RAYLEIGH SCATTERING
Why the Sky Is Blue and Sunsets are Red?
(This demonstration is no longer done.)
EQUIPMENT
5
L Plastic Water Tank
18 g of
Sodium Thiosulfate (hypo)
10 ml of HCl
5 L of Distilled Water
Lamp
NARRATIVE
The sky is blue and some sunsets are red because
of Rayleigh Scattering of light from particles about the size of a wavelength of light.
Before class, dissolve 18 g of hypo in 5 L of distilled water. (The solution will be
cloudy). At or a little before the demonstration is to be done, stir in 10 ml of HCL. This
will clear the solution. Precipitation of sulfur will begin anywhere from 30 sec to 3
minutes. Precipitation is essentially complete 2 to 5 minutes after it begins.