0 a substance that is colourless when it is mixed with an acid and pink or red when mixed with an alkali --
1 a substance that is colorless when it is mixed with an acid and pink or red when mixed with an alkali --
A universal indicator is typically composed of water, propan-1-ol, phenolphthalein sodium salt, sodium hydroxide, methyl red, bromothymol blue monosodium salt, and thymol blue monosodium salt.
In several sources, the structure of phenol red is shown with the sulfur atom being part of a cyclic group, similar to the structure of phenolphthalein.
Phenolphthalein's past use for its laxative properties has been discontinued due to concerns it may be carcinogenic.
Developer fluids may be applied using a spray bottle, but some developers are in the form of vaporous, e.g. ammonia fumes used to develop phenolphthalein ink.
Phenolphthalein is used in a test to identify substances that are thought to be, or to contain, blood.
This is typically achieved by boiling an alkaline solution of phenolphthalein with powdered zinc, which reduces the phenolphthalein into phenolphthalin.
The acid-base indication abilities of phenolphthalein also make it useful for testing for signs of carbonation reactions in concrete.
It is closely related to bisacodyl, sodium picosulfate, and phenolphthalein.
