Wednesday, February 1, 2012

A bottle containing solid iodine crystals fills with a violet haze upon standing at room temperature.?

What is the violet haze and why does it form?

A bottle containing solid iodine crystals fills with a violet haze upon standing at room temperature.?
It is iodine vapor. The vapor pressure of solid iodine at 30 degrees C is about 0.47 torr = 6.2*10^-4 atm. Gaseous molecular iodine (I2) strongly absorbs longer-wavelength (i.e., red) visible light, so the vapor looks violet. Even the small amount of I2 gas corresponding to this partial pressure is enough to be visible.


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