Quick Answer: The High Purity Phenolphthalein Indicator Solution is a prepared acid-base indicator that stays colourless in acidic and near-neutral solutions and turns pink as the solution becomes alkaline, marking endpoints in suitable titrations.
Last updated: October 2026
Key Features
Indicator compound phenolphthalein, formula C20H14O4
Colourless-to-pink change in its alkaline transition range
Commonly cited transition range of about pH 8.2 to 9.8
Ready-prepared liquid for controlled dropwise addition
Used for alkali detection and for comparing indicator ranges
Technical Specifications
Specification
Value
Indicator compound
Phenolphthalein
Chemical formula
C20H14O4
Colour transition
Colourless to pink
Transition range
Approximately pH 8.2 to 9.8
About This Product
Only the number of drops given in the method is added to the test solution, and the flask is swirled continuously as the endpoint approaches. The first persistent pale-pink colour marks the endpoint where the method requires it. Keeping the quantity small avoids excess indicator distorting the result.
Frequently Asked Questions
Q1. Why is phenolphthalein supplied as a solution? A prepared solution can be added drop by drop straight away, without first dissolving the solid indicator, which helps control the amount used.
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