Bulk Property
Bulk properties are characteristics of a system that remain constant regardless of the system's size or the amount of material present. Often referred to as intensive properties, these attributes do not change when the system is divided or altered. For example, while weight and juice content of an orange are dependent on its size (extensive properties), its color, taste, and fragrance are bulk properties that remain the same regardless of how much of the orange is present. This distinction is significant because it helps to understand how different properties behave when the system undergoes changes, such as dividing or combining materials.
Common examples of bulk properties include chemical potential, color, ductility, and viscosity, among others. Some properties, like density, are derived as a ratio of extensive properties (mass per unit volume) and are inherently intensive. Understanding bulk properties is crucial in various scientific and engineering disciplines, as they help define the intrinsic qualities of materials and systems without being influenced by their scale.
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Subject Terms
Bulk Property
A bulk property is a physical property of a system that is "scale-invariant", that is, it does not change with the scale, size, or total amount of material in the system. Bulk properties are also called intensive properties, intensive variables, and intensive quantities; different terminology is favored by different disciplines. A property in the sense used in mathematics (and philosophy) is an attribute possessed by an object. While the weight or juice content of an orange, for instance, is scale-variant, its color, taste, and fragrance are bulk properties, properties that do not affect and are not affected by scale.
In contrast with bulk or intensive properties, extensive properties are those that are proportional to the material in the system, such as mass or volume. Common extensive properties include mass and volume, as well as other measures of size, momentum, electrical charge, and magnetic moment. Extensive properties are always measurable, and can be represented as the sum of subsystems within the system. The distinction is important because it indicates what aspects of a system will change or remain constant when material changes are enacted. Further, the distinction is not always as obvious as it seems: Ratios between extensive properties are not themselves extensive. Density, for instance, is the ratio of mass to volume. Given a constant gravity, density is thus an intensive property.
Overview
Manuel de Landa explained bulk properties as those which cannot be metrically divided, giving the example of a liter of 90 degree water. While the water can be divided into two half-liter quantities—a liter being a measure of volume, and volume being an extensive property—it cannot similarly be divided into two containers of 45 degree water, nor into any other configuration of hot and cold units of water. This is true even though the liter container may have been filled with alternating units of hot and cold water. Likewise, though the water may have been dyed purple with drops of red dye and drops of blue dye, it cannot now be divided into red and blue, or purple and colorless; its purpleness is a bulk property.
Common bulk properties include chemical potential, color, concentration (the amount of sugar in any quantity of the same soda remains the same percentage, or concentration), ductility, elasticity, electrical resistivity, flammability, hardness, magnetization and magnetic field, malleability, molar absorptivity, pressure, specific energy, specific gravity, specific heat capacity, and viscosity. Not all of these properties are relevant to all systems; viscosity, for instance, is not a relevant consideration at the micro scale. Some bulk properties are simply extensive properties per unit volume, in the way that density is mass per unit volume. There are also many, many more bulk properties specific to certain objects, such as the aforementioned fragrance of the orange, or the wetness of liquid.
Bibliography
Dobrushkin, Vladimir. Applied Differential Equations. New York: CRC, 2014.
Foucault, Michel. The Archaeology of Knowledge. New York: Routledge, 2012.
Gillespie, Sam. The Mathematics of Novelty. New York: RePress, 2008.
Herrera, Ismael, and George F. Pinder. Mathematical Modeling in Science and Engineering. New York: Wiley, 2012.
Shapiro, Stewart. Thinking About Mathematics: The Philosophy of Mathematics. New York: Oxford UP, 2013.
Stuwe, Kurt. Geodynamics of the Lithosphere. New York: Springer, 2014.