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Topic: precipitimetry  (Read 16653 times)

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Offline AhmedEzatAlzawalaty

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precipitimetry
« on: March 03, 2007, 03:34:34 PM »
why AgCN dissolves AgCl AgBr AgI but not .
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Offline Borek

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Re: precipitimetry
« Reply #1 on: March 03, 2007, 03:46:41 PM »
Try to reword your post, it doesn't make any sense now.
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Offline english

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Re: precipitimetry
« Reply #2 on: March 04, 2007, 03:49:09 PM »
I think he may be asking why AgCN dissolves, but the silver halides do not?
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Offline Borek

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Re: precipitimetry
« Reply #3 on: March 04, 2007, 07:12:51 PM »
Could be.
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Offline AWK

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Re: precipitimetry
« Reply #4 on: March 05, 2007, 08:42:17 AM »
Quote from: ahmedezat on March 03, 2007, 03:34:34 PM
why AgCN dissolves AgCl AgBr AgI but not .
Do you mean KCN?
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Offline english

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Re: precipitimetry
« Reply #5 on: March 06, 2007, 03:11:50 AM »
Quote from: AWK on March 05, 2007, 08:42:17 AM
Quote from: ahmedezat on March 03, 2007, 03:34:34 PM
why AgCN dissolves AgCl AgBr AgI but not .
Do you mean KCN?

Silver cyanide is insoluble?  I don't recall that from anywhere.  Thanks for the refresher.
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Offline Borek

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Re: precipitimetry
« Reply #6 on: March 06, 2007, 04:44:34 AM »
pKso = 15.66

CN- is sometimes called pseudohalide - and for a reason :) Just like SCN-, OCN- and others I am not sure about (N3-?).

However, AgCN is a fancy compound ;) While it is only weakly soluble, Ag(CN)2- complex has high stability constant (log K = 20.48). In effect reaction

2AgCN(s) <-> Ag(CN)2- + CN-

increases AgCN solubility.

That's what I suspect from the very beginning, I am just not sure.
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Offline AhmedEzatAlzawalaty

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Re: precipitimetry
« Reply #7 on: March 09, 2007, 08:23:24 AM »
 i meant to say that why AgCN dissolves AgI,AgBr,AgI but not Ag2S and why silver ammine on the other hand dissolves AgCl efficiently , AgBr slightly and AgI not dissolved at all by it?
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Offline Borek

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Re: precipitimetry
« Reply #8 on: March 09, 2007, 09:03:20 AM »
Quote from: ahmedezat on March 09, 2007, 08:23:24 AM
i meant to say that why AgCN dissolves AgI,AgBr,AgI but not Ag2S and why silver ammine on the other hand dissolves AgCl efficiently , AgBr slightly and AgI not dissolved at all by it?


You are repeating exactly the same statement for the second or third time. This statement is not clear in English. Try to ask the same question using different words, or try to describe th eexperiment that you refer to.
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Offline AhmedEzatAlzawalaty

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Re: precipitimetry
« Reply #9 on: March 14, 2007, 04:33:58 PM »
i mean AgI AgBr AgCl are dissolved efficiently in AgCN but when i tried to dissolve Ag2S in AgCN it didnt dissolve at all.
And Silver ammine dissolves all the AgCl , some of AgBr and none of AgI solids.
here AgCN and Silver ammine are solvents.
i think its clear now.
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Offline AWK

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Re: precipitimetry
« Reply #10 on: March 15, 2007, 03:01:54 PM »
Quote from: ahmedezat on March 14, 2007, 04:33:58 PM
i mean AgI AgBr AgCl are dissolved efficiently in AgCN but when i tried to dissolve Ag2S in AgCN it didnt dissolve at all.
And Silver ammine dissolves all the AgCl , some of AgBr and none of AgI solids.
here AgCN and Silver ammine are solvents.
i think its clear now.
Not in AgCN but in KCN or NaCN
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Offline AhmedEzatAlzawalaty

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Re: precipitimetry
« Reply #11 on: March 15, 2007, 04:48:13 PM »
Ok that s right KCN or NaCN but why ? can u explain me what happened.
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Offline AWK

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Re: precipitimetry
« Reply #12 on: March 19, 2007, 05:57:20 AM »
Because anion CN- forms a strong soluble complex with Ag+
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Offline AhmedEzatAlzawalaty

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Re: precipitimetry
« Reply #13 on: March 19, 2007, 01:04:22 PM »
SO?
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Offline AWK

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Re: precipitimetry
« Reply #14 on: March 20, 2007, 06:00:24 AM »
AgCl(s) + 2CN-(aq) = [Ag(CN)2-](aq) + Cl-(aq)
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