Intensive, extensive, specific and molar properties
Scaling the system amount is different from changing its state.
Key knowledge
In the ordinary bulk thermodynamic model, extensive properties such as mass and volume scale with system amount at fixed state and composition. Intensive properties such as temperature and pressure do not scale that way. A specific property is expressed per mass; a molar property per amount of substance. Density can be intensive for a homogeneous material without being independent of temperature, pressure or composition.
Values and equations
v_specific = V/m; V_molar = V/n
- v_specific
- specific volume on the stated mass basis m^3 kg^-1
- V_molar
- molar volume on the stated amount/entity basis m^3 mol^-1
- V
- system volume m^3
- m
- system mass kg
- n
- amount of the specified entities mol
Conditions and scope
- Compare systems at the same intensive state and composition with compatible boundaries, not arbitrary unequal samples.
- Simple additivity neglects significant interface and inter-subsystem interaction contributions; it must not be imposed on every finite or long-range-interacting system.
- Positive mass/amount denominators and stated homogeneous state/composition.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- §1.4 Muddiest points: specific, extensive and intensive propertiesMIT Unified Engineering · Thermodynamics and PropulsionCourse notes
- Chemistry 2e (2019), §1.3 Physical and chemical propertiesPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapter
Evidence and review
Inspected MIT §1.4 MP1.1/MP1.2 definitions, additivity and V=mv, and Chemistry §1.3 intensive/extensive paragraphs. The model boundary excludes universal additivity; Chemistry's 'pot contains heat' wording is explicitly not adopted. Per-mole volume is the same stated normalization by amount.
2026-10-10 · Independent Mathematics and Information editor (/root/core_math_information). Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
Permanent link to this entry ↗- Record identity
- foundation-chem-intensive-extensive-properties
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions