Is Mass An Extensive Property: How, Why And Detailed Facts

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This article answers the question is mass an extensive property? Our discussion shall start with the true meaning of mass and the definition of extensive properties.

There are two types of properties- Extensive properties and intensive properties. We shall discuss about both these properties and then carry our discussion further to answer the question is mass is an extensive property? Let us find the answer in this article.

What is mass?

Mass is the measure of matter in a substance. Mass represents the amount of matter present inside the system. It tells us about the quantity of matter present inside the system.

The unit of mass is Kilogram, gram etc. When mass comes under the influence of gravity, it becomes weight. That means, one can feel how heavy an object is. Greater the mass, greater will be the weight of object.

is mass an extensive property
Image: Measurement of mass is done by using weights of standard measurements

Image credits: Coyau / Wikimedia Commons / CC BY-SA 3.0, Poids fonte 2 kg 03, CC BY-SA 3.0

What is an extensive property?

Extensive properties are those properties of physical quantities whose value depends on mass. If the value of mass changes then the value of extensive properties will also change.

The extensive properties are directly affected by the amount of matter present in the system. We can say that extensive properties are directly proportional to the mass of that particular physical property. We shall study more about extensive properties in this article.

Examples of extensive property

The following list includes the examples of extensive properties.

  • Amount of substance– Amount of substance can be given by the number of parts of that particular substance present inside the system. This can be considered analogous to mass which simply means the total amount of matter present in the system.
  • Enthalpy– Enthalpy is the energy of the system whose value is given by adding the internal energy and product of pressure and volume of the system. The enthalpy is a mass dependent property. More the mass, more will be the enthalpy. The enthalpy term can be made intensive if we divide the enthalpy by total mass. We can note that an extensive property can be converted to intensive property by dividing by mass.
  • Entropy– The amount of randomness or disorderness in a system is called as the entropy. It is a very important term used in the field of thermodynamics and has many applications in the same field.
  • Gibbs Energy– Gibbs energy is the total non expansion work that we can attain from a system. The system has to be thermodynamically closed system.
  • Heat energy– Heat is the result of kinetic energies of the molecules in the system. The transfer of heat takes place in the form of transfer of energies between these molecules. The most important factor responsible for heat transfer to take place is the difference in temperatures of the two systems.
  • Internal energy– Internal energy of the system can be defined as the intrinsic energy stored inside the system. It is given by the letter U. Internal energy depends on the mass of the system, meaning greater the mass greater will be the value of internal energy.
  • Spring stiffness– The spring stiffness is given by k. It is the limit up to which a spring can be compressed or stretched.

What is an intensive property?

Intensive properties are those properties of physical quantities whose values are independent of mass.

These properties don’t depend on the mass present in the system. These properties have no effect of mass on them. Some notable examples of intensive properties are discussed in later sections of this article.

Examples of intensive property

As discussed in above section, the properties whose value is independent of mass are called as intensive properties. The examples of intensive properties are given below-

  • Specific enthalpy– When we divide the value of enthalpy with mass, we get specific enthalpy. Specific properties are those properties which we get after dividing extensive properties by mass.
  • Specific entropy– Specific entropy like specific enthalpy, is the value of entropy we get after dividing by mass.
  • Density– Density is a very commonly used term which we all know. It is the amount of mass present in a certain amount of volume. Volume and mass both are extensive properties hence their ratio will give out an intensive property.
  • Temperature– Temperature is an intensive property as its value does not depend on mass in any manner. Even if we divide the systems in to two parts, their temperatures will still remain the same.
  • Pressure– Like temperature, the value of pressure also does not changes if the value of mass changes. The value of pressure remains unaltered hence it also comes under intensive property.

How is mass an extensive property?

Now we know the definition of both mass and extensive property. Now we also know that extensive properties are majorly affected by the amount of matter present inside the system or in simple terms mass of the system. 

The definition of mass says that it is the amount of matter a system contains. If we divide a system into two equal halves, then the mass of the individual systems will also get divided into two equal parts. Hence we can say that mass is an extensive property.

Is change in mass an extensive property?

Yes. The value we get after the difference in two masses depends on the individual masses. Meaning the value of change in mass will be altered if the masses of individual systems are changed.

Since the value of change in mass depends on the individual value of masses, we can say that the change in mass is also an extensive property.

How is change in mass an extensive property?

We may think that change in mass is an intensive property as it is merely a difference between two masses. But this is not the actual case. The difference between two extensive properties is also an extensive property.

But if we look closely, the value of difference depends on the individual masses. Also the properties whose value is directly affected by mass is called as an extensive property. Hence we can say that change in mass is also an extensive property.

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