phenolphthalein: A dye used as anacid-base indicator. It is colourlessbelow pH 8 and red above pH 9.6. Itis used in titrations involving weakacids and strong bases. It is also usedas a laxative. brand name Evac-Q-Tabs (Savage); Ex-Lax (Novartis); Modane (Savage); Prulet (Mission ...
When phenolphthalein is used as the indicator in a titration of an HCl solution with a solution ofNaOH, the indicator undergoes a colour change from colourless to poink at the end point of the tiration. This colour change occurs abruptly because ...
Phenolphthalein is colourless and clear in acidic solutions, but imparts an intense puce pink colour in alkaline solutions of higher pH, with λ(max) = 552 nm. The coloured form of phenolphthalein contains a quinone moiety; in fact, any chromophore based on a quinone has a red colour...