Table of Contents
What are Colloids or Colloidal Solution?
A colloid is a mixture in which one substance is finely dispersed in another substance. The dispersed substance is called the colloid phase, and the dispersion medium is called the solvent. The dispersed phase may be solid, liquid, or gas.
Colloidal solutions are suspensions of very small particles of one substance in another substance. The dispersed phase is usually a liquid, and the dispersion medium is usually a liquid or a gas.
Examples of Colloidal Solution
A colloid is a mixture of two or more substances in which one substance, the dispersed phase, is present in a much smaller amount than the other substance, the dispersion medium. In a colloidal solution, the dispersed phase is in the form of very small particles that are suspended in the dispersion medium.
Some examples of colloidal solutions are milk, paint, and blood. Milk is a colloidal suspension of fat droplets in water. Paint is a colloidal suspension of pigment particles in a solvent. Blood is a colloidal suspension of red blood cells in plasma.
1. Based on their Physical State
Solid-state materials are those that are in a solid form, whereas liquid-state materials are those that are in a liquid form.
2. Based on their Crystal Structure
Solid-state materials can also be classified based on their crystal structure. There are three main types of crystal structures: cubic, hexagonal, and tetragonal.
3. Based on their Electrical Properties
Solid-state materials can also be classified based on their electrical properties. There are three main types of electrical properties: conductor, semiconductor, and insulator.
4. Based on their Dispersion Medium
classified into four categories:
1. Liquid coatings
2. Powder coatings
3. Electrocoating
4. Thermal spray coatings
Liquid coatings are the most commonly used type of coating and are applied as a liquid to a surface. The most common type of liquid coating is paint. Liquid coatings can be used on a variety of surfaces, including metal, plastic, and wood.
Powder coatings are applied as a powder to a surface. The powder is then heated, which causes it to melt and form a coating. Powder coatings are used on a variety of surfaces, including metal, plastic, and wood.
Electrocoating is a type of liquid coating that is applied to a surface by means of an electrical current. The current causes the coating to be deposited on the surface. Electrocoating is used on a variety of surfaces, including metal and plastic.
Thermal spray coatings are applied to a surface by means of a heat source. The heat causes the coating to be deposited on the surface. Thermal spray coatings are used on a variety of surfaces, including metal and plastic.
5. Based on Interaction Forces
The interaction forces between the atoms in a molecule are responsible for the chemical properties of the molecule.
6. Based on the Structure of the Atom
The structure of the atom is responsible for the chemical properties of the molecule.
Lyophilic Colloids
These colloids are permanently soluble in water and are not affected by changes in temperature or pH. Lyophilic colloids are also called hydrophilic colloids.
Examples of lyophilic colloids include:
• Gelatin
• Agar
• Albumin
• Dextran
• Polysaccharides
Lyophobic Colloids
Some colloids are specifically designed to be repelled by water. These are called hydrophobic colloids. These colloids are made of small particles that are surrounded by a coating that makes them resistant to water. When these colloids are placed in water, the water will push the particles away from each other, preventing them from clumping together.
Preparation of Colloidal Solution of Copper
A colloidal solution is a suspension of tiny particles of one substance in another substance. In this experiment, you will prepare a colloidal solution of copper.
To prepare the colloidal solution of copper, you will need a piece of copper wire, copper sulfate, a stove, a coffee pot or teapot, and water.
1. Cut a piece of copper wire about 12 inches long.
2. Place the copper wire in a small saucepan and add enough water to cover the wire.
3. Bring the water to a boil over high heat.
4. Add enough copper sulfate to the boiling water to turn the water blue.
5. Turn the heat off and let the solution cool.
6. Pour the solution into a coffee pot or teapot.
7. Serve the solution in a glass.
Properties of Colloidal Solutions
- The particles in a colloidal solution are too small to be seen with the naked eye. Colloidal solutions are usually transparent and have a uniform appearance.
- Colloidal solutions usually have a high surface area to volume ratio. This is because the small particles have a lot of surface area compared to their volume.
- Colloidal solutions are usually unstable. This means that the particles will eventually settle out and the solution will become clear.
1. Optical Properties of Colloidal Solutions
The optical properties of colloidal solutions are determined by the size, shape, and composition of the colloidal particles.
Colloidal particles can scatter and absorb light. The scattering of light creates the Tyndall effect, which is the blue haze that is often seen in a colloidal solution. The absorption of light causes the solution to appear colored. The color of a colloidal solution is usually a function of the wavelength of light that is being absorbed.
The size of the colloidal particles affects the scattering and absorption of light. Smaller particles scatter and absorb more light than larger particles.
The shape of the colloidal particles affects the scattering and absorption of light. Spherical particles scatter and absorb more light than non-spherical particles.
The composition of the colloidal particles affects the scattering and absorption of light. Colloidal particles that are composed of different materials will scatter and absorb light differently.
2. Kinetic Properties of Colloidal Solutions
3. Brownian Motion
4. The Particle-Size Distribution of a Colloidal Solution
5. The Stability of Colloidal Solutions
6. The Electrical Properties of Colloidal Solutions
7. The Optical Properties of Colloidal Solutions
8. The Thermal Properties of Colloidal Solutions
9. The Chemical Properties of Colloidal Solutions
10. The Biological Properties of Colloidal Solutions
3. Electrical Properties of Colloidal Solutions
The electrical properties of a colloidal solution are determined by the nature of the dispersed phase and the solvent. In general, the electrical conductivity of a colloidal solution increases with the concentration of the solute. This is because the number of charged particles in the solution increases with concentration, and the greater the number of charged particles, the greater the electrical conductivity.
The electrical conductivity of a colloidal solution also depends on the nature of the dispersed phase and the solvent. In general, polar solvents (solvents that have a dipole moment) and polar solutes (solutes that have a dipole moment) produce colloidal solutions with high electrical conductivities. This is because polar solvents and polar solutes are good electrical conductors. Nonpolar solvents and nonpolar solutes produce colloidal solutions with low electrical conductivities. This is because nonpolar solvents and nonpolar solutes are poor electrical conductors.
The electrical conductivity of a colloidal solution also depends on the size of the dispersed phase particles. In general, the smaller the particles, the higher the electrical conductivity. This is because the smaller the particles, the greater the number of charged particles per unit volume and the greater the electrical conductivity.
The electrical conductivity of a colloidal solution also depends on the nature of the surface of the dispersed phase particles. In general, the greater the number of charged particles on
Important Questions
1. What is the difference between a mineral and a rock?
A mineral is a naturally occurring, inorganic, solid element or compound. A rock is a naturally occurring, inorganic, solid mass of minerals or mineraloids.
