Colloids

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Colloids : 

Colloids Solid Sol

Colloids : 

Colloids A colloid is a substance microscopically dispersed evenly throughout another one. A colloidal system consists of two separate phases: a dispersed phase and a continuous phase. A colloidal system may be solid, liquid, or gaseous.

Solid Sol : 

Solid Sol A solid sol is a colloid where the continuous phase and the disperse phase are solids. The dispersed substance is called the disperse phase and the substance it is dispersed in is called the disperse phase.

Structure of Particles : 

Structure of Particles The dispersed-phase particles have a diameter of between approximately 5 and 200 nanometers. Such particles are normally invisible to an optical microscope, though their presence can be confirmed with the use of an ultra microscope or an electron microscope. Homogeneous mixtures with a dispersed phase in this size range may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions, or hydrosols. The dispersed-phase particles or droplets are affected largely by the surface chemistry present in the colloid. Some colloids are translucent because of the Tyndall effect, which is the scattering of light by particles in the colloid. Other colloids may be opaque or have a slight color.

Applications and Examples : 

Applications and Examples Black Pearls Gemstones Milky Glass Metal Alloys Milk (emulsified)

Advantages : 

Advantages The most promising advantages of the sol-gel method is the fact that offers the possibility to prepare solids with pre-determined structure by varying the experimental conditions. Solutions containing a large amount of water and/or catalyzed by ammonia lead to non-linear or network colloidal polymers in hydrolysis-poly condensation process that could be converted to bulk gels or powders; Solution with small water content when catalyzed by HCl, lead to linear polymers. Fiber could be easily drawn from such solution immediately before gelation or films could be deposited.

Disadvantages : 

Disadvantages High cost of raw materials Large shrinkage during processing Residual fine pores Residual hydroxyl Residual carbon Health hazard of organic solution Long processing time

Pictures on Solid Sol : 

Pictures on Solid Sol Black Pearls Gemstones

Slide 9: 

Milky Glass Metal Alloys

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The End Rashika Singh IX C

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