Question

How do we represent the oxidation of oxalate ion by permanganate ion?

How do we represent the oxidation of oxalate ion by permanganate ion by the half-equation method? What colour change would we observe in the titration?

Answer 1

`"Permanganate ion"` is coloured a bright purple....

Explanation:

And conveniently, it is reduced to `Mn^(2+)`, which is almost colourless. This change is very recognizable, and the stoichiometric endpoint is very accessible.

`"Reduction half equation:"`

`underbrace(MnO_4^(-))_"bright purple" + 8H^(+)+5e^(-) rarr Mn^(2+)+4H_2O(l)` `(i)`

`"Oxidation half equation:"`

`C_2O_4^(2-) rarr 2CO_2(g)+2e^(-)` `(ii)`

And so we take `2xx(i)+5xx(ii)` to give.....

`2MnO_4^(-) +5C_2O_4^(2-)+ 16H^(+)rarr 2Mn^(2+)+10CO_2(g)+8H_2O(l)`