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#Post#: 2115--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 14, 2013, 11:59 am
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Okay, thanks anyway.
#Post#: 2130--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 19, 2013, 9:05 am
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If I add ammonia to magnesium and barium, will a precipitate
form?
#Post#: 2131--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: February 19, 2013, 9:26 am
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Yep with Magnesium ion but it will not give any precipitate with
Barium ion as Baryta (Barium hydroxide) is soluble in water.
Shiva
#Post#: 2132--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 19, 2013, 9:30 am
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Thanks. So, only Ca and Mg will make a precipitate from the
earth-alkali metals (Be is not in my interest). Can the
precipitates easily be seen?
I found a picture of the precipitate of SnS in neutral
solutions. It is brown. Also the solution isn't clear, as you
said.
#Post#: 2133--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: February 19, 2013, 9:40 am
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Yep and Strontium ion will give precipitate too with Ammonium
hydroxide. Be2+ will give too but Beryllium compounds are quite
expensive, extremely toxic and carcinogenic. Only big
laboratories do hold Beryllium compounds.
As far as Stannous sulfide is concerned, yeah it is brown and
Stannic sulfide is yellow. Yes it is not clear like you said.
#Post#: 2134--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 19, 2013, 11:02 am
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Can the precipitate, formed when ammonia is added to Ca2+ or
Mg2+, be easily seen (the hydroxides)?
#Post#: 2135--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: February 20, 2013, 3:08 am
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This will explain you :)
HTML http://www.youtube.com/watch?v=cz_O7oO7Ufg
#Post#: 2139--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 20, 2013, 9:34 am
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Very nice video. Sadly, both calcium and magnesium, as I saw,
are hardly noticed when precipitated with ammonia. Thanks very
much.
How could I determine Sn2+ ions in a solution except
precipitating it with sulfide?
Sorry for asking so many questions, but I need to do this
perfectly. I still have much time, but I want to make a perfect
chart as soon as possible.
#Post#: 2140--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: February 20, 2013, 10:06 am
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Not a problem at all :) Well, in this video, you can clearly see
the precipitate of Magnesium hydroxide. However, in the case of
Ca2+, the precipitation will appear little slower, will take a
minute or so to precipitate calcium hydroxide. As far as
detecting stannous ion is concerned, it can also be detected by
adding Mercuric chloride. First, it will give a white
precipitate of Mercurous chloride and it further reduced to
metallic mercury on gentle warming. But, this one is too risky
as Mercuric chloride is quite lethal as a poison. Usually, white
of an egg will be given as an antidote for Mercuric chloride
poisoning cases. You can also detect stannous salt by placing
much reactive metal like Magnesium in stannous salt solution and
after a few minutes, you can notice a spongy deposit of tin on
the surface. In my view, precipitating sulfide is a much
convenient method. I've done it a couple of times and it is
quite easy. But, please use strong solution of hydrogen sulfide
as common tin compounds are not very soluble and excessive
hydrogen sulfide will give a clear brown precipitate of Stannous
sulfide. Hope this is helpful. Please let me know if you have
any questions.
Shiva
#Post#: 2141--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: February 20, 2013, 12:18 pm
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Thanks for helping me so much. I am going to reconsider
everything and probably make a new chart.
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