How do you do redox titration problems?

1 Answer
anor277
Jul 11, 2017

Well you require a stoichiometrically balanced equation, which represents the redox transfer....... determination of oxalic acid by potassium permanganate is a good example.

Explanation:

"Permanganate ion," MnO_4^(-) is a commonly used reagent for redox titrations........Why? Well because as Mn(VII+) it is strongly coloured RED; and Mn(II+), its reduction product is almost colourless.....and we must supply the reduction half equation....

Deep purple permanganate ion, Mn(VII+), is reduced to colourless Mn^(2+):

MnO_4^(-)+8H^+ + 5e^(-) rarr Mn^(2+) + 4H_2O (i)

Charge and mass are balanced as required......

Meanwhile oxalic acid is oxidized to carbon dioxide.......C(+III)rarrC(+IV).........

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

We takes 2xx(i)+5xx(ii) to eliminate the electrons.......

2MnO_4^(-)+6H^++5HO(O=)C-C(=O)OH(aq)rarr 2Mn^(2+) + 10CO_2(g)uarr+ 8H_2O(l)

Vizualization of the endpoint is made easy by the disappearance of the colour of permanganate.... The stoichiometry follows the given equation.

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