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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.
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.
A roll of universal indicator pape 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 solution ...
Indicator: A substance that changes color in response to a chemical change. An acid–base indicator (e.g., phenolphthalein) changes color depending on the pH. Redox indicators are also used. A drop of indicator solution is added to the titration at the beginning; the endpoint has been reached when the color changes.
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 ...
Color change In some reactions, the solution changes color without any added indicator. This is often seen in redox titrations, for instance, when the different oxidation states of the product and reactant produce different colors. Precipitation If the reaction forms a solid, then a precipitate will form during the
The equipment required is a colorimeter, some cuvettes and a suitable color reagent. The process may be automated, e.g. by the use of an AutoAnalyzer or by flow injection analysis . Recently, colorimetric analyses developed for colorimeters have been adapted for use with plate readers to speed up analysis and reduce the waste stream.
In chemistry, solvatochromism is the phenomenon observed when the colour of a solution is different when the solute is dissolved in different solvents. [1] [2] Reichardt's dye dissolved in different solvents. The solvatochromic effect is the way the spectrum of a substance (the solute) varies when the substance is dissolved in a variety of ...