Akhil jain
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Practical chemistry
I have studied that if we use NH4Cl and NH4OH(group 3 reagent)then due to common ion effect the concentration of OH- ions is so lowered that only
(group 3 ions ) Al+++ ,Fe+++,Cr+++ ions get precipitated as hydroxides and ( group 4 ions) Ni++,Zn++,Co++ ,Mn++,Fe++ remain in solution because group
3 ion hydroxides have less solubility product that of group 4. But when I did it in my home lab group 4 ions also get precipitated with group 3 when I
added group 3 reagent - NH4Cl and NH4OH.
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woelen
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What are groups 3 and 4? According to what classification?
With ammonia in solution, regardless of the presence of additional ammonium ions, I would expect precipitation of all of these ions. If you add a lot
of ammonia, I expect the Ni(2+) to go in solution again as a bright blue complex [Ni(NH3)6](2+). Co(2+) also will form a coordination complex.
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Boffis
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In Vogel's text book he calls them Group IIIA and Group IIIB and basically you need a significant excess of the reagent. In the course of systematic
analysis the ammonium chloride is generated in-situ by the addition of excess 5M ammonia solution over that required to neutralize the hydrochloric
acid used to expel the excess sulphides from the previous Group II isolation. If you are going to add the ammonium chloride as a solution of this salt
(presumably therefore you have skipped the isolation of Groups I an II) you will need to go through the procedure and estimate the approximate
concentration of NH4Cl generated and then add it as a fairly strong solution before adding the ammonia.
What exactly are you doing? I would help us to answer your question better if you give us more details of what you have already done to the solutions.
Which textbook or scheme are you using?
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Akhil jain
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See my channel akhil the chemist I have uploaded a lot of videos of practical chemistry . You may understand
What I have done to solutions.i have not uploaded any test for group 4 cations but group 3 - aluminium and Ferric ions test I have uploaded .
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Akhil jain
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Actually I wanted to make sodium chromate from stainless steel . I dont want to ppt Ferrous hydroxide along with chromium hydroxide ferrous hydroxide
has a higher solubility product than Chromium hydroxide if those experiments were successful it would be very easy to make sodium chromate
[Edited on 23-2-2018 by Akhil jain]
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alirezaghaieby
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hi
i boiled water to remove oxygen, then i dissolved Fe.SO4.7H2O and obtained a pale brown (hazzy) solution. after adding stoichiometric amounts of
glycine and citric acid i obtained a green solution. to get the residue i put the bea;er on a fanquel but every time i use citric acid i get an oiy
precipipate. what is the cause and hou can i solve this problem? i want to get a crystal.
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RawWork
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Where's your channel? We won't search for it. You know how to post url?
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Boffis
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@Akhil Jain, If you have the metals (Cr Fe etc) in sulphuric acid solution you can simply boil it and then precipitate the other metals with excess
NaOH. This works because the Cr forms a kinetically stable sulphato complex that precipitates with NaOH only very slowly. So you simply allow the
precipitated hydoxides to settle, decant or filter of the clear sea blue green sulphatochrome complex and then leave it to stand. After a few days the
blue hydroxide/basic sulphate with start to precipitate in an easy to filter granular form, complete precipitation can take a month but you can boil
the alkaline solution to accelerate the process but the ppt is less granular. You can then use this material to make you sodium chromate by what ever
means you intend to use.
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Akhil jain
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Search for my channel akhil the chemist . You will get it on top just search akhil the the chemist on YouTube
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Ubya
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https://www.youtube.com/channel/UC9GD00yhAoKajgjRWvqyH-w
it's not that hard to put a link you know?
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feel free to correct my grammar, or any mistakes i make
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Akhil jain
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Oh you have searched it . Good how is it any comments
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