Intensive and Extensive Properties
Intensive and extensive properties are the physical properties of matter where the chemical structure is unchanged. They are distinguished in that the intensive properties are independent of the amount of the substance, on the other hand, the extensive properties depend on the amount of material.
For example, density is an intensive property because it is the same value regardless of whether we are dealing with a liter of substance or a drop of the same substance. Also, the volume is an extensive property, since a liter and a drop are different quantities of the material.
intensive properties
It is basically a physical property that allows us to resemble a substance no matter how much substance we have. The main characteristic of intensive properties is that they have the same value in any part of the system that is measured.
For example, if we measure the temperature of water in a bottle or in a glass in the same room, it will be the same, even though they are different quantities.
Examples of intensive properties
- Density : is the amount of mass that is a given space. It is measured in kilograms per cubic meter kg/m 3 . For example, the density of iron is 7800 kg/m 3 .
- Temperature : is the measure of the internal energy of a body. It is measured in degrees Celsius (ºC), degrees Fahrenheit (ºF) or kelvin (K).
- Melting point : it is the temperature at which a substance in the solid state passes into the liquid state, and vice versa. For example, aluminum melts at 660ºC, whether it is 20 grams or 100 grams of the metal.
- Boiling point : it is the temperature at which a substance in the liquid state passes into the gaseous state. For example, alcohol evaporates at 78 ºC.
- Specific Gravity : is the ratio of the density of a material to the density of water. It is also called relative density, because it compares how dense something is relative to water. For example, the relative density of aluminum is 2.7.
- Conductance : is the property of materials to describe the ease of conducting electricity. It is measured in siemens (S).
- Resistivity : is the property of a material to resist the flow of electricity. It depends on the material, but not on its quantity. It is measured in ohm meters (Ω). For example, the resistivity of copper is lower (1.72 x 10 -8 Ω.m) than wood (10 8 Ω.m), so copper is a better conductor than wood.
- Thermal conductivity : is the property of a material to conduct heat. It is measured in watts per meter kelvin (W/mK). For example, the thermal conductivity of lead is lower than that of copper, which means that copper is a better conductor of heat.
- Viscosity : is a property of fluids that manifests itself as resistance to flow. It is measured in Newton seconds per square meter (Ns/m 2 . For example, glycerin has a higher viscosity than water, whether it is one liter of glycerin or one milliliter.
- Specific heat : is the amount of energy required to raise the temperature of one kilogram of a substance by 1 °C. It is measured as Joules per kilogram per degree Celsius, J/(kg °C). For example, the specific heat of water is 4186 J/(kg°C) and that of gold is 129 J/(kg°C).
extensive properties
It is a physical property that works to describe or distinguish a substance that depends on the amount of the material. The fundamental quality of an extensive property is that they are additive, meaning that the values of that property are added.
For example, mass is an extensive property, if we put together a 3 kg block of iron and a 2 kg block, the total mass is 5 kg.
Examples of extensive properties
- Mass : is the measure of the amount of matter that an object possesses. It is measured in kilograms (kg).
- Volume : is the measure of the amount of space that a body occupies. It is measured in liters (L).
- Length : is the measure of the dimension of an object. It is measured in meters.
- Number of molecules : is the number of molecules that make up a material.
- Heat capacity : is the amount of energy required to raise the temperature of a substance. It is measured in joules per kelvin (J/k). For example, if a kilogram of a material takes 1000 joules to raise its temperature by one kelvin, 2 kg of the same material will take twice as much energy.
- Thermal resistance : is a property of materials that opposes the flow of heat through two surfaces of a wall. For example, a concrete wall 10 centimeters wide has less thermal resistance than one 50 centimeters wide.
- Electrical resistance : is the electrical property of materials that prevents the flow of electrical charges. It is extensive because the resistance depends on the size and shape of the material, the greater the length of the material, the greater the resistance. It is measured in ohms (Ω).
- Electric charge : is the property that is related to the amount of electricity in a body, determined by the balance of positive protons and negative electrons. It is measured in coulombs (C).
- Entropy – is a property of the state of a thermodynamic system that depends on the amount of material. It is measured in joules per kelvin (J/K).
- Enthalpy : is a property of the state of a thermodynamic system that measures the amount of energy in a system, it is given in joules (J).
