BCPneumatics - 13-4-2007 at 17:32
Hey guys, me again with a rather 'noobish' question.
A friend of mine has given me a couple grams of phenolphthalein, and I wanted to know if there is any reason it could not be made into a solution with
70% isopropanol, to be used as an indicator in neutralization titrations. The only references I can find to any solution using under 90% isopropanol
is used to test the pH of soap, but it seems to test in the same range. (8.4-10.0) All chemistry references I see are to 1% in 90/91% isopropanol.
Thanks for the help,
Brian.
Ozone - 13-4-2007 at 18:50
It will probably work fine (a little phenolphthalein goes a long way). I use 1% in EtOH; 1 drop (tops) per titration works like a charm).
Remember, 1%=10,000ppm.
Cheers,
O3
pantone159 - 14-4-2007 at 07:17
I would think it would work, I have seen phenolphthalein indicator specified as a 1% in 50/50 EtOH/H2O solution, so 70% alcohol ought to work.
BCPneumatics - 14-4-2007 at 11:03
Okay. There is always a part of my mind that says I am overlooking something, but as far as I can tell, there is not a whole lot of reason to use
over 70% for what I am doing.
Any more input?
Ozone - 14-4-2007 at 13:06
As long as it dissolves, your cool. Use a concentrated solution so that the amount added does not cause volumetric error in your titration. Unless you
are titrating in an organic solvent (which your not b/c you are using phenophthalein), it makes little difference.
Just go for it,
O3