α-Naphtholphthalein (C
28H
18O
4) is a
phthalein dye used as a
pH indicator
A pH indicator is a halochromic chemical compound added in small amounts to a solution so the pH (acidity or basicity) of the solution can be determined visually or spectroscopically by changes in absorption and/or emission properties. Hen ...
with a visual transition from colorless/reddish to
greenish blue at pH 7.3–8.7.
References
PH indicators
1-Naphthols
Phthalides
Triarylmethane dyes
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