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  2. Phenolphthalein - Wikipedia

    en.wikipedia.org/wiki/Phenolphthalein

    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.

  3. pH indicator - Wikipedia

    en.wikipedia.org/wiki/PH_indicator

    Normally, the indicator causes the color of the solution to change depending on the pH. Indicators can also show change in other physical properties; for example, olfactory indicators show change in their odor. The pH value of a neutral solution is 7.0 at 25°C (standard laboratory conditions). Solutions with a pH value below 7.0 are considered ...

  4. Invisible ink - Wikipedia

    en.wikipedia.org/wiki/Invisible_ink

    In most cases, these substance changes color when mixed with an acid or base. Phenolphthalein, commonly used as a pH indicator, turns pink in the presence of a base such as ammonia fumes or sodium carbonate. Vinegar, is revealed by red cabbage water [12] Vinegar contains acetic acid that affects the pH indicator in red cabbage water. Vinegar ...

  5. Acid–base titration - Wikipedia

    en.wikipedia.org/wiki/Acid–base_titration

    Its sharp and easily detectable colour changes makes phenolphthalein a valuable tool for determining the endpoint of acid-base titrations, as a precise pH change signifies the completion of the reaction. When a weak acid reacts with a weak base, the equivalence point solution will be basic if the base is stronger and acidic if the acid is stronger.

  6. Kastle–Meyer test - Wikipedia

    en.wikipedia.org/wiki/Kastle–Meyer_test

    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.

  7. Alkali - Wikipedia

    en.wikipedia.org/wiki/Alkali

    This means that they will turn phenolphthalein from colorless to pink. Concentrated solutions are caustic (causing chemical burns). Alkaline solutions are slippery or soapy to the touch, due to the saponification of the fatty substances on the surface of the skin.

  8. Concrete degradation - Wikipedia

    en.wikipedia.org/wiki/Concrete_degradation

    Phenolphthalein is a pH indicator, whose color turns from colorless at pH < 8.5 to pink-fuchsia at pH > 9.5. A violet color indicates still alkaline areas and thus non-carbonated concrete. Carbonated zones favorable for steel corrosion and concrete degradation are colorless. [3] [4]

  9. Talk:Phenolphthalein - Wikipedia

    en.wikipedia.org/wiki/Talk:Phenolphthalein

    Phenolphthalein does indeed turn orange in very strong acid solutions (hydronium > 10M). Have a chemistry teacher put some full strength sulfuric acid in a small beaker (do this in a fume hood), and add a few drops of the indicator. It will turn orange. — ★ Parsa ☞ talk 21:53, 1 May 2013 (UTC)