Question

How many coulombs are require for the following reductions?
(i) $1mole$ of $A{g}^{+}$ ions to $Ag$
(ii) $1mole$ of $C{u}^{2+}$ ions to $Cu$
(iii) $1mole$ of $Mn{O}_4^{-}$ ions to $Mn{O}_4^{2-}$.

Answer 1

$A{g}^{+}$ + $e^{-}$ $\to$ Ag

for 1 mole it require 1 F

$C{u}^{+}$ + 2$e^{-}$ $\to$ Cu

for 1 mole it require 2 F

Mn$O_4$${}^{-}$ + $e^{-}$ $\to$ $Mn{O}_4$${}^2-$

for 1 mole it require 1 F

total F require = 4

and 1F = 96485.3 coulombs

so, total coulombs require = 4*96485.3 = 385941.2 coulombs.