What characteristic of phenolphthalein make it appropriet to use in a titration lab?
Phenolphthalein has a very predictable color change, turning pink at pH 8.2. This is useful for titration because it’s a very easy way to determine the moment the pH changes. Can you do a lab without it? I suppose it depends on the lab. If you want your solution to be a precise pH, you could repeatedly test it with litmus paper, or use an electric pH reader, but the easiest way to do it is with a chemical indicator. Not sure what you mean by “end point” — but if you mean the point at which it changes to pink — the equivalence of an acid/base reaction is directly related to the pH. Knowing that your solution is precisely at pH 8.2 enables you to determine the concentration of Hydronium (H3O) and Hydroxide (OH) ions.
