A Accuracy investigation of second derivative method to determine an end point of weak acid-Bases potentiometric titration

used second derivative method to determine an end point of potentiometric titration,the effects of titration accuracy to strong acid bases and weak ones were theoretically analyzed.In some condition,it was found that there is better used second derivative method to determine an end point of only K a≤1.13×10 -7 .When K a or K b is bigger till strong acid bases,it doesn't improve accuracy.Otherwise,near a theminate point,titration volume is small and equality,it also improves accuracy.