Sciencemadness Discussion Board

Crystal solvents

chornedsnorkack - 5-1-2014 at 02:16

What is the term for crystal salts containing solvents other than water? Crystals with water of crystallization are named hydrates, but other salts?

For example, metals have sulphates (ion (SO4)2-) and hydrogen sulphates (ion HSO4-), but how are crystal salts called that contain sulphuric acid beyond HSO4- ions?

The solubilities of metals in 100 % sulphuric acid are funny. While alkali metal sulphates are soluble in both water and concentrated sulphuric acid, most other metals have contrasting behaviour.
A number of sulphates that are very soluble in water are very poorly soluble in concentrated sulphuric acid - these include MgSO4, ZnSO4, CuSO4, FeSO4, NiSO4 and Al2(SO4)3. In contrast, several sulphates that are poorly soluble or insoluble in water dissolve well in sulphuric acid - these include Ag2SO4, CaSO4, BaSO4.
For example, the soluble barium salt is
Ba(HSO4)2*2H2SO4
How would you call it?

bfesser - 5-1-2014 at 06:16

<a href="http://en.wikipedia.org/wiki/Double_salt" target="_blank">Double salts</a> <img src="../scipics/_wiki.png" />?

DraconicAcid - 5-1-2014 at 12:18

BaSO4 is barium sulphate.
Ba(HSO4)2 is barium hydrogen sulphate, or to use older nomenclature barium bisulphate (because it has twice as many sulphates per barium as usual).
Ba(HSO4)2*H2SO4 would have three sulphates per barium, so barium trisulphate.

Ba(HSO4)2*2 H2SO4 would be barium tetrasulphate.

This would fall in line with the accepted (though not quite IUPAC) name of potassium tetraoxalate ( http://www.sigmaaldrich.com/catalog/product/fluka/60592?lang... ).

DraconicAcid - 5-1-2014 at 16:53

And the think the thread title should have been "Nonaqueous Solvates"

Come to think of it, the IUPAC name would probably be something like "barium sulphate two sulphuric acid", in the same way that "two water" is now supposed to replace the much more elegant "dihydrate".

[Edited on 6-1-2014 by DraconicAcid]

ScienceSquirrel - 5-1-2014 at 17:34

They can be labelled in as coordinating ligands;

http://en.wikipedia.org/wiki/Tetrakis%28acetonitrile%29coppe...

DraconicAcid - 5-1-2014 at 18:18

Quote: Originally posted by ScienceSquirrel  
They can be labelled in as coordinating ligands;

http://en.wikipedia.org/wiki/Tetrakis%28acetonitrile%29coppe...


That would work for some solvents, but I don't think sulphuric acid is much of a ligand.

turd - 6-1-2014 at 05:37

Quote: Originally posted by chornedsnorkack  
What is the term for crystal salts containing solvents other than water? Crystals with water of crystallization are named hydrates, but other salts?

They are called (quite unsurprisingly) solvates. If you are interested in this topic see also pseudo-polymorphs or solvatomorphs.

Quote:
For example, metals have sulphates (ion (SO4)2-) and hydrogen sulphates (ion HSO4-), but how are crystal salts called that contain sulphuric acid beyond HSO4- ions?

Interestingly, this has nothing to do with the original question, since I don't know anybody who would consider that a solvate. These are acidic hydrous phases of the form (MOt)x.(SO3)y.(H2O)z. And as Draconic Acid noted correctly, RbH5(PO4)2 is simply called rubidium pentahydrogen bisphosphate (or bis(phosphate(V)) if you want to be anal).

Quote:
They can be labelled in as coordinating ligands;

No. This is not coordination chemistry. This is oxidic inorganics.