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In science, matter is understood as anything that has mass and that occupies a place in space. Matter can occur in many different forms in the universe and each of these forms is characterized by a set of properties.
The properties of matter are then defined as all those characteristics of a body or substance provided with mass that we can measure in some way or observe under a certain set of conditions. This is quite a broad concept involving a large number of different properties, which makes it necessary to divide or classify them in some way.
The simplest way to divide or classify the properties of matter is based on their dependence on the size or extension of the body or substance to which they refer. In this sense, the properties can be divided into:
- extensive properties
- intensive properties
Next, we will see what each of these types of properties are, as well as some examples of them.
extensive properties
There is a set of properties of matter that varies depending on the size or extension of the body to which it refers; that is, its properties depend on the amount of matter present. These properties are called extensive properties.
There are a large number of extensive properties of matter. Some are physical properties, others are chemical; some are vector quantities, while others are scalar quantities. Regardless of this, however, we recognize them because they generally increase as the size or amount of matter present increases.
Examples of extensive properties
Here is a list of the most common extensive properties, as well as some examples of extensive properties applied to thermodynamics:
Mass (m)
Mass is an extensive property that directly measures the amount of matter present in a body . In physics, it is defined as a measure of a body’s inertia, that is, the tendency to resist a change in motion.
As a property of matter, mass is often represented by the lowercase letter m. In the International System of Units (SI), mass is measured in kg, but there are many other units of mass including the gram with all its multiples and submultiples, pounds and their multiples, etc.
Mass is an intensive property, since the larger the size of a system, the greater its mass.
The volume
Volume is understood as the amount of space that a body occupies. This property gives us an idea of the size of the bodies and, as expected, the larger the system, the greater its volume.
Volume is measured, in the SI, in units of cubic meters (m 3 ). In addition to these units, volume can be expressed in terms of any cubed unit of length.
Weight
Often confused with mass and closely related to it, weight is nothing more than the force with which the planet earth attracts objects towards its center. By Newton’s second law, weight is directly proportional to mass and therefore to the amount of matter, so it is an extensive property. Also, being a force, weight is also a vector property, although in most cases only its numerical value is used.
Unlike mass, the units of weight are units of force such as the Newton (Nw), the dyne (dyn), and the kilogram-force, among others.
The heat
Heat is the amount of thermal energy that must be supplied to a system to increase its temperature, or the amount of thermal energy that must be released to cool down. This amount obviously depends on the amount of matter, so it is an extensive property.
For example, it is not the same to heat 200 g of water present in a glass as it is to heat 5 l.
absorbance
Absorbance is a measure of the amount of light of a certain wavelength (understood as color) that a sample of a substance or a mixture of substances can absorb. It is an extensive quantity or property, since the greater the amount of matter that light must pass through, the greater the amount of light absorbed, that is, the greater its absorbance.
Electric resistance
Electrical resistance is a physical property that measures the opposition offered by a material to the flow of electrical current through it. This property has a particular relationship with the extension of the system, since it increases as the length of a conductor increases, but decreases as the cross-sectional area of the conductor increases.
In any case, since it depends on the dimensions or extension of the system, it is an extensive property.
electrical conductance
Electrical conductance is the inverse property of resistance. This measures the ease with which a material can conduct electricity and is related to the length of the conductor in the opposite way to resistance, increasing with the cross-sectional area of the conductor, but decreasing with the length of the conductor.
intensive properties
Intensive properties are the opposite of extensive ones. That is, they are those properties that do not depend on the amount of matter, but only on its composition. These properties are very useful for characterizing the material an object is made of.
Intensive properties derived from extensive properties
Many of the intensive properties come from some extensive property that is normalized by dividing by the amount of matter (by mass or moles, for example), while others are intensive properties in their own right and do not derive from any extensive property.
Those intensive properties that are calculated as an extensive property divided by the mass are usually named in the same way as the extensive property by adding the word “specific” or “specific” at the end. Thus, the intensive property calculated as the volume divided by the mass is called the specific volume, the heat divided by the mass is called the specific heat, and so on.
On the other hand, some extensive properties can be transformed into intensive properties by dividing them by the number of moles. In these cases, extensive properties are transformed into molar quantities, such as molar volume, molar heat capacity, molar enthalpy of reaction, etc.
Examples of intensive properties
Temperature
Temperature is a measure of the thermal agitation of the atoms and molecules that make up matter. This is an intensive property, since if a body is in thermal equilibrium, its temperature will be the same at any point regardless of the size of the system.
For example, if a pool filled with water is at a temperature of 20 °C and we extract a full glass of this water, the temperature of the water in the glass will be the same as in the entire pool, despite being made up of a much smaller amount of matter.
The pressure
Pressure is defined as the force exerted on the surface of a body per unit area.
This is an intensive property, since when a body is subjected to the pressure of, for example, the atmosphere or another fluid, the pressure is the same at any point on its surface and it does not change if we increase the size of the body. or we modify its surface area.
Pressure can be measured in different units such as pascal (Pa, which is the unit in the metric system), atmospheres, psi (pounds per square inch, the unit in the imperial or English system), millimeters of mercury (mmHg) , meters of water (m H 2 0), etc.
The density
Density measures the amount of mass of a substance that is per unit volume. It is a typical example of an intensive property that is characteristic of each material. On many occasions, this property serves to distinguish one substance from another. For example, in ancient times it was used to distinguish precious metals from cheap imitations or to detect pieces that weren’t solid. Density is expressed in units of mass over volume such as g/mL, g/L, kg/m 3 , etc.
electrical conductivity
It is the intensive version of conductance. However, while the latter measures how well a conductor of certain dimensions conducts electricity, conductivity measures how well a material conducts electricity, regardless of its shape or dimensions.
electrical resistivity
The same thing that happens with conductivity and conductance, happens with resistivity and resistance. Resistivity measures how much a material opposes the conduction of electrical current through it.
The color, the smell and the taste
These three are qualitative properties based on our senses. Color is an intensive property, since the color of a substance does not depend on the amount of it. For example, milk is white, regardless of whether we have 1 milliliter or a gallon. We cannot say that milk is more or less white because we have more or less milk. Something similar happens with taste and smell. For example, seawater tastes the same salty no matter how much seawater we taste.
Concentration
Concentration is an intensive property that characterizes solutions, since it represents the proportion in which their components are mixed, regardless of the total amount of solution present.
molar volume
It corresponds to the volume divided by the number of moles and represents the volume that a mole of substance occupies in a set of given conditions.
molar absorptivity
It corresponds to the intensive form of absorbance. It refers to the unit of absorbance per unit of concentration per unit of optical pathlength of light. In other words, it is the absorbance that a solution of unit concentration contained in an optical cell of unit length would have.
References
Álvarez, DO (2021, September 30). Intensive and Extensive Properties . Examples. https://www.ejemplos.co/20-ejemplos-de-propiedades-intensivas-y-extensivas/
Chang, R., Manzo, Á. R., Lopez, PS, & Herranz, ZR (2020). Chemistry (10th ed .). McGraw-Hill Education.
Padial, J. (2017, October 30). What are the intensive and extensive properties of matter? curious. https://curiosoando.com/propiedades-intensive-y-extensivas-de-la-materia
Intensive and extensive properties . (2021, June 2). Differentiator. https://www.diferenciador.com/propiedades-intensivas-y-extensivas/
Intensive and Extensive Properties of matter . (2014, February 23). Chemistry and something else. https://quimicayalgomas.com/quimica-general/propiedades-intensivas-y-extensivas-de-la-materia/
