Equivalence point

Different methods to determine the equivalence point include: pH indicator : A pH indicator is a substance that changes color in response to a chemical change. An acid-base indicator, such as 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 approximation of the equivalence point. Amperometry : Amperometry can be used as a detection technique (amperometric titration). The current due to the oxidation or reduction of either the reactants or products at a working electrode will depend on the concentration of that species in solution. The equivalence point can then be detected as a change in the current. This method is most useful when the excess titrant can be reduced, as in the titration of halides with Ag+. (This is also useful because it ignores precipitates.) ==See also==