[Chemistry Class Notes] on Colloids Pdf for Exam

A colloid is a mixture of particles between 1 and 1000 nanometers in diameter, yet it is still capable of being evenly distributed throughout the solution. They are also referred to as colloidal dispersions because the substances remain dispersed and do not settle down on the bottom of the container.

 

These particles may either dissolve macromolecules or have a macromolecular structure produced from smaller structural units or may represent a separate phase, such as aerosols, powders, dispersions of pigments, emulsions, or even finely pigmented plastics.

 

Such multiphase colloids described above make an account of the properties of both the phases as well as the interface between them, and hence their investigation is a natural adjunct in the study of the interface, reaching down to the size of colloid particles.

Example of Colloidal Solution

Still, the use of colloids vs. crystalloids is specifically very controversial. A colloid preferred by a physician or usually by a plasma expander can work better if colloids are present instead of crystalloids. Many colloids may contain albumin that is equally osmotic to plasma and 25% of the solutions.

 

Colloids are able to pull fluids into the bloodstream. Their effects last for several days if the lining of the capillaries is normal.

 

The majority of these colloid solutions have the below characteristics.

• Thermal kinetic energy to help the mobility

• Inertial effects absence from fluids

• Either none or negligible gravitational effects

• Type of interactions due to electromagnetic radiation

• We get to see milk at home, which is supposed to be the Colloid’s best example, the shampoo that we use, a liquid hand wash we use, and, moreover, a liquid metal polisher that we usually use at home.
  

Examples of Colloids Chemistry

The colloidal dispersion properties are closely linked to the high surface area of the dispersed phase, and these interfaces chemistry. The natural combination of this colloid and surface chemistry represents a primary research space, and we can see a variety of categories of colloids depending on these basic properties.

 

The example for colloidal solution can be given as smog, fog, and sprays.

 

For these colloid examples, the dispersed phase is liquid and a dispersion medium of gas. Usually, these are termed as a liquid aerosol.

 

Examples of colloid chemistry are dust and smoke in the air.

 

For these colloid examples, the dispersed phase is solid, and the medium is gas. This is defined as a solid aerosol.

 

The large difference in surface area of colloids and attachments follows the natural fact that specific matter has a high surface area to its mass ratio, and this leads to a surface property of the as a colloidal solutions factor.

 

For example, possibly the organic dye or pollutant molecules can be removed effectively from water by the adsorption method onto particulate activated charcoal. This happens because of the high surface area of coal. This process and property are used widely for water purification and all kinds of oral treatments.

 

The bulk of liquid molecules can interact via attractive forces with a huge nearest neighbor than those at the surface. The surface molecules must have higher energy than those in bulk because they are partially freed from bonding with the neighboring molecules.

 

Work needs to be done to pull out fully interacting molecules from the bulk of liquid to create any new surface. This gives rise to either surface energy or liquid tension and therefore the stronger the molecular force between liquid molecules, the greater the work accomplished.

Types of Colloids with Examples

Colloids are classified as per the state of dispersed medium and phase.

 

Any of the Colloids with water as a dispersing medium is divided as hydrophobic or hydrophilic. It is the one where only weak attractive forces exist between the water and the colloidal particle surface.

 

The precipitation of silver chloride would be the best example, and the result ends up as colloidal dispersion. The precipitation reaction occurs too fast for ions to gather from long distances and produce large crystals. Ions are aggregated to form small particles that remain suspended in the liquid.

 

By introducing ions into the dispersing medium, a stable hydrophobic colloid can be produced to coagulate.

 

For example, milk contains a colloidal suspension of protein-rich casein micelles with a hydrophobic core. Lactose is converted to lactate and hydrogen ions when milk ferments. The protective charge on the colloidal particles’ surface is overcome, and the milk coagulates to produce clumps of curds.

 

The soil particles are often carried by river and stream water as hydrophobic colloids. Thus, the particles coagulate to form silt at the river basin when the river meets the seawater having high salt concentrations.

 

In comparison, the water treatment plants of the municipality often add salt like aluminum sulphate to clear the water. Where aluminum ions hydrated cations neutralize the hydrophobic colloidal soil particles charge, allowing the particles to aggregate and settle out.

 

In all these particular cases, the liquid is strongly absorbed onto the surface of the particle by making an interface between particle and liquid, which is the same between liquid and itself. It makes the system inherently stable because of the reduction in Gibbs’s free energy when the particles are dispersed.

Property of Colloid Particles

• Colloids are insoluble particle mixes (sometimes known as colloidal solutions or colloidal systems). They depict the microscopic dispersion of one substance as well as a suspension in another substance. In a colloid, the size of these suspended particles can range from 1 to 1000 nanometres (10-9 meters). A colloid is a combination of particles with diameters ranging from 1 to 1000 nanometers that may spread uniformly across a solution. Colloids are heterogeneous in nature.

• Colloidal dispersions are made up of particles that are substantially larger than conventional solution solutes. Colloidal particles are large molecules or clusters of smaller species that scatter light. On a macroscopic (visual) size, colloids are homogeneous, whereas solutions are homogeneous on a microscopic (molecular) scale.
  

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Classification of Colloids 

The phase of the dispersed substance and the phase in which it is disseminated are used to classify colloids. Liquids, emulsions, foams, and aerosols are examples of colloids.

• A colloidal dispersion of solid particles in a liquid is known as sol..

• Emulsion is the combination of two liquids.

• When a large number of gas particles are trapped in a liquid or solid, foam is created.

• Aerosols are microscopic liquid or solid particles suspended in a gaseous medium.
  

The Tyndall Effect is a simple method for assessing if a combination is colloidal or not. When light is shone through a true solution, it passes through it cleanly; however, when light is shone through a colloidal solution, the substance in the scattered phases scatters the light in all directions, making it visible. A flashlight shining through fog can demonstrate this. Because the fog is a colloid, the light beam is plainly visible.

Methods of Preparation

Colloids can be made in two different methods.

• Milling, spraying, or the use of shear disperses big particles or droplets to colloidal size (e.g., shaking, mixing, or high shear mixing).

• By precipitation, condensation, or redox processes, small dispersed molecules are condensed into bigger colloidal particles. Colloidal silica and gold are both made using these techniques.
  

Applications of Colloids

Colloids have a wide range of uses. Among them are the following:

1. Medicines: Colloidal medicines are more efficient since they are easily absorbed by bodily tissues.

2. Soap has a cleansing impact since it is colloidal in nature. It either adsorbs dirt particles or emulsifies oily substances stuck to the fabric to eliminate them.

3. Water purification: Certain electrolytes, such as alum, can be used to precipitate colloidal pollutants present in water. The Al3+ ions neutralize the negatively charged colloidal particles of contaminants, which settle down and allow pure water to be decanted off.

4. Latex is a colloidal solution containing negatively charged rubber particles used in the rubber industry. Rubber can be made from latex via coagulation. Rubber-plated products are made by depositing negatively charged rubber particles over the item to be rubber plated, effectively turning the item into an anode in a rubber plating bath.