Intensive and extensive properties of matter: what are they and what are they - Meanings
Posted on 10-02-2022
What are the intensive and extensive properties of matter?
The intensive and extensive properties of matter are those characteristics that describe it, such as mass, volume, density, or temperature.
Intensive properties are those that will remain unchanged even if the amount of matter varies. While extensive properties vary depending on the amount of matter in a body.
Let us remember that matter is everything that surrounds us and that occupies space, such as oxygen, water, rocks, living beings, etc.
Intensive properties of matter
Intensive properties of matter are defined as those that do not depend on the amount of material in a body.
This means that they will remain the same even if the amount of matter in a body varies. That is to say, that the mass or the volume can vary, and that property is not going to be altered.
Among the intensive properties, the following stand out.
Density
It is the relationship between the mass of a body and the volume it occupies. In other words, it is the amount of matter that a body possesses, expressed in units of mass (kg or gr) and volume (m 3 or cm 3 ). Therefore, its unit of measurement is kg/m 3 or gr/cm 3.
The density of a body will always be the same regardless of its mass, which is why it is an intensive property.
An example would be the density of iron, which is 7.874 g/cm 3. That means iron has 7.874 grams of matter per cubic centimeter, no matter how much iron we're measuring.
Temperature
Temperature is a magnitude that expresses the amount of kinetic energy of a body. It is measured in degrees Celsius or Centigrade. (°C).
Temperature is an intensive property because it will not vary even if the amount of matter varies.
An everyday example is that if we boil water, the temperature will be the same (100 °C) whether it is one liter or 50 liters of water.
Surface tension
It is the ability of bodies in a liquid state not to increase their surface. This is achieved because they manage to resist the forces that are applied to them and the molecules that make them up stay together. This capacity does not vary even if the amount of matter changes, so it is an intensive property.
For example, when we use a dropper, the surface tension is what makes the liquid fall as a drop and not as a jet, because the tension makes the molecules that make up the drop stay together.
Elasticity
Elasticity is a magnitude that measures the deformation capacity of a body once a force has been applied to it. No matter the size of the body or its amount of matter, its elasticity will always be the same and that is why it is an intensive property.
For example, an elastic band for exercise will have the same elasticity if we use it fully or if we cut it in half.
melting temperature
It is the temperature at which a body in solid-state changes into a liquid state. It is measured in degrees centigrade (°C).
It is an intensive property because the melting temperature does not vary even if the amount of said element varies. It is worth noting that each material has its own melting temperature.
For example, the melting temperature of the water is 0 °C. If we have a kilo of ice or a ton of ice, we will need to bring that amount of material to 0 degrees Celsius so that it can pass into the liquid state.
Boiling temperature
It is the temperature at which a body changes from a liquid state to a gaseous state. It is measured in degrees centigrade (°C).
The boiling temperature is a magnitude that does not change, regardless of the amount of matter in the body. And just like the melting temperature, each material boils at a specific temperature.
For example, the boiling temperature of the water is 100°C, it doesn't matter if we boil a cup of water or 50 liters.
Resistivity
Resistivity is the magnitude that measures the ability of a body to resist the flow of electric current. It is measured in ohm meter (ohm m).
The measure of resistivity of a material is always the same although its quantity varies, that is why it is an intensive property.
For example, the resistivity of aluminum will always be 8.90 x 10-8 ohm m, even if the quantity is one gram or one kilo.
Thermal conductivity
It is a magnitude that measures the capacity of a body to transfer heat to another body or to its surroundings. It is measured in Watts over Kelvin per meter (W/km).
It is an intensive property because the amount of material in a body can vary, but its conductivity will be the same.
For example, the thermal conductivity of a diamond is 2300 W/km, whether it is a small diamond or a large one.
Specific heat
It is the measure that expresses the amount of heat that a body needs to increase its temperature by one degree. It is measured in Joules over kilograms per Kelvin (J/kg.K) or in calories per gram degree centigrade (cal/gr.C).
The same amount of specific heat is needed for a body, even though its mass varies. Therefore it is an intensive property.
For example, the specific heat of gold is 0.0308 cal.gr.°C. This applies to one gold coin or one ton.
specific volume
It refers to the volume occupied by a unit mass of a body. That is, it is the spatial measurement of a body in a gram or a kilogram. It is measured in cubic meters over kg (m 3 /kg) or cubic centimeter over grams (cm 3 /g).
The amount of matter does not influence the specific volume of a body and for this reason, it is an intensive property.
For example, the specific volume of water will always be 0.001 m 3 /kg regardless of its quantity.
Viscosity
It is the property of bodies to resist fluidity. Therefore, when we observe that a certain fluid is thick, what we are seeing is an expression of its viscosity. This property does not change even if the amount of matter varies, so it is an intensive property.
The unit of measurement for viscosity is newton-seconds per square meter (Ns/m 2 ).
An example of viscosity is motor oil, whose viscosity is 0.03 (Ns)/m 2 at a temperature of 20°C, no matter if it is one liter of oil or 5 liters.
Extensive properties of matter
Extensive properties of matter are defined as those that depend on the amount of material in a body.
The greater the mass or the larger the body or system, the greater the proportion of that property. This means that extensive properties are not fixed, they vary according to the amount of matter.
Also, extensive properties are additive, meaning they can be added together. For example, if another liter of the same liquid is added to one liter of water, it will be two liters of water. In this case, the volume of the water was added or summed.
These are the most important extensive properties of matter.
Mass
Mass is the magnitude that expresses the amount of matter that a body has. Its unit of measure is the kilogram (kg.).
Mass is determined, among other factors, by the number of molecules in a body. The more molecules, the more mass the body will have.
An example to illustrate mass as an extensive property is that if we take a 5-kilogram sandbag and remove half of the contents, the mass of the bag will have decreased.
Electric resistance
It is the property of bodies to prevent the flow of current in an electrical circuit and its unit of measurement is the ohm (Ohm). The electrical resistance will vary depending on the amount of material, so it is an extensive property. In this, it differs from electrical resistivity, which is an intensive property that depends on the type of material, not its quantity.
For example, the electrical resistance of a meter of cable is different from the resistance of a cable of 10 meters.
electrical charge
Electric charge is the property of systems to attract or repel other bodies. The unit of measure for the charge is the Coulomb ( C ). This is an extensive property because it depends on the amount of mass of the body.
For example, a particle with two positive charges has more influence on its environment than the same particle with only one positive charge.
Volume
Volume is the spatial measure of a three-dimensional body. It's unit of measurement according to the International System of Units is the cubic meter (m 3 ) and in the decimal system, it is the liter, which is equivalent to 0.001 m 3, one-thousandth of a cubic meter.
The variation in the amount of matter implies a change in the volume of the body, so it is an extensive property.
For example, if we have 100 cubic meters of water in a pool and we take out 25 cubic meters, now the volume is 75 cubic meters.
Heat capacity
It refers to the amount of heat a body needs to change its temperature. Its unit of measurement is joules per kelvin J/K.
The greater the amount of matter, the more heat is required, so the heat capacity varies.
An example is that we need more heat capacity to heat a pot of soup than we do to heat a cup of soup.
Length
Length is a magnitude or measure of distance. Its unit of measure is the meter (m).
A variation in the amount of mass implies an increase or decrease in length, for this reason, it is an extensive property.
For example, if a wooden rod is three meters long and we cut a section of 30 centimeters, now the length of the rod is 2.70 m.
number of molecules
Each body has a certain number of molecules depending on its mass. The greater the mass, the greater the number of molecules. This variation is what makes it an extensive property.
For example, in a kilo of flour, there are more molecules than in half a kilo.
entropy
Entropy is the degree of disorder of a system. Its measurement system is joules per kelvin (J/K). The larger the system, the greater the entropy. This makes it an extensive property since the size of the system influences its degree of disorder.
For example, in the ocean, the degree of entropy is greater than in a hive of bees.
enthalpy
It is the amount of energy that a system exchanges with its surroundings, either because it gives up an energy or because it takes it. Its unit of measurement is joules (J). The number of joules varies depending on whether the body releases or absorbs energy, so it is an extensive property.
For example, if we put a cup of laundry detergent in a gallon of water, more heat is released than if we put a tablespoon of the same detergent.
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