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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.
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 ...
Paper form: It is a strip of coloured paper which changes colour to red if the solution is acidic and to blue, if the solution is basic. The strip can be placed directly onto a surface of a wet substance or a few drops of the solution can be dropped onto the universal indicator using dropping equipment.
A pH indicator is 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 frequently used. A drop of indicator solution is added to the titration at the start; when the color changes the endpoint has been reached, this is an ...
Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a color reagent.It is applicable to both organic compounds and inorganic compounds and may be used with or without an enzymatic stage.
The meter reading (in millivolts) is plotted against the volume of titrant. The end point is taken at the distinct inflection of the resulting titration curve corresponding to the basic buffer solution. Color indicating titration: An appropriate pH color indicator e.g. phenolphthalein, is used. Titrant is added to the sample by means of a burette.
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.
Neutral litmus paper is purple. [2] Wet litmus paper can also be used to test for water-soluble gases that affect acidity or basicity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, turns red litmus paper blue. While all litmus paper acts as pH paper, the opposite ...