sustancia

Sustancia is a term used in science to denote matter with a definite composition and characteristic properties. In chemistry and related disciplines, a sustancia can be a pure substance or a mixture. In everyday language, it often refers to a chemical substance, including drugs. Pure substances are classified as elements, which consist of a single type of atom, or compounds, which are formed from two or more elements in fixed proportions and bonded together.

Mixtures consist of two or more substances physically combined. They can be homogeneous, with a uniform composition, or heterogeneous, where components remain distinct. Unlike pure substances, mixtures do not have fixed composition or defined ratios, though their overall properties can be measured.

Properties of substance are described by intensive properties (such as density, boiling point, refractive index) and extensive properties (such as mass and volume). Substances undergo physical changes (phase transitions, dissolution) and chemical changes (rusting, combustion) that alter their composition.

Identification typically involves a name, a chemical formula, and sometimes a registry number such as a CAS number. The standard state of a substance at a given temperature and pressure is its most stable phase (solid, liquid, or gas).

In philosophy, substance refers to the underlying reality that supports properties. In practical contexts, sustancia is used in pharmacology to denote active ingredients or chemical substances in products and in regulatory frameworks for labeling and safety data.