G归东理工大 Analytical chemistry Chapter 6 Oxidation-reduction titration Learning objectives >To master the fundamental principles and relevant calculations about oxidation-reduction equilibrium; >To master the calculation of titration curve,the end point and the titration and the titration break; Toknow about the application of oxidatioction titration. 2025/4/6
Analytical chemistry 2025/4/6 Chapter 6 Oxidation-reduction titration Learning objectives ➢To master the fundamental principles and relevant calculations about oxidation-reduction equilibrium; ➢To master the calculation of titration curve, the end point and the titration and the titration break; ➢To know about the application of oxidation-reduction titration
G山东第王大军 Analytical chemistry The word redox is frequently applied to oxidation- reduction reactions.A redox titration is based on an oxidation-reduction reaction between analyte and titrant. Even though many of the oxidizing agents can be used as titrants,few are primary standards.Most reducing agents react with oxygen and require protection from air to be used as titrant. 2025/4/6
Analytical chemistry 2025/4/6 The word redox is frequently applied to oxidationreduction reactions. A redox titration is based on an oxidation-reduction reaction between analyte and titrant. Even though many of the oxidizing agents can be used as titrants, few are primary standards. Most reducing agents react with oxygen and require protection from air to be used as titrant
归东工大军 Analytical chemistry 6.1 Redox reaction 1.Conditional potentials A redox reaction often can be arranged as a cell,such as: Zn ZnSO(x molL)CuSO(y mol/L)Cu At anode,Zn is oxidized Zn-2eZn2+ At cathode,Cu2+is reduced Cu2++2e→Cu 2025/4/6
Analytical chemistry 2025/4/6 6.1 Redox reaction 1. Conditional potentials A redox reaction often can be arranged as a cell, such as: Zn | ZnSO4 (x mol/L) ||CuSO4 (y mol/L) |Cu 2+ Zn - 2e Zn At anode, Zn is oxidized At cathode, Cu2+ is reduced Cu 2e Cu 2+ +
山东理工大 Analytical chemistry The electromotive force of the cell can be obtained from the difference between the potentials of the two electrodes E=p,-0.=9au2+10w-9an2*a） The potentials of the electrodes is obtained by Nernst equation nFa°red So the potentials of the electrodes is determined by the activities of the oxidized and reduced forms.At the unit activities,it is the standard potential. 2025/4/6
Analytical chemistry 2025/4/6 The electromotive force of the cell can be obtained from the difference between the potentials of the two electrodes (Cu /Cu) (Zn /Zn) - E =+ - = 2+ − 2+ The potentials of the electrodes is obtained by Nernst equation Red 0 OX ln b a a a nF RT = + So the potentials of the electrodes is determined by the activities of the oxidized and reduced forms. At the unit activities, it is the standard potential
归东王大军 Analytical chemistry In practice,however,some factors that affect the potential should be taken into account.For instance,consider the potential of the Fe3+/Fe2+couple in the presence of HCI. D=0'+0059g0 =p°+0.059 YraIF3] Yre2.[Fe2+] In the HCI solution,ferric ion complex with H2O and Cl as follows 2025/4/6
Analytical chemistry 2025/4/6 In practice, however, some factors that affect the potential should be taken into account. For instance, consider the potential of the Fe3+/Fe2+ couple in the presence of HCl. + + = + 2 3 Fe 0 Fe 0.059lg a a [Fe ] [Fe ] 0.059lg 2 Fe 3 0 Fe 2 3 + + + + = + In the HCl solution, ferric ion complex with H2O and Cl- as follows :