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woelen
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Most likely the green stuff is not Cr2(SO4)3.xH2O, but a basic chromium sulfate. Basic chromium sulfate is green and its solutions also are green.
When a small amount of H2SO4 or HNO3 is added and allowed to stand for a few days, then the solution turns purplish/grey.
Basic chromium sulfate is present on eBay:
http://www.ebay.nl/itm/1kg-Chromium-Sulphate-top-quality-/22...
The formula on the bottle is wrong. In reality it best can be written as:
[Cr(OH)2]Cr(SO4)2 or as [Cr(OH)]2(SO4)2 or simply [Cr(OH)]SO4
It also sometimes is written as: [CrO]Cr(SO4)2.H2O
Solotions of this compound contain the green [Cr(OH)](2+) ion, the green [Cr(OH)2](+) ion and green sulfato-chromium(III) complexes.
The commercial product usually contains one sodium ion besides each chromium ion (due to how it is made) and then the net formula is
[Cr(OH)2]Cr(SO4)2.Na2SO4 or [Cr(OH)]2(SO4)2.Na2SO4
Also written as: [CrO]Cr(SO4)2.Na2SO4.H2O
Separation from the sodium sulfate is difficult and for its application it does not really matter, so the commercial product nearly always is the one
with the sodium sulfate in it.
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TheMrbunGee
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Quote: Originally posted by woelen  | Most likely the green stuff is not Cr2(SO4)3.xH2O, but a basic chromium sulfate. Basic chromium sulfate is green and its solutions also are green.
When a small amount of H2SO4 or HNO3 is added and allowed to stand for a few days, then the solution turns purplish/grey.
Basic chromium sulfate is present on eBay:
http://www.ebay.nl/itm/1kg-Chromium-Sulphate-top-quality-/22...
The formula on the bottle is wrong. In reality it best can be written as:
[Cr(OH)2]Cr(SO4)2 or as [Cr(OH)]2(SO4)2 or simply [Cr(OH)]SO4
It also sometimes is written as: [CrO]Cr(SO4)2.H2O
Solotions of this compound contain the green [Cr(OH)](2+) ion, the green [Cr(OH)2](+) ion and green sulfato-chromium(III) complexes.
The commercial product usually contains one sodium ion besides each chromium ion (due to how it is made) and then the net formula is
[Cr(OH)2]Cr(SO4)2.Na2SO4 or [Cr(OH)]2(SO4)2.Na2SO4
Also written as: [CrO]Cr(SO4)2.Na2SO4.H2O
Separation from the sodium sulfate is difficult and for its application it does not really matter, so the commercial product nearly always is the one
with the sodium sulfate in it. |
ok, I added H2SO4 to the solution, left it to stay, lets check this theorry.
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The Volatile Chemist
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With regards to the magnesium sulfate, you could always give it to a school or something, they always have use for the stuff in high schools. And if
the compound of the year for the US Crystal growing competition is magnesium sulfate, well there you go...
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TheMrbunGee
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| Quote: Originally posted by The Volatile Chemist | | With regards to the magnesium sulfate, you could always give it to a school or something, they always have use for the stuff in high schools. And if
the compound of the year for the US Crystal growing competition is magnesium sulfate, well there you go... |
I am from Latvia, I never heard that that schools here accept chemicals for lab.. and also I am not sure about purity.. crystal growing is not popular
either. :/
I left few kilos for crystal growing for myself..
| Quote: |
Most likely the green stuff is not Cr2(SO4)3.xH2O, but a basic chromium sulfate. Basic chromium sulfate is green and its solutions also are green.
When a small amount of H2SO4 or HNO3 is added and allowed to stand for a few days, then the solution turns purplish/grey.
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9 days later - solution with acid is still green!
[Edited on 17-8-2016 by TheMrbunGee]
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