Endfarbe

Endfarbe, in chemistry, refers to the color of the solution at the endpoint of a titration—the point at which the added titrant has reacted stoichiometrically with the analyte, as indicated by a color change of the indicator. The observed Endfarbe provides a practical signal to stop the titration, especially in teaching and routine laboratory work. However, the Endfarbe can depend on the indicator used and the composition of the solution, and it may not coincide exactly with the theoretical endpoint, which can introduce systematic error if relied upon without consideration.

Indicator choice hinges on the pH range of the equivalence point and the clarity of the color transition in the given medium. Common indicators include phenolphthalein (end colour typically pink in basic solutions), methyl orange (end colour shifting toward red to orange in acidic conditions, then yellow in basic solutions), and bromothymol blue (yellow to blue around pH 6–7). In redox titrations, the end colour may be the result of the indicator’s own color change or the appearance of a distinct color in the reacting mixture.

Limitations of relying on Endfarbe include subjectivity in color perception, interference from strongly colored samples, and temperature effects on colour change. To improve precision, instrumental methods such as potentiometry (monitoring potential) or spectrophotometry (monitoring absorbance) are often employed to determine the endpoint more accurately. Endfarbe thus represents a practical, observable signal in titration chemistry, complementary to instrumental endpoints.