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  2. Phenolphthalein - Wikipedia

    en.wikipedia.org/wiki/Phenolphthalein

    Phenolphthalein (/ f ɛ ˈ n ɒ l (f) θ ə l iː n / [citation needed] feh-NOL(F)-thə-leen) is a chemical compound with the formula C 20 H 14 O 4 and is often written as "HIn", "HPh", "phph" or simply "Ph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations.

  3. List of reagent testing color charts - Wikipedia

    en.wikipedia.org/wiki/List_of_reagent_testing...

    It is advised to check the references for photos of reaction results. [1] Reagent testers might show the colour of the desired substance while not showing a different colour for a more dangerous additive. [2]

  4. Acid–base titration - Wikipedia

    en.wikipedia.org/wiki/Acid–base_titration

    Three different points in an acid-base titration using phenolphthalein as the indicator. Phenolphthalein is widely recognized as one of the most commonly used acid-base indicators in chemistry. [12] Its popularity is because of its effectiveness in a broad pH range and its distinct colour transitions. [12]

  5. Phthalein dye - Wikipedia

    en.wikipedia.org/wiki/Phthalein_dye

    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 ...

  6. Universal indicator - Wikipedia

    en.wikipedia.org/wiki/Universal_indicator

    A roll of universal indicator paper Colors of universal indicator. A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a ...

  7. Chromophore - Wikipedia

    en.wikipedia.org/wiki/Chromophore

    The color that is seen by our eyes is that of the light not absorbed by the reflecting object within a certain wavelength spectrum of visible light. The chromophore indicates a region in the molecule where the energy difference between two separate molecular orbitals falls within the range of the visible spectrum (or in informal contexts, the ...

  8. Complexometric indicator - Wikipedia

    en.wikipedia.org/wiki/Complexometric_indicator

    A complexometric indicator is an ionochromic dye that undergoes a definite color change in presence of specific metal ions. [1] It forms a weak complex with the ions present in the solution, which has a significantly different color from the form existing outside the complex. Complexometric indicators are also known as pM indicators. [2]

  9. Kastle–Meyer test - Wikipedia

    en.wikipedia.org/wiki/Kastle–Meyer_test

    The Kastle–Meyer test is a presumptive blood test, first described in 1903, in which the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin. It relies on the peroxidase -like activity of hemoglobin in blood to catalyze the oxidation of phenolphthalin (the colorless reduced form of phenolphthalein) into ...