Download - Unique Properties of Colloids
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UNIQUE
PROPERTIES OFCOLLOIDS
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QUIZ
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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
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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 ________________
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Write solution orcolloid.
11. milk
12. saltwater
13. blood
14. pearl
15. sugar and water
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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 -
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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 -
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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 -
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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.
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ADSORPTION
- Ability of colloidalparticles to physically hold
on other molecules ontheir surface
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Charcoal is used to remove the bad odorproduced by vapors of food in the
refrigerator.
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Activated carbon is used to purify
water.
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Activated carbon is used in gas masks.
Gasmask used bythe French military .
The filter cartridge
is composed of
activated carbon.
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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 -
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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 -
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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 -
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Activated carbon, as viewed under
electron microscope
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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 -
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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.
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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.
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Colloidal particles of a given kindwill all have the SAME sign or
excess charge and willtherefore, continuously repeleach other.
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In addition to the random motionof the particles, the uniform
electrical charge of particlesalso prevents them fromcoagulating and dispersing.
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