WAEC - Chemistry (2011 - No. 27)
The colour of phenolphthalein indicator in alkaline solution at the end-point of an acid-base titration is?
colourless
orange
pink
yellow
解释
Phenolphthalein is one of the most commonly-used indicators in neutralisation titration.
Phenolphthalein is naturally colorless but turns pink in alkaline solutions.