Chemistry Reference
In-Depth Information
Air
Thin Liquid Film
Air
FIGure 8.1
Formation of a bubble.
TLF
Black Film
FIGure 8.2
TLF and reflection of light.
thickness of the film approaches the dimensions of the wavelength of light, varying
interference colors are observed. The reflected ray will interfere with the incident
wavelength. The consequence of this will be that, depending on the thickness of the
film, one will observe colors, especially when the thickness of the film is approxi-
mately the same as the wavelength of the light (i.e., 400-1000 Å). The black film
is observed when the thickness is the same as the wavelength of the light (approxi-
mately 500-700 Å). Thus, this provides the closest visual observation of two-mole-
cule thick film by eyesight.
8.2.1 a
p p l I c aT I of n
of f
b
u b b l e S
I n
T
e c h n of l of g y
Bubbles are critical in manufacturing in the food industry. The stability and size
of the bubbles determines the taste and the looks of the product. In industry, much
research has been done on the factors that control bubble formation and stability.
This is of special interest in the production of ice cream, where air bubbles are
trapped in frozen material.
8.3 FoamS (thIn lIquId FIlmS)
Ordinary foams from detergent solutions are initially thick (measured in microme-
ters), and, as the fluid flows away, due to gravity or capillary forces or surface evapo-
ration, the film becomes thinner (by a few hundred angstroms).
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