# Science Site

## What do you Reckon: Is Perfume a Colloid?

Source: Unsplash

Let’s first answer the question directly and then we will get into the science working behind it all. Yes, perfume is a colloid. In fact deodorant, the Jell-O you love, and the cheese they put on pizza are all colloids! Bet you weren’t expecting that now were you? But let’s get back to perfumes for now.
Can you relate all the items we named above and find the things common between them? Well, in order to do that, we’ll have to answer this question first…

### What is a Colloid?

When you mix two substances together, you either get a solution or a suspension. A colloid is a kind of solution where two completely different particles are mixed together. This creates a system that is called a “heterogeneous system”.
There are two different types of solutions or “mixtures” that you need to know about:

### ⦁ Homogenous Mixture

In a homogenous mixture, when you mix two substances together, they blend in together and get distributed uniformly through the final product mixture.
For example, the air is a perfect example of a homogeneous mixture as the particles of oxygen, nitrogen, and other gases are evenly distributed. There are no boundaries between the gases that separate them; they are all evenly distributed.

### ⦁ Heterogeneous Mixture

A heterogeneous mixture is a blend of two substances in which the composition of the two isn’t distributed evenly. They are blended together, but you can definitely see the boundary between the two substances.
One example of heterogeneous mixtures is blending two different colored balls. When you mix them together, you can clearly see identify each particle and separate them if you would like to.

### Dispersed Phase and Dispersed Medium

When it comes to colloidal particles, they always have a dispersed phase and a dispersed medium. So, what is that?

### ⦁ Dispersed Phase

From the three states of matter, the dispersed phase is the state the colloidal particles exist in: solid, liquid or gas. They can be dispersed in any state with the only condition being that it should be continuously in that same state.

### ⦁ Dispersed Medium

How the dispersed phase comes out/is applied is called a medium. It can be any state of matter, like the phase, in solid, liquid, or gas. When the dispersed medium is continuous like the dispersed phase.
When we talk about perfumes, they are aerosols, a type of colloid. The dispersed phase of perfumes is liquid and the medium they get dispersed in is gaseous. Therefore, they keep floating in the air for a long time.

### Colloidal Dispersion in Aerosols

Now, as perfumes are a form of aerosol this leads us to questions about aerosols. What are they and how do they show colloidal dispersion?
Aerosols are composed of small liquid droplets or tiny solid particles that are dispersed in a gas. They are made up of ions, atoms, and molecules and are not more than 1nm in diameter. Essentially microscopic in nature.
They show classic colloidal dispersion properties that include:
⦁ The particles in all kinds of aerosols are dispersed evenly throughout the gaseous medium and never settle out from each other.
⦁ All the particles are observed to undergo Brownian movement
⦁ The particles also perform diffusion and travel from a place of higher concentration to a medium of lower concentration.

### Colloidal Properties in Fragrance – Notes of Perfumes

Another dead giveaway of perfumes being colloidal substances is the different fragrance notes that perfumes possess. There are three major notes to each perfume or fragrance when we purchase them:

### ⦁ The Top Note

The top notes, also known as the headnotes, are the notes that you first recognize when you spray perfume. They linger for a few minutes, even just seconds and then disperse. They are the first impression of a perfume that transitions into the middle notes.

### ⦁ The Middle Note

Middle notes or the heart notes are the different fragrances that follow the headnotes. They retain a little bit of the top notes but keep introducing new notes. They are the main fragrance that you smell, therefore, they last for a long time, for about 20 to 60 minutes. They also act as a buffer for the base notes.

### ⦁ The Base Note

The base notes are the foundation of a perfume, they add resonance and depth to lighter notes. They are heavy and have a long-lasting effect as they work with the middle notes and stay in the air for a long time.

Even though perfumes are made up of three different notes, all notes have their own distinct fragrance and can be distinguished from one another. The headnotes have another scent, the middle notes have their own identity and the base notes are also distinct.

### Final Words

So, now we can easily pass the final verdict that perfumes are indeed colloids as their particles show colloidal movement and properties in every way. When we spray perfume, the alcohol is quickly separated from the fragrance notes and the notes themselves also stand out from one another over a course of time. This prominent feature of perfumes helps us in the simple and clear identification of perfumes as colloids. They are apparently homogenous, chemically heterogeneous, existing in a liquid medium that turns to a gaseous phase when dispersed. They are indeed a fascinating compound… but a colloid nonetheless!