What are the properties of colloids and how do they differ from solutions?

Colloids have larger particles than solutions, resulting in unique properties such as Tyndall effect and Brownian motion.

Colloids are mixtures where the particles are larger than in solutions but smaller than in suspensions. The particles are usually between 1 and 1000 nanometers in size and are dispersed throughout a medium. Colloids can be classified into four types: sols, gels, emulsions, and aerosols. One of the unique properties of colloids is the Tyndall effect, where the particles scatter light, making the mixture appear cloudy. This effect is not observed in solutions.

Another property of colloids is Brownian motion, where the particles move randomly due to collisions with the surrounding molecules. This motion is caused by the thermal energy of the medium and is not observed in solutions. Colloids can also be stabilized by adding a surfactant or by electrostatic repulsion between the particles.

Colloids have practical applications in various fields such as medicine, food, and cosmetics. For example, emulsions are used in food products to prevent separation of oil and water-based ingredients. In medicine, colloids are used as drug delivery systems due to their ability to pass through cell membranes. Understanding the properties of colloids is important in developing new technologies and improving existing ones.