100. Solving a chemistry problem

3.1. For redox element type Pt | A, B | | C, D | Pt according to the standard electrode potentials of half-cells (Handbook of physico-chemical quantities), write an equation and calculate the equilibrium constants of the oxidation-reduction reaction. Calculate the EMF of the element at 298 K. Consider that αH2O=1, αH=0.2
Variant No. A B C D aA aB aC aD
3* MnO4- Mn2 MnO2 Mn2 0.009 0.014 0.001 0.07
*- H and H2O are involved in the reaction