What is a colloid? Solution: A colloid is a type of homogeneous mixture where tiny particles of one substance are dispersed, but not dissolved, in another substance. The particles are typically between 1 and 1000 nanometers in diameter.
- What are the two phases of a colloid? Solution: A colloid consists of two phases: the dispersed phase, which is the particles or droplets being dispersed, and the dispersion medium, which is the substance in which the dispersed phase is distributed.
- Name five types of colloids, based on the states of the dispersed phase and the dispersion medium. Solution: Examples of colloids based on the states of the dispersed phase and the dispersion medium are: solid/liquid (sol), liquid/liquid (emulsion), gas/liquid (foam), liquid/gas (aerosol), and solid/gas (smoke).
- What is the Tyndall effect? Solution: The Tyndall effect is the scattering of light by particles in a colloid or a very fine suspension. This makes a beam of light visible as it passes through the colloid.
- How are colloids different from solutions and suspensions? Solution: Colloids differ from solutions and suspensions in terms of particle size. In solutions, particles are individual molecules or ions, which are much smaller than those in a colloid. Suspensions contain larger particles that will settle out over time, while the particles in a colloid will not.
- What is Brownian motion and what role does it play in colloids? Solution: Brownian motion is the random motion of particles in a fluid (liquid or gas) resulting from their collision with fast-moving molecules in the fluid. This motion prevents the particles in a colloid from settling out.
- How can colloids be separated? Solution: Colloids can be separated by techniques such as centrifugation and ultrafiltration, which exploit the size of the colloidal particles.
- What are hydrophilic and hydrophobic colloids? Solution: Hydrophilic colloids have particles that are attracted to water, while hydrophobic colloids have particles that repel water.
- What is an emulsion? Solution: An emulsion is a type of colloid in which both the dispersed phase and the dispersion medium are liquids. An example is milk, which is a water-based liquid containing dispersed fat droplets.
- What is coagulation in the context of colloids? Solution: Coagulation, or flocculation, refers to the process in which the dispersed particles in a colloid aggregate to form larger particle clusters, which can then be separated from the dispersion medium.
- What is a colloidal system? Solution: A colloidal system refers to a system in which one substance of microscopically dispersed insoluble particles is suspended throughout another substance.
- What role do emulsifiers play in colloidal systems? Solution: Emulsifiers stabilize colloidal systems by reducing the surface tension between the dispersed phase and the dispersion medium. This prevents the dispersed particles from aggregating and separating out.
- What is an aerosol? Solution: An aerosol is a type of colloid in which solid particles or liquid droplets are dispersed in a gas.
- What are micelles? Solution: Micelles are aggregates of surfactant molecules dispersed in a liquid colloid. They form when the concentration of the surfactant is above the critical micelle concentration (CMC).
- Why is milk considered a colloidal system? Solution: Milk is considered a colloidal system because it is composed of butterfat globules dispersed in water, with proteins forming a colloidal solution.
- What happens when a colloid undergoes dialysis? Solution: Dialysis of a colloid allows the small ions or molecules to pass through a semipermeable membrane, but the larger colloidal particles cannot pass through.
- Why do colloidal particles not settle down under the influence of gravity? Solution: Colloidal particles do not settle under the influence of gravity due to the small size of the particles and the ongoing random movements of particles known as Brownian motion.
- What is an example of a natural colloid? Solution: A natural colloid example is blood, which is a colloidal dispersion of blood cells in plasma.
- What is meant by the protective action of colloids? Solution: The protective action of colloids refers to their ability to prevent the coagulation of a colloidal system. Certain colloidal particles can absorb ions onto their surface, providing a charge that keeps other particles in the system dispersed.
What is peptization? Solution: Peptization is the process of converting a precipitate into a colloidal solution by shaking it with the dispersion medium in the presence of a small amount of electrolyte. The electrolyte provides a charge on the particles of the precipitate, allowing them to repel each other and become dispersed throughout the medium.
