Английский язык: english for masters of chemistry
Sol is a colloidal suspension with solid particles in a liquid. 2. Emulsion
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- Dispersion Medium Dispersed Phase Type of Colloid Example
- Dialysis
| Sol is a colloidal suspension with solid particles in a liquid.
2. Emulsion is between two liquids. 3. Foam is formed when many gas particles are trapped in a liquid or solid. 4. Aerosol contains small particles of liquid or solid dispersed in a gas. When the dispersion medium is water, the colloidal system is referred to as a hydrocolloid. The particles in the dispersed phase can take place in different phases depending on how much water is available. For example, Jell-O powder mixed in with water creates a hydrocolloid. A common use for hydrocolloids is in the creation of medical dressings. (Jell-O is a brand name belonging to Illinois-based Kraft Foods for varieties of gelatin desserts, including fruit gels, puddings and no-bake cream pies. The brand's popularity led to "jello" becoming a generic term for gelatin dessert across the U.S. and Canada). 59 ______________________ ______________________ ______________________ ________________ _______________________ _______________________ _______________________ _______________________ _____________ Dispersion Medium Dispersed Phase Type of Colloid Example Solid Solid Solid sol Ruby glass Solid Liquid Solid emulsion/gel Pearl, cheese Solid Gas Solid foam Lava, pumice Liquid Solid Sol Paints, cell fluids Liquid Liquid Emulsion Milk, oil in water Liquid Gas Foam Soap suds, whipped cream Gas Solid Aerosol Smoke Gas Liquid Aerosol Fog, mist An easy way of determining whether a mixture is colloidal or not is through use of the Tyndall Effect. When light is shined through a true solution, the light passes cleanly through the solution, however when light is passed through a colloidal solution, the substance in the dispersed phases scatters the light in all directions, making it readily seen. An example of this is shining a flashlight into fog. The beam of light can be easily seen because the fog is a colloid. Figure: Light being shined through water and milk. The light is not reflected when passing through the water because it is not a colloid. It is however reflected in all directions when it passes through the milk, which is colloidal. Another method of determining whether a mixture is a colloid is by passing it through a semipermeable membrane. The larger dispersed particles in a colloid would be unable to pass through the membrane, while the surrounding liquid molecules can. Dialysis takes advantage of the fact that colloids cannot diffuse through semipermeable membranes to filter them out of a medium. Preparation. There are two principal ways of preparation of colloids: Dispersion of large particles or droplets to the colloidal dimensions by milling, жүктеу/скачать 4.51 Mb. Достарыңызбен бөлісу:
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