I just purchased a PH meter. I got a Hanna Piccolo 2. No more guessing
games for me.




"Joe Sallustio" > wrote in message
om...
> Stop at the permanent color change.
>
> Can someone please give me insight regarding the end
> > >> point color I should be watching for? A red will gradually turn to a
> > >> reddish-gray,
>
> The Europeans use 7 as the endpoint, North Americans use 8.2. I have
> noted it's not that big a difference just as Greg mentioned, the PH
> really takes off around 7. I use 8.2
>
>
> > > using a ph meter to check for the end point takes all the guess work
> > > out of the end point. many on the board have said that the endpoint is
> > > when you measure a ph of 8.2, however, my bottle of blueing solution
> > > says to measure to 7.0 so that's what i do.
> >
>
> ...> Using a pH meter to titrate would be a
> > preferred method with reds. Generally we titrate to pH 8.2 because that
is
> > the pH at which phenolphthalein changes color. Thus, it would be
consistent
> > with colorimetric titrations. I think the difference between pH 7 and
8.2
> > during the titration is a matter of just a few drops anyway (the
titration
> > curve is very very steep at the point of neutralization of the acids).