MeshPL
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Best way of converting salts to Ni(NO3)2and Co(NO3)2
So, soon will be buying some chemicals and will need Ni(NO3)2 and Co(NO3)2. For some reason they are much more expensive than respective chlorides or
sulphates, so I have a question: what is the best way to convert it to nitrate? I was thinking that I should percipitate carbonate or hydroxide, than
filter it and dissolve in HNO3. But, should I go for carbonate or hydroxide? What are the optimal conditions for percipitation? What is the best way
to filter? Gravity filtration is the only option for me, also, should I use regular coffee filters or buy special filtering paper together with
chemicals?
Do you guys have any relevant experiences?
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DFliyerz
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Carbonate is generally a good choice, since it precipitates reliably without any complex forming and can provide a good gauge of whether or not the
reaction is working. Also, at least in my experience, carbonates tend to be easier to filter than hydroxides.
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Oscilllator
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I once precipitated nickel chloride as the carbonate and got a horrible, unfilterable goo because of the conditions I used (cold, concentrated). If
you decide to do this, I suggest precipitating it a little at a time from a nice hot solution to try to maximise particle size.
I also concur with DFliyerz that carbonates are easier to filter than hydroxides.
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MeshPL
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Ok. Thanks.. Would sodium bicarbonate or carbonate work better?
I bet bicarbonate, as it is less likely to percipitate some mixed carbonate-hydroxide compounds.
[Edited on 27-3-2016 by MeshPL]
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blogfast25
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Quote: Originally posted by MeshPL  | Ok. Thanks.. Would sodium bicarbonate or carbonate work better?
I bet bicarbonate, as it is less likely to percipitate some mixed carbonate-hydroxide compounds.
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Co and Ni don't form basic carbonates easily, IIRW. But even if they did, the basic carbonates dissolve easily to nitrates too.
My choice would be carbonate, rather than bicarbonate because that way you don't need to deal with the CO2:
Co2+(aq) + 2 HCO3-(aq) === > CoCO3(s) + CO2(g) + H2O(l)
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BromicAcid
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Do you have any issue with water of hydration? If you need truly anhydrous material sometimes that can be a bit difficult
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MeshPL
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No I don't need carbonates anhydrous nor dry, just quite pure and easy to filter. I wonder whether carbonate or bicarbonate will produce a material
with bigger grain size and thus easier to filter. Carbonate will surely not bubble as much as bicarbonate, but that is not a big deal and considering
I will make carbonate from twice cheaper bicarbonate, I don't know what to use.
[Edited on 27-3-2016 by MeshPL]
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annaandherdad
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I don't know if this will help, but once when trying to precipitate zinc carbonate I got a horrible goo that certainly could not be filtered. It
created a layer about an inch or two thick on top of the filter paper I was using.
I found that if I just let the goo air dry (takes several days), then crush up the dried stuff and put it back into distilled water, the result was
easy to filter and wash. I didn't attempt to wash the goo, there was no point in trying. But after the first drying it was easily filtered and
washed.
Maybe this would work with cobalt and nickel.
Any other SF Bay chemists?
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blogfast25
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| Quote: Originally posted by annaandherdad | I don't know if this will help, but once when trying to precipitate zinc carbonate I got a horrible goo that certainly could not be filtered. It
created a layer about an inch or two thick on top of the filter paper I was using.
I found that if I just let the goo air dry (takes several days), then crush up the dried stuff and put it back into distilled water, the result was
easy to filter and wash. I didn't attempt to wash the goo, there was no point in trying. But after the first drying it was easily filtered and
washed.
Maybe this would work with cobalt and nickel. |
How easy (or hard) a precipitate filters depends a lot how it is produced.
Generally the best results are obtained by precipitation from fairly dilute solutions (typically less than 1 M).
Allowing the precipitate to stand overnight before filtration often also helps the filtering process because it promotes larger crystallites (which
tend to clog the filter less). It also reduces occlusion of impurities (co-precipitated material re-enters solution), giving a purer product.
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