acid-base indicators

indicators, acid-base

indicators, acid-base, organic compounds that, in aqueous solution, exhibit color changes indicative of the acidity or basicity of the solution. Common indicators include p-nitrophenol, which is colorless from pH 1 to 5 and yellow from pH 5 to 9; methyl orange, yellow in basic and neutral solutions and reddish below pH 3.7; phenolphthalein, colorless in acid and neutral solutions, pink at about pH 8.5, and purplish at pH 10; and litmus. Most indicators are also used in large amounts for dyeing; small quantities are nonetheless invaluable for use as indicators in chemical laboratories.
The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.
References in periodicals archive ?
Another kind of water solution is indicator solution, also known as acid-base indicators. These are actually solutions of weak acid or weak base and are used to determine whether a solution is alkaline or acid.
It is known that acid-base indicators exist in equilibrium between two tautomeric forms and the ratio of the two forms depend on the concentration of hydrogen ions in the medium.
Usefulness of some plant flowers as natural acid-base indicators. J of the Chinese Chemical Society 2002; 49: 63-68.

Full browser ?