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Author: Subject: Name for frozen phases
chornedsnorkack
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[*] posted on 19-5-2020 at 11:18
Name for frozen phases


If you freeze a solid out of a solution, and the solid contains water and something else, it is a "hydrate".

Is there any term for solids that have a fixed composition, maximum of melting point, but none of the components is water?
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[*] posted on 19-5-2020 at 12:56


Solvates.
But beware that , like "hydrates" it's a verb as well as a noun.
Words like Etherates and alcoholates get used. Their status is a bit questionable.
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[*] posted on 19-5-2020 at 13:05


Solvates are also sometimes coordination complexes.



Please remember: "Filtrate" is not a verb.
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[*] posted on 19-5-2020 at 14:14


Quote: Originally posted by DraconicAcid  
Solvates are also sometimes coordination complexes.

And hydrates aren't?
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[*] posted on 19-5-2020 at 18:16


Quote: Originally posted by j_sum1  
Quote: Originally posted by DraconicAcid  
Solvates are also sometimes coordination complexes.

And hydrates aren't?


Some are, some aren't. Even in some coordination compounds, some of the water is coordinated to the transition metal centre, while other water molecules are simply stuck in the lattice.




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chornedsnorkack
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[*] posted on 19-5-2020 at 21:57


Does "solvate" require you are specifying one but not the other components as "the solvent"?

The system H2O-SO3 is miscible in all ratios above melting point (note that it sublimes near the SO3 end).

The maximum melting point compositions are customarily, with some evidence, designated:
  1. H2O
  2. H2SO4*4H2O
  3. H2SO4*2H2O
  4. H2SO4*H2O
  5. H2SO4
  6. H2S2O7
  7. SO3

Note that customarily with evidence, it is H2SO4*2H2O, not H6SO6, yet H2S2O7, not H2SO4*SO3
For system H2O-N2O5, I have seen phase curve between H2O and HNO3, but not the part between HNO3 and N2O5.

Are there any solid phases in system H2O-SO3-N2O5 that you would write as several molecules not including water?
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[*] posted on 19-5-2020 at 22:58


Quote: Originally posted by DraconicAcid  
Quote: Originally posted by j_sum1  
Quote: Originally posted by DraconicAcid  
Solvates are also sometimes coordination complexes.

And hydrates aren't?


Some are, some aren't. Even in some coordination compounds, some of the water is coordinated to the transition metal centre, while other water molecules are simply stuck in the lattice.

That was kind of my point. Some.
I remember being informed by woelen that it was possible (common) to produce crystals of complexes. I had previously only associated complex ions with solutions, and while I was aware of hydrates, I did not associate them with any kind of complexing.
And of course, the situation is even more complex than that (pun intended). The water or other solvent may be complexed or it may simply be trapped in defined stoichiometric ratios in the interstices of the crystal lattice.
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[*] posted on 20-5-2020 at 01:32


Quote: Originally posted by chornedsnorkack  


Are there any solid phases in system H2O-SO3-N2O5 that you would write as several molecules not including water?

Does H3O+ HSO4- count?
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