Re: Tanning theory of dichromated colloids (was gelatin

From: MARTINM <martinm@SoftHome.net>
Subject: Re: Tanning theory of dichromated colloids (was gelatin
Date: Tue, 18 May 2004 19:35:25 +0200

> Could it be the relatively high pH (EDTA being fairly basic)? Cr(III) is
> said to require an acidic environment.

Unlikely. Experiments like those must control for the pH or the result
doesn't mean anything. EDTA 4- can simply come in different forms of salts.

In theory EDTA's complexing effect is stronger at higher pH but acidic
condition is actually preferred for many chelating reactions because
in base, OH- competes to make M(OH)n form, which is often insoluble.

--
Ryuji Suzuki
"You have to realize that junk is not the problem in and of itself.
Junk is the symptom, not the problem."
(Bob Dylan 1971; source: No Direction Home by Robert Shelton)