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The discovery of phenolphthalein's laxative effect was due to an attempt by the Hungarian government to label [clarification needed] genuine local white wine with the substance in 1900. Phenolphthalein did not change the taste of the wine and would change color when a base is added, making it a good label in principle.
Upon reduction, the very intense pink color of the cationic form of phenolphthalein fades to a faint yellow color. It is this form of phenolphthalein that is present in Kastle–Meyer test kits. In order to generate the intense pink color indicative of a positive test, the reduced phenolphthalein must be oxidized back to its normal, colored form.
Chemical structure of phenolphthalein, a common phthalein dye. Phthalein dyes are a class of dyes mainly used as pH indicators, due to their ability to change colors depending on pH. [1] They are formed by the reaction of phthalic anhydride with various phenols. They are a subclass of triarylmethane dyes. Common phthalein dyes include ...
Phenolphthalein; References This page was last edited on 17 February 2025, at 20:47 (UTC). Text is available under the Creative Commons Attribution-ShareAlike 4.0 ...
Manganese dioxide: blackish or brown in color, used since prehistoric times (MnO 2). Titanium pigments. Titanium black: Titanium(III) oxide (Ti 2 O 3). White pigments
Crayola is making colorful history! For the first time in the company’s more than 120-year history, the brand is bringing back eight previously retired colors. Dandelion, Blizzard Blue, Magic ...
For optimal accuracy, the color difference between the two species should be as clear as possible, and the narrower the pH range of the color change the better. In some indicators, such as phenolphthalein, one of the species is colorless, whereas in other indicators, such as methyl red, both species confer a color. While pH indicators work ...
2. Baking and Bonding. During the pandemic, baking became a cultural obsession. Those who had hardly set foot in a kitchen suddenly began cultivating their own sourdough starters—and for good ...