Intensive and extensive properties Totally Explained

Everything about Intensive Property totally explained

In the physical sciences, an intensive property (also called a bulk property), is a physical property of a system that does not depend on the system size or the amount of material in the system. (see: examples)By contrast, an extensive property of a system does depend on the system size or the amount of material in the system. (see: examples) Some intensive properties, such as viscosity, are empirical macroscopic quantities and are not relevant to extremely small systems.

Intensive quantity

An intensive quantity (also intensive variable) is a physical quantity whose value does not depend on the amount of the substance for which it's measured. It is the counterpart of an extensive quantity. For instance, the mass of an object isn't an intensive quantity, because it depends on the amount of that substance being measured. Density, on the other hand, is a bulk property of the substance. The riddle "what weighs more, a pound of feathers or a pound of lead?" is an example where it's easy to confuse the intensive and extensive quantities.

Combined intensive quantities

At least two functions are needed to describe any thermodynamic system, an intensive one and an extensive one.
If a set of parameters,

\right),

where the partial derivative is taken with all parameters constant except

A_j

. The converse is also true - any function which obeys the above relationship will be extensive.

Examples

Examples of extensive properties include:

mass

length

volume

entropy

enthalpy

energy

electrical resistance

texture

heat

Distinction from perceptions

Certain perceptions are often described (or even "measured") as if they're intensive or extensive physical properties, but in fact perceptions are fundamentally different from physical properties. For example, the colour of a solution isn't a physical property. A solution of potassium permanganate may appear pink, various shades of purple, or black, depending upon the concentration of the solution and the length of the optical path through it. The colour of a given sample as perceived by an observer (ie, the degree of 'pinkness' or 'purpleness') can't be measured, only ranked in comparison with other coloured solutions by a panel of observers. Attempts to quantify a perception always involve an observer response, and biological variability is an intrinsic part of the process for many perceived properties. A given volume of permanganate solution of a given concentration has physical properties related to the colour: the optical absorption spectrum is an extensive property, and the positions of the absorption maxima (which are relatively independent of concentration) are intensive properties. A given absorption spectrum, for a certain observer, will always be perceived as the same colour; but there may be several different absorption spectra which are perceived as the same colour: there's no precise one-to-one correspondence between absorption spectrum and colour even for the same observer.
The confusion between perception and physical properties is increased by the existence of numeric scales for many perceived qualities. However, this isn't 'measurement' in the same sense as in physics and chemistry. A numerical value for a perception is, directly or indirectly, the expected response of a group of observers when perceiving the specified physical event.
Examples of perceptions related to an intensive physical property:

Temperature: in this case all observers will agree which is the hotter of two objects.

Loudness of sound; the related physical property is sound pressure level. Observers may disagree about the relative loudness of sounds with different acoustic spectra.

Hue of a solution; the related physical property is the position of the spectral absorption maximum (or maxima). Examples of perceptions related to an extensive physical property:

Color of a solution: The related physical property is the transmission or absorption spectrumFurther Information

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