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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: gloinddark on November 17, 2009, 11:07:16 AM

Title: preparation of potassium tetracyanonickelate(II) hydrate
Post by: gloinddark on November 17, 2009, 11:07:16 AM

I am writing a report for an experiment for the preparation of potassium tetracyanonickelate(II) hydrate.
the procedure started by:
dissolving 8g of nickel(II) sulfate in 25ml of water. Then 4g of KCN in 10ml of water were added. Now this gave a sky blue precipitate. I didn't find any information about this 'intermediate'.
Then, 4g of KCN in 8ml water were added to this precipitate, and the final required product was obtained.  It is yellow coloured, and known to have a square planar structure.

Does anyone have any idea what the sky blue precipitate may be? My first thought was that it may be the octahedral form of the product, IE hexacyanonickelate(II) but apparently it doesn't even exist.

 :)

Title: Re: preparation of potassium tetracyanonickelate(II) hydrate
Post by: BluRay on November 17, 2009, 02:35:04 PM

Could it be Ni(CN)₂.nH₂O?
Here it says that this compound is blue-green:
http://wwwchem.uwimona.edu.jm/courses/nickel.html

Quote

Ni²⁺ reacts with CN^- to give Ni(CN)₂.nH₂O (blue-green) which on heating at 180-200°C is dehydrated to yield Ni(CN)₂. Reaction with excess KCN gives K₂Ni(CN)₄.H₂O (orange crystals) which can be dehydrated at 100°C. Addition of strong concentrations of KCN produces red solutions of Ni(CN)₅^3-.

Title: Re: preparation of potassium tetracyanonickelate(II) hydrate
Post by: gloinddark on November 17, 2009, 03:22:16 PM

i think you just solved my problem :)
the descriptions match my observations...
thanks!

Title: Re: preparation of potassium tetracyanonickelate(II) hydrate
Post by: BluRay on November 18, 2009, 01:08:01 PM

You're welcome! Glad to have been of help.

Title: Re: preparation of potassium tetracyanonickelate(II) hydrate
Post by: blackp1tth on December 07, 2011, 07:40:15 PM

Hi.. gloinddark

in my time googling tetracyanonickleat, your posting came out.
and so did I, on the process to prepare K2[Ni(CN)4] ...
i need to asking/discuss one-two things about it ...

can you help me !?