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#Post#: 2263--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 8, 2013, 12:19 pm
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Well, the order is quite important here. Because, Barium
chloride gives precipitate with phosphates too. Lead nitrate
gives precipitate with both chlorides and sulfates as they are
insoluble in water. If you do not have bromides or fluorides,
you can use concentrated sulfuric acid for detecting anions
without any hesitation (but drop by drop by using dropper). If
nothing happen with concentrated sulfuric acid, it could be
either phosphate or sulfate. (OR) Please tell me the list of
cations and anions they will provide you for practicals. I'll
tell you a much easier way :)
Shiva
#Post#: 2267--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: March 8, 2013, 12:28 pm
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I encountered many easy ways for some cations and anions, but
the problem is that I have a list of reagents that will be
available, so this eliminated majority of those ways.
Now I looked at the list again, and encountered another problem.
I won't be able to use Pb(NO3)2. Is there another way to
distinguish between acetate and chloride (aside the odor of the
acetates)?
By the way, here is the list:
-Cations:
Ag+,Pb2+,Cu2+,Hg2+,Sn2+,Al3+,Fe3+,Mn2+,Zn2+,Ba2+,Ca2+,Mg2+,Na+,K+,NH4+.
-Anions: Cl-,SO42-,CO32-,NO3-,PO43-,CH3COO-.
#Post#: 2268--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 8, 2013, 12:34 pm
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Okay, now tell me the list of reagents that you are allowed to
use.
#Post#: 2270--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: March 8, 2013, 12:50 pm
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Sorry, this took a while:
-HCl, HNO3 and H2SO4, all concentrated.
-HCl, HNO3, H2SO4, CH3COOH and tartaric acid, all diluted.
-NH3 concentrated.
-NH3 and NaOH diluted.
-Solutions of: (NH4)2CO3, NH4Cl, Na2CO3, (NH4)2S, CH3COONa,
Na2HPO4, K2Cr2O7, BaCl2, K4[Fe(CN)6], SnCl2, Co(NO3)2,
(NH4)2C2O4, HgCl2, KI, KSCN, AgNO3, H2S, Ba(OH)2, CaO.
-Solids and others: (NH4)2MoO4, Nessler, FeSO4, KHSO4, litmus
paper, cobalt glass, introducer of CO2, PbO2, methyl-orange and
platinum wire.
A burner should be present, too.
#Post#: 2271--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 8, 2013, 12:52 pm
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haha omg! too many reagents. There you got concentrated sulfuric
acid, okay I need to write an essay now, giggles :)
#Post#: 2272--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: March 8, 2013, 12:55 pm
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No need to do all that work. You helped me already so much. I
would just need answers to few more questions.
#Post#: 2273--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 8, 2013, 1:05 pm
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Oh you are very welcome :) I'm very glad to help you. I never
been provided with so many reagents for my practicals lol. You
need not to do use all these. I will solve all these for you in
few steps.
Shiva
#Post#: 2274--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 9, 2013, 5:14 am
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Okay, I sorted out this for you. Here you go:
Anion detection:
With concentrated sulfuric acid:
1. CARBONATES: Brisk effervescence (Carbon dioxide)
2. CHLORIDES: Dense pungent smelling fumes (hydrogen chloride)
3. NITRATES: Alkali metal nitrates readily liberate nitrogen
dioxide when they come in contact with concentrated sulfuric and
rest only fume. But, PLEASE DO NOT HEAT THE MIXTURE AS NITRIC
ACID VAPOR IS EXTREMELY CORROSIVE. IN THAT CASE, YOU CAN HEAT
THE NITRATE SAMPLE WITH CONCENTRATED HYDROCHLORIC ACID AND IT
WILL LIBERATE NITROGEN DIOXIDE WITH ALL NITRATES ON HEATING.
4. ACETATES: Fumes and you can perceive the strong odor of
acetic acid.
With Cobaltous nitrate & Silver nitrate solution:
Phosphates give blue precipitate with Cobalt nitrate solution
and yellow precipitation with aqueous Silver nitrate (Distinct
from other anions)
With Barium chloride solution
Sulfates give white precipitate with Barium chloride solution
whereas acetates will not give any and also it gives white
precipitate with Silver nitrate(If you are unsure about acetates
with the above reactions)
Okay, now you know what anion you have been provided with. Next,
Cation detection:
CATION DETECTION:
Appearance:
1. Ferrous - Green
2. Ferric - Brown, Yellow & Red
3. Copper - Blue & Green (Copper chloride)
4. Manganese - Pink
With hydrogen sulfide solution:
1. Black precipitate - Silver, Lead, Copper & Mercuric ions
2. Brown precipitate - Tin & Manganese
3. White precipitate - Zinc
With Sodium carbonate solution:
Aluminium salts give effervescence with Sodium carbonate
solution (distinct from other cations) due to the formation of
Aluminium carbonate which readily decomposes into Carbon dioxide
and Aluminium oxide
If none of the above happens, add Sodium hydroxide solution:
Barium, Calcium & Magnesium give white precipitate with NaOH
whereas Sodium, Potassium & Ammonium ions do not.
If you get white precipitate, you can go ahead and do flame test
for alkaline earths.
The aformentioned reagents will cut off many steps and help you
in proceeding to the confirmation test straightaway. Also, these
reagents are quite efficient in cation detection and save your
time in practicals and of course will lead you to success
undoubtedly :) I hope this is clear. If not, please let me know.
Also, please do not hesitate to ask if there are any questions.
Shiva
#Post#: 2276--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Chemist@
Date: March 9, 2013, 6:43 am
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Thanks very much!
I will have to detect the cation first, because it could mask
the determination of the anion.
"Aluminium salts give effervescence with Sodium carbonate
solution (distinct from other cations) due to the formation of
Aluminium carbonate which readily decomposes into Carbon dioxide
and Aluminium oxide"
I suppose that I will see bubbles because CO2 is formed, so this
is a great reaction, as aluminium could otherwise be a problem.
Going to analyze this deeper now.
I hope that I do this right when the moment comes.
#Post#: 2277--------------------------------------------------
Re: Inorganic qualitative analisys of cations test
DIR By: Shiva
Date: March 9, 2013, 8:30 am
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Yep, you are very welcome :)
This is how Aluminium salts react with Sodium carbonate
solution:
HTML http://www.youtube.com/watch?v=BvxMlWajekk
Shiva
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