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?

1 Answer
anor277
Sep 11, 2017

#"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)#

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