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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: ash2006rf on November 21, 2009, 04:53:17 PM

Title: indicator for pb
Post by: ash2006rf on November 21, 2009, 04:53:17 PM
Hi i work on titration of pb using Xylenol Orange tetrasodium salt
indicator for metal titration.
if any one he have idea about other indicator may i can use it instead . because its difficult for me to find this one.
thank you in advance
for further information will be ready.
Ash
Title: Re: indicator for pb
Post by: BetaAmyloid on November 21, 2009, 06:49:52 PM
So...are you asking if there is something to be sure that there is lead in a solution? If so, you could use something like hydrochloric acid and a white precipitate would form that is PbCl2 or PbCl4. This would indicate the presence of lead, but I can't totally understand your question.

2HCl + Pb :rarrow: PbCl2 + H2 (for Pb2+)
4HCl + Pb :rarrow: PbCl4 + 2H2 (for Pb4+)

Hope this is what you were asking. :-\
Title: Re: indicator for pb
Post by: csrscience.com on November 21, 2009, 09:49:57 PM
Lead chloride is slightly soluble, and I think he is probably working on very dilute solutions so this probably wont work.
Title: Re: indicator for pb
Post by: BetaAmyloid on November 22, 2009, 12:51:41 AM
Quote from: IndieSci on November 21, 2009, 09:49:57 PM
Lead chloride is slightly soluble, and I think he is probably working on very dilute solutions so this probably wont work.

Yeah, that's what I'm not understanding. If it is high concentration of lead the precipitate will be obvious...if not, it won't be near as obvious or able to be seen at all.  :-\
Title: Re: indicator for pb
Post by: Borek on November 22, 2009, 04:59:51 AM
This is for titration, so reaction has to be quickly reversible and easy to observe.  Precipitation of chlorides won't work.