Abstract: Endpoint error is an important topic in analytical chemistry education. Based on the theory of precipitation-dissolution equilibrium and the definition of endpoint error, a general formula for calculating the endpoint error in the Mohr method has been derived. The application of this formula in directly calculating the endpoint error, determining the titration jump range, and determining the minimum required amount of indicator is introduced, and the calculated results are consistent with the literature values. The construction of this formula further improves the new methodological system for calculating endpoint errors, which will effectively promote the development of first-class courses in analytical chemistry.

Key words: Precipitation titration, Endpoint error, Titration jump, Indicator