Question

Why does the pink color of titration disappear?

Answer 1

1. Titration is a laboratory method for quantitative chemical analysis used to calculate the concentration of an identified analyte (a substance to be analyzed)
2. The reaction that occurs during an acid-base titration with the help of an indicator is a type of neutralization reaction.
3. The equivalence point, or the ideal point for the completion of the titration, occurs when the moles of a standard solution are equal to the moles of an unknown concentration (analyte).
4. The equivalency point is the ideal point for titration completion. By means of an indication, the end point often illustrates the equivalence point. When the titration hits the endpoint, for instance, with a color indicator, the solution changes color.
5. Due to a higher concentration of the ${\mathrm{H}}^{+}$ ion at the start of the titration, phenolphthalein (a common indicator) in an acidic environment in the flask appears colorless.
6. Acid is neutralized when a base is gradually added. The pink color appears only for a few seconds in the starting indicating that there is still more concentration of ${\mathrm{H}}^{+}$ ions.
7. One more drop of base (${\mathrm{OH}}^{-}$ ions) is all that is needed to turn phenolphthalein pink once all of the acids have been neutralized, indicating that the endpoint has been reached.
8. If the color change of a solution lasts for a few seconds it indicates that it is reaching its endpoints and if the color change of the solution is permanent it means it has reached its endpoint now and the reaction is complete.

Therefore, the pink color of titration disappears as an indication that the reaction is reaching its endpoint.