Emulsion vs Suspension
Mixture contains two or more substances, which are not chemically combined and only have physical interactions. Since they do not have any chemical interactions, the chemical properties of the individual substances retain without change in a mixture, but the physical properties like melting point, boiling point can be different in a mixture compared to its individual substances. Therefore, the components of a mixture can be separated using these physical properties. For example, hexane can be separated from a mixture of hexane and water, because hexane boils and evaporates before water does. The amount of substances in a mixture can vary, and these amounts do not have a fixed ratio. Therefore, even two mixtures containing similar types of substances can be different, due to the difference in their mixing ratios. Solutions, alloys, colloids, suspensions are the types of mixtures. Mixtures can be mainly divided into two, as homogenous mixtures and heterogeneous mixtures. A homogenous mixture is uniform; therefore, the individual components cannot be separately identified, but a heterogeneous mixture has two or more phases and the components can be individually identified.
Colloidal solution is seen as a homogeneous mixture, but it can be heterogeneous as well (e.g. milk, oil in water). Emulsion is a subset of colloid; therefore, it has most of the characteristic of a colloid. The particles in emulsion are of intermediate size (larger than molecules) compared to particles in solutions and suspensions. These particles or droplets are not solid in nature. Therefore, compared to other colloids, emulsion differs because the particles and the medium are both liquids. The particles in an emulsion are termed as dispersed material, and the dispersing medium (continuous phase) is analogous to the solvent in a solution. If two liquids are combined together, a colloid known as emulsion can result (e.g. milk). For this, the two solutions must be immiscible. Emulsions are translucent or opaque. Their properties depend on many factors like temperature, droplet size, droplet distribution, amount of dispersed material etc. Emulsions do not form spontaneously since they are unstable. They form upon shaking, stirring, or mixing by any means. The droplets in an emulsion can get together and form larger droplets when mixing like this. An emulsifier can be added to this to increase the stability. Surfactants can act as emulsifiers thus, increase the kinetic stability of the emulsion.
Suspension is a heterogeneous mixture of substances (E.g. muddy water). There are two components in a suspension, the dispersed material and the dispersion medium. There are larger solid particles (dispersed material) distributed in a dispersion medium. The medium can be a liquid, gas or a solid. If the suspension is allowed to stand still for some time, the particles can be settled down to the bottom. By mixing it, a suspension can be formed again. The particles in a suspension are visible to the naked eye, and through filtration, they can be separated. Because of the larger particles, the suspensions tend to be opaque and not transparent.
What is the difference between Emulsion and Suspension?
• Emulsion is a combination of two immiscible liquids whereas, in a suspension, the two components can be of any phase.
• The stability of emulsions can be increased by adding emulsifiers.
• The particles in a suspension can be separated by filtering, but particles/droplets in an emulsion cannot be separated by filtering.