Jacob Keller wrote:
Just to make sure I understand pH correctly: isn't it true that the
[OH-] should always be the same at a given pH (by definition)?
Maybe not by definition but by equilibration with [H+] to make water:
[H][OH]/[H2O] = Kw
[OH] = Kw[H2O]/[H]
if [W] is taken as unity then Kw is ~ 10^-14
[OH] = (~10^-14)/[H]
pOH = ~14 - pH
If neutrality is when [H] = [OH] that would be when pH = pKw/2
which is _approximately_ 7 depending on temperature, ionic strength etc.
(some students get the idea that neutrality is defined to be pH == 7.0000)
JPK
On Fri, May 11, 2012 at 11:48 AM, Katherine Sippel
<katherine.sip...@gmail.com <mailto:katherine.sip...@gmail.com>> wrote:
That is probably because you pH Tris with HCl rather than HEPES with
NaOH. The Ksp for Zn(OH)2 is 3x10^17 so the excess hydroxides are
probably what are killing your solution.
Cheers,
Katherine
On Fri, May 11, 2012 at 11:43 AM, Rajesh Kumar <ccp4...@hotmail.com
<mailto:ccp4...@hotmail.com>> wrote:
If there is no cure , then fine.
pH may not be the answer as it doesn't Happen with TRIS buffer
pH 7.6.
Thanks to every one
Rajesh
------------------------------------------------------------------------
Date: Fri, 11 May 2012 12:35:45 -0400
From: dj...@cornell.edu <mailto:dj...@cornell.edu>
Subject: Re: [ccp4bb] zinc with HEPES
To: CCP4BB@JISCMAIL.AC.UK <mailto:CCP4BB@JISCMAIL.AC.UK>
There is no cure for HEPES.
--
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All Things Serve the Beam
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
schul...@cornell.edu
<mailto:schul...@cornell.edu>
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Jacob Pearson Keller
Northwestern University
Medical Scientist Training Program
email: j-kell...@northwestern.edu <mailto:j-kell...@northwestern.edu>
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