Hint: A colloidal state of matter is the state in which the size of the particles lies in between 1 nm and 100 nm and the systems consisting of dispersed particles in this range are called colloidal systems.
Complete step by step solution:
Step 1
The dispersed phase of a colloidal system is defined as the phase constituting the colloidal particles. The dispersion medium is the medium in which the colloidal particles are dispersed.
Depending upon the physical state of the dispersed phase and the dispersion medium, there are eight types of the colloidal system.
| Dispersed phase | Dispersion medium | The common name of the system |
| Solid | Solid | Solid sol |
| Solid | Liquid | Sol |
| Solid | Gas | Aerosol of solid |
| Liquid | Solid | Gel |
| Liquid | Liquid | Emulsions |
| Liquid | Gas | Aerosol of liquid |
| Gas | Solid | Solid foam |
| Gas | Liquid | Foam or froth |
Step 3
In a colloidal system when both the dispersion medium and the dispersed phase are liquid is called emulsions. There are two types of emulsions:
-Oil-in-water type of emulsion, for example, milk, ice cream, etc.
-Water-in-oil type of emulsion, for example, cod liver oil.
Step 4
Generally, emulsions are prepared by subjecting the two immiscible liquids in a high speed mixing machine or ultrasonic vibrators. The process is known as emulsification. As the two liquids used for the preparation of an emulsion are completely immiscible, a stabilizing substance, known as an emulsifying agent or emulsifier is required to stabilize the resulting emulsion.
Gelatin is an emulsifier that is added to ice cream to stabilize the emulsion and give it a soft texture and a fresh look. In the emulsifying action, it prevents the crystallization in ice cream by reducing the water content.
Hence, the emulsion ice cream is stabilized by adding gelatin to it.
Note: The emulsifiers form a protective film around the oil component dispersed in water which prevents them to come closer and aggregate. Thus the emulsion gets stabilized.
