acid-base indicators
acid-base indicators:
see indicators, acid-baseindicators, 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 p
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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 litmuslitmus,organic dye usually used in the laboratory as an indicator of acidity or alkalinity (see acids and bases). Naturally pink in color, it turns blue in alkali solutions and red in acids. Commonly, paper is treated with the coloring matter to form so-called litmus paper.
..... Click the link for more information. . Most indicators are also used in large amounts for dyeing; small quantities are nonetheless invaluable for use as indicators in chemical laboratories.