Chemistry in Suspense: Understanding Emulsions and Suspensions

by Yuvi K - December 16, 2023

Chemistry in suspended state: Introduction to Emulsions and Suspensions

Chemistry often inspires awe and suspense in the minds of its explorers. From the seemingly unlimited array of chemical reactions and products, to the mysteries of the microscopic world; chemistry has captivated and educated many for millennia.

Today, we explore the exciting realm of emulsions and suspensions- two forms of chemistry that exist in a physical state of suspense, not quite solid, liquid or gas. These physical mixtures have many practical applications and create chemistry that may easily go unnoticed to the naked eye.

What is Suspension?

A suspension is a heterogeneous mixture that contains solid particles that are visible to the naked eye, suspended within a liquid medium. These particles can range in size from nanoparticles to large chunks, and are not soluble in the medium.

The distrubution of particles in a suspension mixture is random, and the particles freely move in a three-dimensional space. Due to this free-moving motion, the particles settle out of suspension in a process known as sedimentation. Common examples of suspensions include fog, mud and dirty water.

What is an Emulsion?

An emulsion is also a heterogeneous mixture, however, in contrast to a suspension, the particles are too small to be seen. The particles in an emulsion are approximately between 0.1 to 0.5 micrometers in size, and are composed of two immiscible liquids, often referred to as the ‘dispersed and continuous phases’.

The dispersed phase is often referred to as the ‘internal phase’, as it is contained within the liquid and not visible externally. Hence, when rapidly agitated, the emulsion appears to be homogenous in nature.

An example of an emulsifying agent commonly used to form an emulsion is soap, which bonds with oil and water and allows for a stable mixture. Common examples of emulsions include salad dressings and milk.

Creation of the Suspension

The basic steps for creating a suspension can be summarised as:

1. Selecting the solvent of your choice.
2. Dispersing the solid particles in the selected solvent.
3. Stiring the mixture continuously until the solid particles are evenly distributed.

The selection of the solvent will largely depend on the solid particles that are used, and vice versa. As an example, sand would be better suspended in water than in oil, as the particles will remain suspended in water due to the cohesive force of the water molecules.

Therefore, the physical properties of the solid particles and the solvent must be taken into account when forming a suspension.

Creation of Emulsion

The formation of an emulsion is a much more complex process. An emulsifying agent, such as soap, must be used to form a stable emulsion, otherwise the two immiscible liquids will separate. This is known as an unstable emulsion, which can be created according to the following steps:

1. Select the two immiscible liquids of your choice.
2. Add a small amount of the chosen emulsifying agent.
3. Agitate the solution rapidly.

The emulsifying agent creates a bond between the two immiscible liquids, allowing for a stable mixture. The amount of emulsifying agent used will influence the stability of the emulsion, as too much or too little will result in separation of the two liquids.

Identification of Suspension and Emulsion

The two forms of chemistry can be identified through a few fundamental tests. Firstly, visual examination of the mixture can give an indication as to which form of mixture it is. Suspensions are visible to the eye, whereas emulsions can only be seen under a microscope.

Secondly, sedimentation of the mixture can be tested to determine if it is a suspension; if the particles settle out of the mixture, then it is a suspension, whereas if the mixture remains undisturbed, then it is likely an emulsion. Lastly, a simple water and oil mixture can be used to identify between the two.

If the mixture separates into two phases then it is an emulsion, whereas if it is impossible to separate the two layers, then it is most likely a suspension.

Uses of Suspension and Emulsion

Suspensions and emulsions have practical applications in many industries, including the agriculture, food, pharmaceutical and automotive industries. Suspensions are commonly used in agriculture, as pesticides and fertilisers are sold in a suspended state, enabling ease of dispersion over farmland.

In the food industry, emulsions are important in the production of margarine, which is a blend of oil and milk proteins.

Health food beverage companies will often use emulsions of oil and water when producing shakes, as they enable a homogenous mixture without additional flavours being added. Pharmaceuticals often make use of suspensions, as this allows for simple and efficient doses of medicine for patients.

Finally in the automotive industry, lubricants must be engineered in an emulsified form in order to ensure optimal performance in machine parts.

Conclusion

Suspensions and emulsions allow the exploration and experimentation of fascinating chemistry that may go unnoticed from the naked eye. These physical mixtures hold practical applications in a variety of industries, and once the basics of science are understood, this chemistry can be explored further.

Understanding the differences between suspensions and emulsions, and the ways in which they are formed and identified can enable a greater appreciation of the physical world around us. Chemistry is often a science of suspense and surprise, and the exploration of suspensions and emulsions can be an exciting way to fully appreciate the marvels of chemistry.