unique properties of colloids

7/28/2019 Unique Properties of Colloids

1/24

UNIQUE

PROPERTIES OFCOLLOIDS


2/24

QUIZ


3/24

Identify the following examples as to

the types of colloids.

1. fog2. dust in air

3. meringue4. cheese5. ruby

6. whipped cream7. mayonnaise8. fruit jellies


4/24

Identify what is being described.

9. consists of colloidal particles,comparable to the solute in a

solution ______________10. the substance in which the

colloidal particles are distributed

comparable to the solvent in asolution ________________


5/24

Write solution orcolloid.

11. milk

12. saltwater

13. blood

14. pearl

15. sugar and water


6/24

1. TYNDALL EFFECT

- Scattering of light due to colloidalparticles

- Named after the British physicist JohnTyndall who critically investigated thephenomenon in 1869
http://c/Users/judy/Videos/Efecto%20Tyndall%20fluorescente_1.wmv


7/24

2. BROWNIAN MOVEMENT

- Zigzag, random motion of dispersedparticles through the dispersionmedium

- Named after the British botanist RobertBrown who first studied thephenomenon in 1827

Brownian movement is the reason whycolloidal particles do not settle down onstanding.
http://c/Users/judy/Videos/Brownian%20Motion.wmv


8/24

3. ADSORPTION

How is adsorption different fromabsorption? If you place a fewdrops of water onto a cottonball, the water droplets areimmediately soaked up by the

cotton. This is absorption.
http://c/Users/judy/Desktop/YouTube%20%20%20%20%20%20%20%20-%20Absorption%20And%20Adsorption.mp4


9/24

On the other hand, adsorption iswhen you use the cotton ball

against the chalkboard. Observeclosely what happens to the cotton.Chalk particles and dust adhered to

the surface. This phenomenon iscalled adsorption.


10/24

ADSORPTION

- Ability of colloidalparticles to physically hold

on other molecules ontheir surface


11/24


12/24

Charcoal is used to remove the bad odorproduced by vapors of food in the

refrigerator.


13/24

Activated carbon is used to purify

water.


14/24

Activated carbon is used in gas masks.

Gasmask used bythe French military .

The filter cartridge

is composed of

activated carbon.


15/24

Activated carbon is used to treat

poisonings and overdoses following oral

ingestion.
http://en.wikipedia.org/wiki/Poisonhttp://en.wikipedia.org/wiki/Overdosehttp://en.wikipedia.org/wiki/Ingestionhttp://en.wikipedia.org/wiki/Ingestionhttp://en.wikipedia.org/wiki/Overdosehttp://en.wikipedia.org/wiki/Poison


16/24

Tablets or capsules of activated

charcoal are used in many countries as

an over-the-counter drug to treat

diarrhea, indigestion, and flatulence.
http://en.wikipedia.org/wiki/Tablethttp://en.wikipedia.org/wiki/Capsuleshttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Diarrheahttp://en.wikipedia.org/wiki/Indigestionhttp://en.wikipedia.org/wiki/Flatulencehttp://en.wikipedia.org/wiki/Flatulencehttp://en.wikipedia.org/wiki/Indigestionhttp://en.wikipedia.org/wiki/Diarrheahttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Over-the-counter_drughttp://en.wikipedia.org/wiki/Capsuleshttp://en.wikipedia.org/wiki/Tablet


17/24

Activated charcoal is also used in

spacesuitPrimary Life Support

Systems.

A Primary (also Portable or Personal) Life

Support System/Subsystem, or PLSS, is the

"backpack" of a spacesuit. It provides most of

the functions of a spacecraft life support

system, in a smaller package.
http://en.wikipedia.org/wiki/Spacesuithttp://en.wikipedia.org/wiki/Primary_Life_Support_Systemhttp://en.wikipedia.org/wiki/Primary_Life_Support_Systemhttp://en.wikipedia.org/wiki/Spacesuithttp://en.wikipedia.org/wiki/Life_support_systemhttp://en.wikipedia.org/wiki/Life_support_systemhttp://en.wikipedia.org/wiki/Life_support_systemhttp://en.wikipedia.org/wiki/Life_support_systemhttp://en.wikipedia.org/wiki/Spacesuithttp://en.wikipedia.org/wiki/Primary_Life_Support_Systemhttp://en.wikipedia.org/wiki/Primary_Life_Support_Systemhttp://en.wikipedia.org/wiki/Spacesuit


18/24

Activated carbon, as viewed under

electron microscope


19/24

Properties of Activated Carbon

A gram of activated carbon can have a surface area inexcess of 500 m2, with 1500 m2 being readily achievable.Carbon aerogels, while more expensive, have even highersurface areas, and are used in special applications.

Activated carbon, as viewed by an electron microscope

Under an electron microscope, the high surface-areastructures of activated carbon are revealed. Individualparticles are intensely convoluted and display various kindsofporosity; there may be many areas where flat surfaces ofgraphite-like material run parallel to each other, separatedby only a few nanometers or so. These micropores providesuperb conditions for adsorption to occur, since adsorbingmaterial can interact with many surfaces simultaneously.
http://en.wikipedia.org/wiki/Aerogelhttp://en.wikipedia.org/wiki/Aerogelhttp://en.wikipedia.org/wiki/Electron_microscopehttp://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Adsorptionhttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Adsorptionhttp://en.wikipedia.org/wiki/Adsorptionhttp://en.wikipedia.org/wiki/Microporehttp://en.wikipedia.org/wiki/Graphitehttp://en.wikipedia.org/wiki/Porosityhttp://en.wikipedia.org/wiki/Electron_microscopehttp://en.wikipedia.org/wiki/Aerogel


20/24

APPLICATION OF ADSORPTION

use of aluminum hydroxide inpurifying water

Use of activated carbon in refiningsugar and electroplating solutions

use of bone black in gas masks toremove toxic gases in the air.


21/24

4. UNIFORM ELECTRICAL CHARGE

A dispersed colloidal particle canadsorb (or bind) electrically

charged particles (ions) on itssurface. The charged speciesadsorbed on the surface of a given

kind of colloidal particle may beeither positive or negative.


22/24

Colloidal particles of a given kindwill all have the SAME sign or

excess charge and willtherefore, continuously repeleach other.


23/24

In addition to the random motionof the particles, the uniform

electrical charge of particlesalso prevents them fromcoagulating and dispersing.


24/24

unique properties of colloids

Documents