Intensive and extensive properties are the physical properties of matter where the chemical structure remains unchanged. They differ in that the intensive properties are independent of the amount of the substance, while the extensive properties depend on the amount of material.
For example, density is an intensive property because it is the same independent value that we are dealing with a liter of substance or a drop of the same substance. On the other hand, volume is an extensive property, as one liter and one drop are different amounts of material.
An intensive property is a physical property that allows us to identify a substance no matter how much substance we possess. The main feature of intensive properties is that they have the same value to any part of the system that is measured.
For example, if we measure the temperature of the water in a bottle or glass in the same room it will be the same, even if they are different amounts.
Examples of intensive properties
- Density: is the amount of mass found in a given space. It is measured in kilograms per cubic meter kg / m3. For example, the density of iron is 7800 kg / m3.
- Temperature: is the measure of the internal energy of a body. It is measured in degrees Celsius, (ºC), degrees Fahrenheit (ºF) or kelvin (K).
- Fussion point: 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, be it 20 grams or 100 grams of metal.
- Boiling point: 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 known as relative density, because it compares how dense something is in relation 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 the quantity. It is measured in ohms meter (Ω). For example, the resistivity of copper is lower (1.72 x 10-8 Ω.m) than wood (108 Ω.m), which is why copper is a better conductor than wood.
- Thermal conductivity: is the property that a material has to conduct heat. It is measured in watts per kelvin (W / mK). For example, the thermal conductivity of lead is lower than that of copper, which means that copper is the best conductor of heat.
- Viscosity: is a property of fluids that manifests itself as resistance to flow. Newton is measured second per square meter (Ns / m2. For example, glycerin has a higher viscosity than water, be it a liter of glycerin or a milliliter.
- Specific heat: is the amount of energy needed 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).
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An extensive property is a physical property that serves us to describe or characterize a substance that depends on the amount of material. The main feature of an extensive property is that they are additives, that is, the values of that property are added together.
For example, mass is an extensive property; if we put together an iron block of 3 kg and another of 2 kg, the total mass is 5 kg.
Examples of extensive properties
- Too: is the measure of the amount of matter an object contains. It is measured in kilograms (kg).
- Volume: is the measure of the amount of space occupied by a body. It is measured in liters (L).
- Length: is the measure of the dimension of an object. It is measured in meters (m).
- Number of molecules: is the number of molecules that make up a material.
- Heat capacity: is the amount of energy needed to raise the temperature of a substance. It is measured in joules per kelvin (J / k). For example, if one kilogram of a material needs 1000 joules to raise the temperature to one kelvin, 2 kg of the same material would need 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 cm wide has less thermal resistance than one 50 cm wide.
- Electrical resistance: is the electrical property of materials that prevents the flow of electrical charges. It is extensive because the strength depends on the size and shape of the material, plus the length of the material plus strength. It is measured in ohms (Ω).
- Electric charge: is the property associated with the amount of electricity in a body, determined by the balance of positive protons and negative electrons. It is measured in coulomb (C).
- Entropy: is a state property of a thermodynamic system that depends on the amount of material. It is measured in joules per kelvin (J / K).
- Enthalpy: is a state property of a thermodynamic system that measures the amount of energy in a system. It is expressed in joules (J).
You may also be interested to see:
Canagaratna, SG (1992). Intensive and extensive: underused concepts. Journal of Chemical Education, 69: 957
Curtright, R., Ricketts, J. (1993). Specific gravity as intensive property: A laboratory study for the secondary school. Journal of Chemical Education, 70: 489. DOI: 10.1021 / ed070p489
Resnick, R., Halliday, D., Krane, KS (2002). Physics vol1. Homeland Publishing Group. Mexico.