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Evaporating Hydrate Crystals
2/18/2004
name Gunda
status student
age 15
Question - I was wondering how one would know when all the water in a crystal (made of an
anhydrate + water) has been evaporated.
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There are many ways to determine if a solid contains any residual water by infrared
spectroscopy which gives a characteristic "finger print" of water. However, the way that
is commonly done in the lab is to heat the substance to an elevated temperature and measure
the weight loss. When the substance reaches a constant weight it is generally assumed that
all the water has evaporated, but obviously there could be cases where that criterion is
misleading.
Vince Calder
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By checking for weight loss when you subject it to conditions known to drive the water out of
the crystal.
Greg Bradburn
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