Rücktitration

Rücktitration, also known as back titration, is a laboratory technique used in analytical chemistry. It is employed when a direct titration is difficult or impossible to perform accurately. This often occurs when the analyte reacts very slowly, is volatile, or when the titrant is not readily available or stable.

In a Rücktitration, a known excess amount of a reagent (the back-titrant) is first added to the solution containing the analyte. This back-titrant is chosen because it reacts quickly and quantitatively with the analyte, or with a substance that is produced from the analyte's reaction. After allowing sufficient time for the reaction between the analyte and the back-titrant to complete, the unreacted excess of the back-titrant is then titrated with a standard solution of another reagent.

The amount of the analyte is indirectly determined by calculating the amount of the back-titrant that reacted with it. This is done by subtracting the amount of back-titrant that was titrated from the initial total amount of back-titrant added. The difference represents the amount of back-titrant that reacted with the analyte. This method can improve accuracy by allowing the use of more stable or easily handled titrants for the final step.