Material for vidiocolloid nature

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colloid 

There is this daily life, often we encounter some products that are a mixture of some substances, but the substance can be mixed evenly / homogeneous. For example, when the mother makes milk for younger sister, powder / milk powder mixed evenly with hot water. Such products are colloidal systems.

Colloids are a mixture of heterogeneous substances (two phases) between two or more substances in which the colloidal particles of matter (dispersed / dispersed phases) are spread evenly in other substances (dispersing 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 colloidal system is the ink, which consists of color powders (solid) with liquid (water). In addition to ink, there are still 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 of the dispersed phase and dispersing phase with a dispersed particle size ranging from 10-7 to 

10-4 cm. The particle size dispersed does not explain the state of the particle. Particles can consist of tiny 

atoms, molecules or molecules. Colloidal gold consists of particles of different sizes, each containing millions 

of gold atoms or more. Colloidal sulfur consists of particles containing about one thousand S8 molecules. 

An example of a very large molecule (also called a macro molecule) is haemoglobin. The molecular weight 

of this molecule is 66800 s.m.a and has a diameter of about 6 x 10-7.

2.2 KOLOID TYPES

The colloidal system is composed of dispersed phases which are evenly dispersed in the dispersing medium. 

The dispersed phase and dispersing medium may be solid, liquid, and gaseous. Based on the dispersed phase, 

the colloidal system can be grouped into 3, namely:

1. Sol (solid dispersed phase)

A. Solid soles are soles in dense dispersing medium

Example: metal alloy, color glass, black diamond

B. The liquid sole is the sole in the liquid dispersing medium

Example: paint, ink, flour in water, clay

C. The gas sol is the sole in the gas dispersing medium

Example: dust in air, combustion smoke

2. Emulsion (liquid dispersed phase)

A. Solid emulsion is an emulsion in a solid dispersant medium

Example: Jelly, cheese, butter, rice

B. The liquid emulsion is an emulsion in a liquid dispersing medium

Examples: milk, mayonnaise, hand cream

C. The gas emulsion is an emulsion in a gas dispersing medium

Examples: hairspray and mosquito repellent

3. BUIH (gas dispersed phase)
A. Solid foam is a froth in a solid dispersant medium
Examples: Pumice, marshmallow, foam rubber, Styrofoam
B. Liquid foam is a froth in a liquid dispersing medium
Example: whipped egg whites, soap foam
- For grouping of froth, if the phase is dispersed and the dispersing medium
 
Both are gases, the mixture is a solution
2.3 CHOLOID PROPERTIES
Tyndall Effect
 
The Tyndall effect is a symptom of scattering of light beam (light) by colloidal particles. This is because the size
 of the colloidal molecule is quite large. This tyndall effect was discovered by John Tyndall (1820-1893), 
a British physicist. Therefore it is called the tyndall effect.
 
The tyndall effect is the effect that occurs when a solution is exposed to light. When the true solution
 (pictured left) is illuminated with light, the solution will not scatter light, whereas in the colloidal system
 (right image), the light will be scattered. It happens because the colloidal particles have relatively large
 particles to be able to scatter the rays. In contrast, in the true solution, the particles are relatively small
 so that the scattering occurs only slightly and is very difficult to observe.
 
    Brownian motion
 
Brownian motion is the movement of colloidal particles that always move straight but erratic (random motion
 / irregular). If we observe colloids under an ultra microscope, then we will see that the particles will move to 
form zigzags. This zigzag movement is called Brownian motion. The particles of a substance are constantly 
moving.

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 occurring within a particle). Example: (i) Fe (OH) 3 Colloid is positively charged

 because its surface absorbs H + ions. (Ii) As2S3 Colloid is negatively charged because its surface absorbs

 S2 ions.

    Colloidal load

Known two kinds of colloids, the colloids are positively charged and negatively charged colloids.

    Colloid coagulation

Coagulation is a clumping of colloidal particles and forming a precipitate. With the occurrence of 

coagulation, means dispersed substances no longer form colloids. Coagulation may occur physically

 such as heating, cooling and stirring or chemically such as the addition of electrolytes, mixing different 

colloidal loads.

Protective colloids

Protective colloid is a colloid that has properties to protect other colloids from the coagulation process.

    Dialysis

Dialysis is the separation of colloid from disruptive ions in this way called the dialysis process.

    Electrophoresis

Electroferesis is the event of separation of charged colloid particles by using electric current.

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