PIRA 6F40.10 Scattering Sunset
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Photo of the Demonstration at the University of Texas
Instructions / Notes:
A light beam is projected through a 4 liter beaker atop of an overhead
Demo Staff: The beaker sits atop of a black piece of cardboard
with a hole cut out of it.
The beaker contains a sodium thiosulfate solution. A separate 125 ml flask
contains a sulfuric acid solution.
Sodium Thiosulfate Solution: 20 grams of Na2S2O3
dissolved into 4 liter beaker of H2O.
Mix the sodium thiosulfate solution on the preceding day or very early
in the morning.
Sulfuric Acid: 1mL of H2SO4 is added
to 124mL H2O in a separate flask before the class.
During class the sulfuric acid solution in the flask is mixed with the sodium thiosulfate
Briefly stir the sulfuric acid in the tank, turn on the lamp and wait four
to five minutes.
A sulfate precipate begins to cloud the tank causing the first scattering
effect, which appears nearly sky-blue within the tank.
The projected light seen on the opposite wall at this point changes from
white to yellow.
The next phase, which occurs very briefly, two scattering colors are noticed
in the tank, while the light projected on the wall becomes orange.
When the light projected on the wall appears to be red, the chemical reaction
Last Updated 11/2000 - University of Texas at Austin
Physics Department - All Rights Reserved