Why is Density an Intensive Property | A Detail Guide with Examples

Density, a measure of how tightly matter is packed within a substance, is an intensive property that remains constant regardless of the sample size. 

This intrinsic characteristic of density makes it a fundamental measure in various fields, allowing scientists and engineers to identify and compare substances efficiently. 

As we delve into the concept of density, we’ll explore its significance and understand why it’s considered an intensive property. This exploration will shed light on its crucial role in both everyday applications and complex scientific endeavors.

What is meant by Density?

So to properly understand what density being an intensive property means in the world, we must first fully grasp what density is and what it entails. So the word density comes from the early 17th century: from French densité or Latin densitas, from census’ dense.

‘In modern times, this word is used across all fields of knowledge and science regarding the degree of compactness of a substance. Its more scientific definition can also be described as ‘the quantity of mass per unit volume of a substance.

‘In physics, density is calculated as kilogram per meter cube, equal to mass over volume, where mass is measured in kilograms and volume is measured in meter cube.

D = m/v

This last definition is the one most commonly used in physics. The concept of density is also applicable in computer sciences and can be described as a measure of the amount of information on a storage medium.’ The term density is also very relevant and applicable in other daily life dealings related to population and city infrastructure.

Density can also be defined as ‘the number of people or things in a given area or space.’ In short, it measures how close things are packed together.

Density makes you understand how two cubes of the same size and dimensions but made up of different materials are not the same. For example, if you take a large cube of Styrofoam and a very small cube of lead, they can have the same density.

One of the most famous or widely used applications of density is determining her mass will float on water; for example, Ships and submarines represent both conditions of floating and sinking, respectively. The ship floats on water because it has less density.

But how this less density is achieved? Ships have ballast tanks that hold air. The air has little mass but a large volume, which reduces its density and causes it to float compared to submarines that empty their ballast tanks. 

Examples of Density

Iron, lead, and platinum is the most common examples of dense materials. Some metals and rock also come under this category of dense materials. Dense materials generally feel heavy or hard. At the same time, sparse materials are less dense or opposite of dense. They include bamboo, Styrofoam, or aluminum.

When comparing solids, liquids, and gases, we see that their density depends upon the behavior of their particles. As we know, solids have densely packed particles. In liquids, particles can slide over one another, while the gases have particles spaced apart and have random motion. Thus solids are the densest and then come to the liquids and gases.

What is meant by Intensive Properties?

Now, as we have cleared our minds about the concept of density, we must learn what intensive properties are before moving forward. The physical properties of substances and systems are divided or categorized into whether they change or depend upon size or amount of substance or independent of it.

In simple words, if a property doesn’t change when the amount or size of material changes but depends upon the material of the substance, it is an intensive property, like density. If it shows changes with these conditions, then it is an extensive property like mass or volume, etc.

Examples of Intensive Properties:

Temperatures, density, color, melting and boiling point, etc., all are intensive properties as they will not change with a change in size or quantity of matter. The most commonly known and understood intensive properties studied in science are boiling point, density, state of matter, color, melting point, odor, temperature, and refractive index.

So it doesn’t matter if the substance is 5 g or 5 kg; they could have the same density, or one’s density could be much higher than the other. It just doesn’t depend on the amount of the substance under consideration.

It must also be considered that volume is not an intensive property as it depends on the amount of the substance under question. More quantity of any substance will have a higher volume than a lesser volume of the same meaning.

Extensive Properties

As far as extensive properties are concerned, an extensive property is a property that changes when the size of the sample varies. Examples are mass, volume, length, and total charge, and these properties depend upon the quantity of matter contained in the system, for example, mass, volume, and heat capacity.

Difference between Extensive and Intensive properties

The table below summarizes the differences between extensive and intensive properties.

Intensive Property	Extensive Property
Doesn’t vary with size or amount	Varies with size
Depend upon the material of the substance	Depend upon the quantity of substance
For example; Temperature, Density, Melting point, etc.	For example; mass, volume, length, etc.

Why is Density an Intensive Property?

So now we come to the critical question of density being an intensive or extensive property? Density does not depend on the amount of matter which is why it is an intensive property. To clarify these ambiguous terms, consider the example that a density of 3 kg of water is the same as a density of 10 kg of water.

Although there is a mass difference of 7 kg, they are both intrinsically the same (water). So their density is the same. The density of a substance depends on its material and not its amount.

Frequently Asked Questions

What is an intensive property?

An intensive property is independent of the size or amount of the substance. These include boiling point, melting point and density, etc.

How do you determine if a property is intensive or extensive?

It is easy to distinguish between intensive and extensive properties. One needs to double the mass of the system. The physical properties that change with an increase in mass are extensive. However, those physical properties that do not change with an increase in mass are intensive.

Give an example of extensive property.

Volume is an example of extensive property as it depends upon the substance’s mass and amount.

Conclusion

Thus density doesn’t depend on the mass or quantity of a substance and can be labeled as an intensive property. An excellent example has been provided for you in the following lines to clarify the intensive nature of densities.

Take a uniform lead block and divide it into two halves by cutting it. There are two blocks with the same mass and volume, but their density is still the same. Why because both of them have the same mass-to-volume ratio.

Now a very intriguing question arises about the case when the material is compressed by hammering or whatever. In this case, only the volume has changed while the mass remains unchanged.

The density is changed. Why because the state of a substance is not the same. The hammering has changed the internal configuration of the material, thus changing its density.