Hexavalent
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Calcium Sulfate Hemihydrate
CaSO4-0.5H2O
Can someone please explain how this compound han have half a water molecule as a ligand for water of crystallization?
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Magpie
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This represents a ratio of molecules in the crystal, ie, there is one molecule of water for every two molecules of CaSO4.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Megak
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These numbers are simply molar ratios and are used to make life easier for measuring and theorizing equations. The mole, represents 6.022 x 10^24
representative particles (I think, but you can always look up Avagadro's number). So when there is 1 mole of a substance, you actuallyhave trillions
and trillions of actual molecules or formula units.
I hope this answers your question!
[Edited on 9-1-2012 by Megak]
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ScienceSquirrel
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Quote: Originally posted by Hexavalent  | CaSO4-0.5H2O
Can someone please explain how this compound han have half a water molecule as a ligand for water of crystallization? |
It is 2CaSO4-1H2O, where approximately one molecule of water is shared between two calcium ions and two sulphate ions.
The ratio is not exact and varies between samples.
http://en.wikipedia.org/wiki/Calcium_sulfate#Dehydration_rea...
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bob800
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What would happen if, hypothetically, a single molecule was isolated?
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ScienceSquirrel
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There is no such thing as a single molecule in this case. It is a lattice built of calcium and sulphate ions with water molecules shared between them.
Not all substances have exact formulas, some are approximations.
[Edited on 9-1-2012 by ScienceSquirrel]
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