous? measurement
Sampling and uniformity
Connects sample location, preparation and timing to the mixture population represented.
Representative portion
Specify the scale of claimed uniformity and whether sample preparation changes the state being measured.
- At what spatial scale and elapsed time is the mixture sufficiently uniform for its intended use? boundary
- Which sampling locations, depths and preparation steps are needed to represent the bulk mixture or a deliberately selected phase? action
- Could agitation, filtration or transfer change the phase distribution or remove constituents before measurement? measurement
Properties and condition dependence Relates measured behaviour to composition, phase state and test conditions.
Mixture properties cannot generally be assigned from a constituent value or assumed to remain constant as composition changes.
Bulk property evidence
Captures properties relevant to the intended handling or use, with their measurement or estimation basis.
Qualified property values
Associate each relevant property with the tested formulation, method and conditions, distinguishing measurements from estimates.
- Which density, viscosity, conductivity, pH or other property measurements are relevant and meaningful for this mixture? measurement
- What composition, temperature, pressure and method apply to each value, and is it measured or estimated? provenance
Phase-change behaviour
Describes transitions and composition changes during heating, cooling or pressure changes.
Transition ranges and fractionation
Record observed transition points or ranges and whether changing phase also changes the composition of retained material.
- At what stated pressure and composition do boiling, freezing, clouding or precipitation occur, and are they points or ranges? measurement
- Does evaporation or another phase change preferentially remove constituents and alter the remaining mixture? boundary
Mixing, stability and separation Tracks how physical operations and elapsed time change mixture composition and organisation.
Agents need to distinguish reversible redistribution from constituent loss or chemical conversion before choosing corrective actions.
State evolution
Records changes during storage and use and the conditions under which the material remains suitable.
Physical and chemical change
Distinguish settling, phase separation and evaporation from reactions that alter constituent identities.
- Which physical or chemical changes occur over the intended storage interval, and under what conditions? measurement
- Can agitation restore an acceptable distribution, or has constituent loss or conversion changed the composition? action
Composition-changing operations
Evaluates blending, dilution and separation against target composition and recovery requirements.
Operation feasibility
Link candidate operations to relevant constituent differences, compatibility evidence and measurable acceptance criteria.
- What additions or removals would achieve the target composition, and what compatibility or phase-behaviour evidence is required first? action
- Which differences in volatility, solubility, size, density or affinity support a candidate separation, and what recovery and purity can be demonstrated? action
Mixture hazards and use constraints Connects actual composition and physical form to classification, exposure assessment and permitted uses.
A mixture needs its own assessment basis, including concentration effects, interactions and jurisdiction-specific treatment.
Classification and identity
Distinguishes mixture-level identifiers and assessments from records belonging only to constituents.
Applicable mixture record
Record identifiers, safety information and classification only for the composition and jurisdiction they actually cover.
- Does each CAS number, EC number or PubChem record identify the whole mixture, a constituent or a broader material category? boundary
- Which mixture classification applies in the relevant jurisdiction, and what testing, calculation or other accepted evidence supports it? provenance
Handling and use envelope
Connects concentration, physical form and exposure routes to evidence-supported handling and use limits.
Condition-specific action limits
Record constraints for the actual mixture and operation, including unresolved hazards that prevent a confident decision.
- Which exposure limits, material incompatibilities and storage constraints apply to this composition and physical form, and what is their documented scope? boundary
- What evidence is needed before heating, spraying, diluting or blending the mixture under the proposed conditions? 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 covers the chemical sense of mixture. 'No chemical bonding' is too absolute: constituents can exhibit intermolecular interactions, solvation and association without the material becoming a single compound.
- Mixtures have no universal melting point, boiling point, purity, hazard class or exposure limit; these require a specified composition and conditions.
- Identifier applicability and regulatory requirements need checking for the particular formulation and jurisdiction; the kinds listed overlap rather than forming an exclusive taxonomy.
- Which of these check these first hold for the sense of mixture this model covers, and on what evidence? provenance
Kinds and varieties
Recalled without web access and unsourced; every item is a lead to verify.
- Homogeneous mixtures, including solutions
- Heterogeneous mixtures
- Suspensions
- Colloidal dispersions
- Emulsions
- Gas mixtures
- Which of these kinds and varieties hold for the sense of mixture 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 - Two to seven digits, a hyphen, two digits, a hyphen, and one check digit - Constituents may have CAS numbers, and some defined mixtures have registry entries; there is no single CAS number identifying mixtures as a general category.
- Unique Formula Identifier (UFI) - 16 alphanumeric characters, commonly displayed in four groups of four - Used in the EU poison-centre notification framework to associate covered mixture formulations with submitted information; it is not a universal chemical identity.
- Which of these identifiers and schemes hold for the sense of mixture 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 (GHS)
- European Union Classification, Labelling and Packaging Regulation (CLP)
- European Union Registration, Evaluation, Authorisation and Restriction of Chemicals Regulation (REACH)
- United States Occupational Safety and Health Administration Hazard Communication Standard
- Which of these standards and regulation hold for the sense of mixture this model covers, and on what evidence? provenance
Real-world use
Recalled without web access and unsourced; every item is a lead to verify.
- Formulation of paints, coatings, adhesives and cleaning products
- Preparation of pharmaceutical formulations
- Blending fuels, lubricants and industrial gases
- Production of foods and beverages
- Preparation of laboratory solutions and analytical calibration mixtures
- Which of these real-world use hold for the sense of mixture this model covers, and on what evidence? provenance
Typical measurements
Recalled without web access and unsourced; every item is a lead to verify.
- Constituent mass fraction - 0-1 by definition; constituent fractions sum to 1 - kg/kg
- Constituent mole fraction - 0-1 by definition; constituent fractions sum to 1 - mol/mol
- Mass concentration - Mixture-specific; depends on constituent and conditions - g/L
- Density - Mixture-specific; composition, temperature and pressure must be stated - kg/m³
- Which of these typical measurements hold for the sense of mixture 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.
- Phase separation, sedimentation or creaming can make composition uneven.
- Evaporation or preferential loss of a constituent can change concentration and performance.
- Incompatible constituents can react, releasing heat, gas or hazardous products.
- Flammability, toxicity and corrosivity depend on composition and cannot always be inferred by averaging constituent properties.
- Contamination or blending errors can place composition outside its specified limits.
- Which of these failure modes and hazards hold for the sense of mixture this model covers, and on what evidence? provenance
Regional variation
Recalled without web access and unsourced; every item is a lead to verify.
- Chemical hazard classification and labelling requirements differ between jurisdictions implementing GHS.
- The EU uses CLP and REACH frameworks, while US workplace hazard communication is governed by OSHA requirements.
- Poison-centre notification and formulation identification requirements vary by jurisdiction.
- Which of these regional variation hold for the sense of mixture 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.
- Pure substance - A pure substance has a single chemical identity; a mixture contains multiple constituent substances.
- Chemical compound - A compound has chemically combined elements defining a chemical substance; mixing constituent substances does not itself create that identity.
- Solution - A solution is a homogeneous mixture; mixtures also include heterogeneous materials.
- Alloy - An alloy is a material with metallic character containing multiple elements; its phases may include solid solutions and intermetallic compounds.
- Formulated product - A formulated product is specified for an intended use and may contain a mixture; mixture describes composition rather than commercial purpose.
- Mixing - Mixing is a process; a mixture is the resulting or existing material.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of mixture this model covers, and on what evidence? provenance
What the second pass must settle
- Does the other registry entry named mixture represent the same chemical sense, and does an existing world model already provide the authoritative publication?
- How should this registry distinguish mixtures from variable-composition substances, solid solutions and materials whose constituent identities are only partly resolved?
- What evidence thresholds and sampling scales should support claims of homogeneity and composition completeness for different mixture classes?
- How should reacting mixtures track changing constituents while remaining linked to neighbouring reaction and process models?
- Which authoritative identifier and classification sources cover the intended jurisdictions, and how should formulations without a mixture-level identifier be represented?