MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Phenolphthalein at pH9.3. In a base solution phenolphthalein is a pink colour. Adding a dilute acid turns it gradually colourless. At pH 9.3 the colour is barely perceivable and by pH 8 it is colourless.
Model release not required. Property release not required.