PHENOLPHTHALEIN, 1% W/V

Phenolphthalein 1% w/v is an organic pH indicator and is widely used as an acid-base titration and routine analytical procedure. It gives a visible color change which can be used to identify the end point of reactions that involve acidic and alkaline solutions.
In acidic conditions the indicator will be colorless, in basic conditions it will be pink. The indicator is sensitive in the range of approximately pH 8.2 to 10.0. The change is distinctive, and so the technique is useful for detecting changes in alkalinity during a titration.
Phenolphthalein is a member of the phthalein dye group and is slightly soluble in water. It is commonly prepared in a suitable solvent to produce an indicator solution for laboratory use. The product is supplied as a clear, colourless solution and passes the specified sensitivity test. Its colour transition can provide a convenient visual indication of the endpoint when the titration conditions are appropriate.
As an indicator, phenolphthalein does not provide an exact pH measurement. The effectiveness depends on the pH range of the reaction and on the state of the sample. Observed color change can be affected by contamination or inappropriate reaction conditions.

Used as a pH indicator in acid-base titrations, showing a colour change from colourless to pink in alkaline conditions.