Rabu, 22 Maret 2023

Colloid System Paper: Definition, Types, Properties, Components, and the Latest Manufacturing Process

Colloid System Paper: Definition, Types, Properties, Components, and Manufacturing Process

A. Background

The colloid system is a form of a mixture of two or more substances that is homogeneous but has a large enough dispersed particle size (1 - 100 nm), so it is subject to the Tyndall effect. Being homogeneous means that the dispersed particles are not affected by gravitational forces or other forces imposed on them; so that no precipitation occurs, for example. This homogeneous property is also owned by the solution, but not owned by ordinary mixtures (suspensions).

Colloids are easy to find everywhere: milk, jelly, ink, shampoo , and clouds are examples of colloids that can be found everyday. The cytoplasm in the cell is also a colloidal system. Colloid chemistry is a separate study in industrial chemistry because of its importance.

B. Problem Formulation

a. What is meant by colloid system?

b. Describe the different types of colloid systems?

c. What are the properties of colloids?

d How is the process of making a colloid system?

e. What are the components of the colloid system, the shape of the particles and their uses in everyday life?

C. Purpose

a. So that the reader can know the colloid system.

b. In order for the reader to know the various colloid systems.

c. In order for the reader to know the properties of colloids.

d. So that the reader knows the process of making colloidal systems.

e. In order for the reader to know the components of the colloid system, the shape of the particles and their uses in everyday life.

D. Benefits

a. Readers can know the colloid system.

b. Readers know the various colloid systems.

c. Readers know the properties of colloids.

d. The reader knows the process of making colloid systems.

e. Readers know the components of the colloid system, the shape of the particles and their uses in everyday life.



A. Definition of Colloid

A colloid is a heterogeneous mixture of substances (two phases) between two or more substances in which colloid-sized particles of substance (dispersed/broken phase) are spread evenly in another substance (dispersing/breaking medium). The size of colloidal particles ranges from 1-100 nm. The size in question can be the diameter, length, width, or thickness of a particle. Another example of a colloid system is ink, which consists of colored powders (solid) and liquid (water). Apart from ink, there are many other colloidal systems, such as mayonnaise, hairspray, jelly, etc.

The colloidal state or colloidal system or colloidal suspension or colloidal solution or a colloid is a two-phase mixture, namely the dispersed phase and the dispersing phase with dispersed particle sizes ranging from 10-7 to 10-4 cm. The size of the dispersed particles does not explain the state of the particles. Particles can consist of atoms, small molecules or very large molecules. Colloidal gold consists of particles of various sizes, each of which contains millions or more gold atoms. Colloidal sulfur consists of particles containing about a thousand S8 molecules. An example of a very large molecule (also called a macromolecule) is haemoglobin. The molecular weight of this molecule is 66800 amu and has a diameter of about 6 x 10-7.

B. Types of Colloids

The colloidal system is composed of the dispersed phase which is evenly distributed in the dispersion medium. The dispersed phase and the dispersing medium can be solid, liquid or gaseous. Based on the dispersed phase, colloidal systems can be grouped into 3, namely:

1. Sol (solid dispersed phase)

a. The solid sole is the sole in the dispersing medium

Examples: metal alloys, colored glasses, black diamonds

b. Liquid sol is a sol in a liquid dispersing medium

Examples: paint, ink, flour in water, clay

c. A gas sol is a sol in a gas dispersing medium

Example: dust in the air, combustion smoke

2. Emulsion (liquid dispersed phase)

a. Solid emulsion is an emulsion in a solid dispersing medium

Example: Jelly, cheese, butter, rice

b. Liquid emulsion is an emulsion in a liquid dispersing medium

Example: milk, mayonnaise, hand cream

c. Gas emulsion is an emulsion in a gas dispersion medium

Example: hairspray and insect repellent

3. Froth (gas dispersed phase)

a. A dense foam is a foam in a dense dispersing medium.

Examples: Pumice, marshmallow, foam rubber, Styrofoam

b. Liquid froth is foam in a liquid dispersing medium

Examples: whipped egg whites, soap suds

For foam grouping, if the dispersed phase and the dispersion medium are both gases, the mixture is classified as a solution

C. Properties of Colloids

a. Tyndall effect

The Tyndall effect is a phenomenon of scattering of light rays (light) by colloidal particles. This is due to the relatively large size of colloid molecules. The Tyndall effect was discovered by John Tyndall (1820-1893), an English physicist. Therefore, the nature of the so-called Tyndall effect.

Tyndall effect is the effect that occurs when a solution is exposed to light. When the true solution (left image) is irradiated with light, the solution will not scatter light, whereas in the colloid system (right image), the light will be scattered. it happens because colloidal particles have relatively large particles to be able to scatter the light. In contrast, in a true solution, the particles are relatively small so that the scattering that occurs is small and very difficult to observe.

b. Brownian motion

Brownian motion is the motion of colloidal particles which always move straight but erratically (random/irregular motion). If we observe colloids under an ultra microscope, we will see that the particles will move in a zigzag shape. This zigzag movement is called Brownian motion. The particles of a substance are always in motion.

The motion can be random as in liquids and gases, or just vibrate in place as in solids. For colloids with a liquid or gas dispersing medium, the movement of the particles will result in collisions with the colloidal particles themselves. The collision took place from all directions. Because the particle size is quite small, the collisions that occur tend to be unbalanced. So that there is a resultant collision that causes a change in the direction of motion of the particles resulting in zigzag motion or Brownian motion. The smaller the size of the colloidal particles, the faster Brownian motion occurs. Likewise, the larger the size of the colloidal particles, the slower the Brownian motion occurs. This explains why Brownian motion is difficult to observe in solution and is not found in solids (suspensions). Brownian motion is also affected by temperature. The higher the temperature of the colloidal system, the greater the kinetic energy of the dispersion medium particles. As a result, the Brownian motion of the dispersed phase particles accelerates. Vice versa, the lower the temperature of the colloid system, the slower the Brownian motion.

c. Absorption

Absorption is the absorption of particles or ions or other compounds on the surface of colloidal particles caused by the surface area of ​​the particles. (Note: Absorption must be distinguished from absorption, which means absorption that occurs within a particle). Example: (i) Colloidal Fe(OH)3 has a positive charge because its surface absorbs H+ ions. (ii) As2S3 colloid has a negative charge because its surface absorbs S2 ions.

d. Colloidal charge

Two kinds of colloids are known, namely positively charged colloids and negatively charged colloids.

e. Colloid coagulation

Coagulation is the clumping of colloidal particles and forming precipitates. With the occurrence of coagulation, it means that the dispersed substances no longer form colloids. Coagulation can occur physically such as heating, cooling and stirring or chemically such as adding electrolytes, mixing colloids with different charges.

f. protective colloid

Protective colloids are colloids that have properties that can protect other colloids from the coagulation process.

g. Dialysis

Dialysis is the separation of colloids from interfering ions in this way is called the process of dialysis.

h. Electrophoresis

Electropheresis is the separation of charged colloidal particles using an electric current.

D. Making a colloid system

Double decomposition reaction

For example:
Sol As2S3 is made by flowing H2S slowly through a cold As2O3 solution until a bright yellow sol As2S3 is formed;

As2O3 (aq) + 3H2S(g) to As2O3 (koloid) + 3H2O(l)

(As2S3 colloid is negatively charged because its surface absorbs S2- ions)

Sol AgCl was prepared by mixing aqueous AgNO3 solution and dilute HCl solution;

AgNO3 (ag) + HCl (aq) à AgCl (koloid) + HNO3 (aq)

Nitrate heating

When heated, most nitrates tend to decompose to form metal oxides, nitrogen dioxide in the form of brown smoke, and oxygen.

For example, simple Group 2 nitrates such as magnesium nitrate undergo decomposition in the following reaction:

In Group 1, ithium nitrate undergoes the same decomposition process - yielding lithium oxide, nitrogen dioxide and oxygen. However, nitrates from elements other than lithium in Group 1 do not decompose completely (at least not at the Bunsen temperature) - giving metallic nitrite and oxygen, but not nitrogen oxides. All nitrates from sodium to cesium decompose according to the above reaction, the only difference being the heat that must be experienced for the reaction to occur. As you go down the group, the decomposition is more difficult, and higher temperatures are required.

Carbonate heating

When heated, most carbonates tend to decompose to form metal oxides and carbon dioxide. For example, simple Group 2 carbonates such as calcium carbonate decompose as follows:

In Group 1, lithium carbonate undergoes the same decomposition process to produce lithium oxide and carbon dioxide.

The carbonates of elements other than lithium in Group 1 do not decompose at the Bunsen temperature, although at higher temperatures they do. The decomposition temperature again increases as you go down the Group.

E. Use of colloids

The colloid system is widely used in everyday life, especially in everyday life. This is due to the important characteristics of colloids, which can be used to mix substances that are not able to dissolve each other in a homogeneous manner and are stable for production on a large scale.

The following is a table of colloid applications:

Industry type

Application examples

Food industry

Cheese, butter, milk, salad dressing

Cosmetics and body care industry

Cream, toothpaste, soap

Paint industry


Household needs industry

Soap, detergent

Agricultural industry

Pepticide and insecticide

Pharmaceutical industry

Fish oil, pencilin for injection

The following is an explanation of colloid applications:

1. Sugar Bleaching

Cane sugar that is still colored can be bleached. By dissolving sugar in water, then the solution flows through the colloidal system of diatomaceous earth or carbon. Colloidal particles will adsorb the dye. The colloidal particles adsorb the dyes from cane sugar so that the sugar turns white.

2. Blood Clots

Blood contains a number of negatively charged protein colloids. If there is a wound, the wound can be treated with a styptic pencil or alum which contains Al3+ and Fe3+ ions. These ions help the colloidal particles in the protein to be neutral so that the blood clotting process can be done more easily.

3. Water Purification

Tap water (PDAM) that exists today contains colloidal particles of clay, silt, and various other particles that are negatively charged. Therefore, to make it suitable for drinking, several steps must be taken so that the colloidal particles can be separated. This is done by adding alum (Al2SO4)3. The Al3+ ion contained in the alum will be hydrolyzed to form colloidal particles Al(OH)3 which are positively charged through the reaction:

Al3+ + 3H2O to Al(OH)3 + 3H+

After that, Al(OH)3 removes the negative charges from the colloidal particles of clay/mud and coagulation occurs in the mud. The mud then settles with the alum which also settles under the influence of gravity. The following is a complete water purification process scheme.



A. Conclusion

- Colloidal particles can scatter light so that the beam of light passes through the colloidal system. It can be observed from the side that the nature of colloidal particles is called the Tyndall effect.

- If observed with an ultra microscope, it turns out that colloidal particles are always moving with a broken motion, which is called Brownian motion. Brownian motion occurs due to unsymmetrical collisions between medium molecules and colloidal particles.

- Colloids can adsorb ions or other substances on their surface, and because of their relatively large surface area, colloids have great adsorption power.

- Adsorption of ions by colloidal particles makes colloidal particles become electrically charged. Colloidal charges cause repulsive forces between colloidal particles, so they become stable (do not experience sedimentation).

- The charge of colloidal particles can be demonstrated by electrophoresis, namely the movement of colloidal particles in an electric field.

- Clumping of colloidal particles is called coagulation. Coagulation can occur for various reasons, for example in the addition of electrolytes. The addition of electrolyte will neutralize the colloid charge, so that the stabilizing factor is lost.

- Colloids in which the dispersion medium is in the form of a liquid are divided into lyophilic colloids and lyophobic colloids. Lyophilic colloids have a strong interaction with the medium; conversely, in lyophobic colloids the interaction does not exist

- Colloids can be prepared by means of dispersion or condensation. In the dispersion method, the coarse material is crushed and then dispersed into the dispersion medium. In the condensation method, colloids are prepared from a solution in which atoms or molecules undergo aggregation (grouping), so that they become colloidal particles.

- Smog is a form of pollution which is a colloidal system.


Purba, Michael. 2010. Chemistry for Class XI High School. Jakarta: ERLANGGA

Parning, et al. 2006. Second Semester Class XI High School Chemistry. Jakarta: Yudhisthira. Suharsini, Maria. 2005. Chemistry and Life Skills. Jakarta : Ganesha Exact.

Source: mykoloid

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