hapettavaindikaattoreita

Hapettavaindikaattoreita, or oxidation-reduction indicators, are chemical compounds that undergo a distinct color change when they are oxidized or reduced. This color change is reversible, meaning the indicator will return to its original color when the redox potential of the solution changes back. These indicators are crucial in analytical chemistry for determining the endpoint of a redox titration.

The principle behind their function lies in the indicator molecule itself acting as a redox system. When the potential of the solution reaches a certain level, the indicator will either be oxidized or reduced, causing a structural rearrangement that alters its light absorption properties and thus its observed color. The specific potential at which this color change occurs is known as the redox potential of the indicator.

Common examples of hapettavaindikaattoreita include ferroin, which changes from red to pale blue, and methylene blue, which goes from blue to colorless. The choice of indicator depends on the redox potential difference between the titrant and the analyte and the desired precision of the titration. They are added in small quantities to the solution being titrated, and the appearance of a persistent color change signals that the reaction is complete.