산화-환원 적정 곡선

Oxidation-Reduction Titration Curve Both Half Reactions Homogeneous in Coefficient

균일계수 산화환원 적정에 있어서의 전위의 적정분율에 따른 변화을 나타내는 정확한 방정식을 얻었다. 이 방정식은 정정곡선이 시약의 농도에 무관계함을 알려준다. 또한 전위차적정범위 종말점의 예민도는 반전지의 기준전위의 차는 몰론, 각 반반응에 관여하는 전자수에 따라 심한 영향을 받음을 알려준다. 적정곡선의 변곡점이 당량점과 일치하지 않음을 증명하였다. 또한 적정단계에 따른 반응의 완결도를 평형상수식을 토대로 하여 해석하였다. 이 결과는 산화환원 이외의 평형에도 적용된다.

An exact expression of the titration fraction as a function of the potential is derived for the cases where the coefficients of the both half reactions involved in the titration are homogeneous. It shows that the potential is independent of the concentration of the reagents not only at the equivalence point but also at all titration fractions. The sharpness of the end point detection by potentiometric method is shown to depend not only on the difference of the normal potentials involved but also strongly on the number of electrons transferred in each half reaction. The inflexion point of the potentiometric titration curve is shown to be slightly off from the equivalence point, including the cases where the number of electrons involved are equal. Completeness of the reaction in the course of titration is analyzed, too, mostly in terms of equilibrium constant, thus most of the results are applicable to any type of equilibrium in a single phase with particular relationship of coefficients of chemical equation.