The Tyndall Effect

For troubleshooting suspected foam problems, vaporize samples of feed and bottoms to look for suspended solids. Also, one can look for the Tyndall effect as described in the section on condenser fogging. 

A colloid fog will scatter a beam of light. This is called the Tyndall Effect and can be used as a troubleshooting tool. 

Airborne particulates include dust, fume and aerosols. Many such particles are invisible to the naked eye under normal lighting but are rendered visible, by reflection, when illuminated with a strong beam of light. This is the Tyndall effect and use of a dust lamp provides a simple technique for the rapid assessment of whether a dust is present, its flow pattern, leak sources, the effects of ventilation, etc. More sophisticated approaches are needed for quantitative data. Whether personal, spot or static sampling is adopted will depend upon the nature of the information required. 

Colloids will reflect or scatter light while true solutions do not this is known as the Tyndall effect. 

After these first explanations and discussions, the students were shown some experiments. The explanations were diverse Some students explained the swelhng of SAP as a chemical reaction, not as an uptake of water between the polymer strac-tures. The demonstration of the Tyndall effect was also not helpful to evaluate the two theories in a better way, as both were used again as explanations. 

A Na2C03 is the only solute that exhibits the Tyndall effect. 

An instrument used to observe particles too small to be seen by the ordinary light microscope. The ultramicroscope makes use of the Tyndall effect. Ultrasonics... 

But the microscopic fat particles suspended in milk have an average diameter in the range 10-7 to 10-5 m, i.e. much larger than k of visible light. A beam of incident light is scattered rather than transmitted by a suspension of particles - a phenomenon known as the Tyndall effect. 

The study of the scattering of light by colloidal systems has a long history. The Tyndall effect describes the scattering of light by suspended particles. In fact, the first rigorous theory was that of Rayleigh in 1871. 

Chicken broth is cloudy because it is colloidal, containing microscopic particles of chicken fat suspended in the water-based soup. Like milk, cream or emulsion paint, the cloudy aspect of the soup is a manifestation of the Tyndall effect. Adding the eggshells to the colloidal solution removes these particles of fat, thereby removing the dispersed medium. And without the dispersed medium, the colloid is lost, and the soup no longer shows its cloudy appearance. We say we have broken the colloid. 

The hand cream is opaque as a consequence of the Tyndall effect. 

Blue skies and the Tyndall effect by M. Kerker in/. Chem. Educ., 1971, 48, 389 is a nice introduction. Alternatively, try Chapter 7 Some important properties of colloids II scattering of radiation in Everett (above), which is extremely thorough. 

Colligative properties are those properties of solutions that depend on the number of solute particles present and not their identity. Colligative properties include vapor pressure lowering, freezing point depression, boiling point elevation, and osmotic pressure. Colloids are homogeneous mixtures, in which the solute particles are intermediate in size between suspensions and true solutions. We can distinguish colloids from true solutions by the Tyndall effect. 

The simplest way to distinguish a colloid from a solution is a. the Tyndall effect b. the osmotic pressure... 

A colloid is a mixture in which the solute particle size is intermediate between a true solution and a suspension. If a light is shone through a colloid, the light beam is visible. This is the Tyndall effect. 

Tyndall effect The Tyndall effect is exhibited when a light is shone through a colloid and is visible, owing to the reflection of the light off the larger colloid particles. 

The solution is transformed to an oil-in-oil emulsion in which a polystyrene solution forms the disperse phase and the elastomer polyester component solution the continuous phase. The point of phase separation is observed experimentally by the onset of turbidity, due to the Tyndall effect. The conversion required for phase separation to occur depends basically on the solubility of the polystyrene chains in the elastomer solution, which in turn is governed by the elastomer concentration and compatibility of the two polymers. 

To detect the Tyndall effect, use a device (Fig. 108) consisting of a box divided into two equal parts by partition 1 with small aperture 2 at its middle. An electric lamp (100-150 W) is installed in outer wall 3 of the box. The second half of the box is provided with shelf 4 on which a beaker with a solution is placed. Observations are performed through an opening in the box door. 

Figure 7.4—Light diffusion detector. Using nitrogen gas, the mobile phase is nebulised at the end of the column with a device of varying geometry. When a compound elutes from the column, the droplets under evaporation are transformed into fine particles that can diffuse light from a laser. This is called the Tyndall effect (it is similar to what is observed for a car when its lights are diffused by fog). The signal, detected by a photodiode, is proportional to the concentration of the compound. This detector can only be used for compounds that cannot be vaporised into the gas phase in the heated zone.

Some samples of natural origin contain micellar particles in suspension that cause, by light scattering (the Tyndall effect), a supplementary absorbance that varies with wavelength. 

Solutions of cellulose derivatives, such as nitrocellulose, passed through a fine porous filter demonstrate neither the Tyndall effect, nor the presence of particles visible in the ultra-microscope. This is one more piece of evidence that the properties of these solutions are the same as those of substances with low molecular weight. The same holds for cellulose in ammoniacal solutions of cupric oxide ( cupr-ammonium ). 

A solution is a homogeneous mixture that has one or more solutes dispersed at a molecular or ionic level throughout a medium called the solvent. The dispersed phase in a colloid is much larger than a typical molecule. For this reason, colloids exhibit the Tyndall effect, or the ability to trace out a ray of light shown through the colloid. 

While individual dispersed particles are not visible, the suspensions can scatter light (the Tyndall effect). 

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