Our objective is to study the effectiveness of different common oils (castor oil, cotton seed oil, coconut oil, kerosene oil, mustard oil) in forming emulsions.
Emulsions are an important class of the colloidal system. It is a liquid-liquid colloidal system in which the dispersed phase and dispersion medium are liquids. Emulsions are a mixture of two or more immiscible liquids that are normally immiscible. They have the property to scatter the light passed through them, called Tyndall effect.
If the emulsion scatters all light equally, it becomes white. If the emulsion is dilute, the low wavelength light will be scattered more and it becomes bluer and if it is more concentrated, the longer wavelength light will be more scattered and emulsion becomes more yellow.
A few examples are milk and mayonnaise.
Emulsions can be classified into different types.
Stability of an emulsion refers its ability to resist the change in its properties. Emulsions are often recognised by their cloudy white appearance, since the substances do not mix together in a unified manner. After a short time, the mixed substances separate into different layers by various manners. This is called the instability of emulsion. There are four different types of instability in emulsions:
The process of making emulsions is known as emulsification. Emulsions can be obtained by vigorously agitating a mixture of both the liquids. But these emulsions are thermodynamically unstable because the dispersed droplets at once come together and form separate layers. The emulsions therefore need to be stabilised.
There are several ways by which emulsions can be stabilised. One method is the addition of small quantity of third substances known as emulsifying agents.
An emulsifying agent also called emulsifier is a substance that stabilises the emulsion by lowering the interfacial tension between the two immiscible liquids. It is also called stabiliser because it stabilises the emulsion. Soaps and detergents are most commonly used emulsifiers. They coat the drops of the emulsion and check them from coming together and stabilises the emulsion.
For example, soap molecules have a polar head and a non-polar hydrocarbon tail. The polar head is hydrophilic (water loving) in nature and the non-polar tail is hydrophobic (oil loving) in nature. When soap solution is added into an emulsion of oil-in-water, the polar head dissolves in the water phase and the non-polar tail dissolves in the oil droplets there by stabilising the emulsion.
Cite this Simulator: