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Author: Subject: Cu, Ni and Mn selenites + photo
vano.kavt
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[*] posted on 4-12-2020 at 03:05
Cu, Ni and Mn selenites + photo


I made some selenites. First one is copper selenite dihydrate CuSeO3·2H2O. It is very nice blue powder or crystal, but i never seen crystal. It's insoluble in water.

I made it from basic copper carbonate and selenous acid:

Cu2(OH)2 CO3 + 2H2SeO3 → 2CuSeO3 + ......

Second one is nickel selenite dihydrate and NiSeO3·2H2O. It's light green insoluble powder. But i think this selenite is much soluble than copper selenite, because when water added it becomes like a suspension, which is yellow liquid.

I used nickel chloride hexahydrate and sodium selenite:

NiCl2 + Na2SeO3 → NiSeO3 + 2NaCl

Third one is manganese selenite • ?H2O. Its brown insoluble solid. I do not have much information about it. It is a rather rare compound because I did not even know the color before I made it.

I used manganese carbonate and selenous acid:
MnCO3 + H2SeO3 →MnSeO3 + H2O + CO2


received_396742351443054.jpeg - 508kB

[Edited on 4-12-2020 by vano.kavt]
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Bedlasky
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[*] posted on 4-12-2020 at 04:58


Hi and welcome to SM :).

These selenites have beautiful colour, especially nickel selenite.

Colour of manganese selenite is weird for II oxidation state. It looks like some Mn(III) or Mn(IV) compound. How precipitate looked when it was freshly made? Was there red precipitate mixed with brown precipitate? Mn(II) compounds are mostly only weakly coloured. There are some exceptions like MnO or tetraamonium hexamolybdatomanganate(II), but brown colour in 99% have compounds of trivalent and tetravalent manganese.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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vano.kavt
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[*] posted on 4-12-2020 at 05:23


Quote: Originally posted by Bedlasky  
Hi and welcome to SM :).

These selenites have beautiful colour, especially nickel selenite.

Colour of manganese selenite is weird for II oxidation state. It looks like some Mn(III) or Mn(IV) compound. How precipitate looked when it was freshly made? Was there red precipitate mixed with brown precipitate? Mn(II) compounds are mostly only weakly coloured. There are some exceptions like MnO or tetraamonium hexamolybdatomanganate(II), but brown colour in 99% have compounds of trivalent and tetravalent manganese.


Thank you. Yes i know its Strange. I use manganese carbonate, which i bought in my town and i'm 100% sure that it is Chemically pure compound. As for the selenic acid it is the same. I did all the compounds in one day. I have no information. I tried English, Georgian, Russian and other languages, but to no avail.

[Edited on 4-12-2020 by vano.kavt]
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